Formulation, Evaluation And Characterization Of Floating
Transcript Of Formulation, Evaluation And Characterization Of Floating
ejpmr, 2019,6(11), 506-518
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Matta et al.
EUROPEAN
JOURNAL
OEFurPopHeaAnRJoMurAnCalEofUPThIaCrmAaLceutical
and
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Research
Research
Article
AND MEDICAL RESEARCH
ISSN 2394-3211
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FORMULATION, EVALUATION AND CHARACTERIZATION OF FLOATING TABLET OF AZITHROMYCIN FOR HELICOBACTOR PYLORI
Neha Arora1, Yogesh Matta1, Dr. Sonu Sharma1, Saurabh Sharma1, Sandeep Singh1, Md Dabeer Ahmad2 1School of Pharmaceutical Sciences, Jaipur National University, Jagatpura, Jaipur.
2Department of Pharmaceutical Sciences, College of Pharmacy, Aldowadmi, Shaqra University KSA.
*Corresponding Author: Mr. Yogesh Matta Assistant Professor, School of Pharmaceutical Sciences, Jaipur National University, Jagatpura, Jaipur.
Article Received on 23/09/2019
Article Revised on 13/10/2019
Article Accepted on 02/11/2019
ABSTRACTS Oral route has been the most popular and successful route used for controlled delivery of drugs. Controlled release of drug delivery system (CRDDS) optimizes the biopharmaceutical, pharmacokinetic, pharmacodynamic, properties of drugs and to reduce the side effects and to designed to deliver the drug in such a way that the levels are maintained within the therapeutic window effective for a long period till the system continuous to deliver the drug at a particular rate. In present study, an attempt was made to formulate floating tablet of Azithromycin in order to enhance bioavailability, reduce dose thereby improve patient compliance. Preformulation studies were done to characterize the chemical and physical properties of drug. FT-IR spectrum and melting point determination confirmed identity and purity of Azithromycin. Azithromycin was subjected to compatibility studies with different excipients, there was no physical change observed in drug and excipients. Further, it was confirmed by taking FTIR graphs.
KEYWORDS: Azithromycin, Excipients, Pharmacokinetic, Pharmacodynamic, Bioavailability.
INTRODUCTION Oral Drug Delivery Systems Oral route has been the most popular and successfully used for controlled delivery of drugs because of convenience and ease of administration. The controlled release systems for oral use are mostly solids and based on dissolution, diffusion or a combination of both mechanisms in controlling the release rate of drug. During the past two decades, numerous oral delivery systems have been developed to act as drug reservoirs from which the active substance can be released over a
defined period of time at a predetermined and controlled rate. Drugs that are easily absorbed from the gastrointestinal tract and have a short half-life are eliminated quickly from the blood circulation. To reduce this problem, the oral controlled release (CR) formulations have been developed, as these will release the drug slowly into the GIT and maintain a constant drug concentration in the serum for a longer period of time. This minimizes several potential problems like saw-tooth kinetics characterized by large peaks and troughs in the drug concentration time curve.
A
B
Fig. 1: Plasma level profiles followings (A) Conventional and (B) Controlled release dosing.
Gastroretentive Drug Delivery Systems It has been suggested that formulating the drugs with narrow absorption window in a unique pharmaceutical
dosage form with gastroretentive properties, would enable an extended absorption phase of these drugs. After oral administration, such a dosage form would be retained in the
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stomach and release the drug there in a extended manner, so that drug could be supplied continuously to its absorption sites in the upper gastrointestinal tract. Gastroretentive dosage form releases medications in a controlled manner which extends the absorption phase of drugs characterized by a limited and narrow absorption window at upper part of gastrointestinal tract or drugs intended to treat local ailments in gastroduodenum. The need for gastroretentive dosage forms has led to extensive efforts in both academia and industry towards the development of such drug delivery systems.
Gastroretentive technologies Various techniques have been pursued to increase the GRT of dosage forms by employing a variety of concepts such as floating, swelling, inflation and adhesion. These systems have been classified according to the basic principles of gastric retention. Floating drug delivery system (FDDS), with low
density providing sufficient buoyancy to float over the gastric contents. High density, which retain the dosage form in the body of stomach for longer period of time, by sedimenting to the folds of stomach. Bioadhesion to gastric mucosa, enabling the localized retention of the system in the stomach. Expansion by swelling or unfolding to a large size which limits emptying of the dosage form through pyloric sphincter.
Helicobacter pylori A peptic ulcer is a sore on the lining of the stomach or duodenum, the beginning of the small intestine. Less commonly, a peptic ulcer may develop just above the stomach in the oseophagus, the tube that connects the mouth to the stomach. A peptic ulcer in the stomach is called a gastric ulcer. One that occurs in the duodenum is called a duodenal ulcer.
People can have both gastric and duodenal ulcers at the same time. They also can develop peptic ulcers more than once in their lifetime. Peptic ulcers are common. Each year in the United States, about half a million people develop a peptic ulcer.
Causative agents for peptic ulcers A bacterium called Helicobacter pylori (H.pylori) is a major cause of peptic ulcers. Nonsteroidal antiinflammatory drugs (NSAIDs), such as asprin and ibuprofen, are another common cause.
Rarely, cancerous or noncancerous tumors in the stomach, duodenum, or pancreas cause ulcers. Peptic ulcers are not caused by stress or eating food, but both can make ulcer symptoms worse. Smoking and drinking alcohol also can worsen ulcers and prevent healing.
Life Cycle of H.Pylori H.pylori is a gram negative spiral shaped bacteria. In humans, it colonises the stomach and the likelihood of
infection increases with age. In the U.K, half of those over 50 are infected. There is some evidence that H.pylori may be associated with gastric cancer. There is no convincing evidence, at present, for a relation between H.pylori and non ulcer dyspepsia.
H.pylori infection by itself is not sufficient to cause peptic ulcers, other factors are needed. These may include hypersecretion of acid, smoking and genetic predisposition.
Helicobacter pylori is an important cause of peptic ulcer disease and chronic gastrititis and has been linked to the pathogensis of gastric malignancy. The bacterium causes peptic ulcers by damaging the mucous coating that protects the stomach and duodenum. Damage to the mucous coating allows powerful stomach acid to get through to the sensitive lining beneath. Together, the stomach acid and H.pylori irritate the lining of the stomach or duodenum and causes ulcer. For these reasons, anti-H.pylori regimens are being investigated with increasing frequency, with about 1500 reports being published between 1984 and 1999. Many combinations of antibiotics and antisecretory drugs have been tested in an attempt to find the optimal regimen. The regimen of choice should be cheap, simple, of short duration, associated with few side-effects, and with an efficacy of 90% or greater. The most popular strategies for producing a high rate (80-95%) of H.pylori eradication entail the use of two antibiotics given for atleast 1week. The use of antibiotics for shorter periods has been investigated infrequently, as a increased daily dose considered necessary is thought to be associated with an increase in side-effects.
Azithromycin is a potentially attractive therapeutic agent for H.pylori, given its excellent mean inhibitory concentration for this organism and long biological half life.
MATERIALS METHODS
Drug Profile
Common name: Azithromycin
Chemical
name:
(2R,3R,4R,5R,8R,10,11R,12S,13S,14R,)-11-
{[(2S.3R,4S,6R)-4-(dimethylamino)-
3hydroxy-6-
methyloxan-2-yl]oxy} -2-ethyl-3,4,10-trihydroxy-13-
{[(2R,4R,5S,6S)-5-hydroxy-
4-methoxy-4,6-
dimethyloxan-2-yl]oxy}-3,5,6,8,10,12,14-heptamethyl-1-
oxa-6azacyclopentadecan-15one.
Molecular formula: C38H72N2O12
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Structural formula
Molecular Weight: 748 Description: It is white or almost white crystalline powder. Solubility: Practically insoluble in water, freely soluble in ethanol and in methylene chloride. Therapeutic category: Antibiotic Melting point: 113-115°C Odour: Odourless
Mechanism
of
action:
Azithromycin
prevents bacteria from growing by interfering with
their protein synthesis It binds to the 50S subunit of the
bacterial ribosome,
and
thus
inhibits translation of mRNA. Nucleic acid synthesis is
not affected.
Uses: Azithromycin is used to treat many different infections, including acute otitis media, nonstreptococcal bacterial pharyngitis, gastrointestinal infections such as traveler's diarrhea, respiratory tract infections such as pneumonia, cellulitis.
Pharmacokinetics: Azithromycin is acid-stable, so it can be taken orally with no need of protection from gastric acids. It is readily absorbed, but its absorption is greater on an empty stomach. Time to peak concentration in adults is 2.1 to 3.2 hours for oral dosage forms and one to two hours after a dose. Due to its high concentration in phagocytes, azithromycin is actively transported to the site of infection. During active phagocytosis, large concentrations are released. The concentration of azithromycin in the tissues can be over 50 times higher than in plasma, due to ion trapping and its high lipid solubility(volume of distribution is too high).
Metabolism: According to Davis Drug Guide for Nurses, following a single 500 mg dose, the half-life of azithromycin is 11–14 h. The longer half-life of 68 h is achieved only when multiple doses are consumed. Biliary excretion of azithromycin, predominantly unchanged, is a major route of elimination. Over the course of a week, approximately 6% of the administered dose appears as unchanged drug in urine.
Side effects: Most common side effects are gastrointestinal: diarrhea (5%), nausea (3%), abdominal pain (3%), and vomiting. Fewer than 1% of patients stop taking the drug due to side effects. Nervousness, dermatologic reactions, and anaphylaxis have been
reported. As with all antimicrobial agents, pseudomembranous colitis can occur during and up to several weeks after azithromycin therapy.
METHODOLOGY Characterization of drug The procured sample of azithromycin was characterized in terms of its physical description, organoleptic properties, melting point and solubility in various solvents.
Establishment of calibration plot To conduct the drug dissolution studies, standard plots for pure drug were constructed by using method described by Preeti Gandhi et al. The absorbance of prepared solutions of azithromycin in 0.1N HCl was measured at 254nm in Shimadzu UV-1700 spectrophotometer against an appropriate blank (0.1N HCl).
Preliminary studies During preliminary studies various polymers viz. HPMC K4M, HPMC K100 and, Carbopol 934, were tried for formulating oral sustained release floating tablets of azithromycin. Tablets were prepared using each of these polymers and using various polymers in different ratio to formulate floating azithromycin tablets.
Preparation of granules Azithromycin was mixed with various grades of HPMC in varying ratio. These batches are mostly prepared by wet granulation method.
Evaluation of granules Angle of repose Flow properties of the granules are evaluated by determining the angle of repose. It is the maximum angle that can be obtained between the free standing surface of the powder heap and the horizontal plane. It is a qualitative assessment of the internal cohesive and frictional effects under low levels of external loading as might apply in powder mixing, on in tablet die or capsule shell filling operation. Tan θ = h/r
Bulk density The ratio of mass to volume is known as density of material. The bulk density is determined by pouring the weighed sample in to a graduated cylinder via a large funnel and measuring its volume.
Tapped density is determined by placing a graduated cylinder containing a non mass of formulation on a mechanical tapper apparatus which is operated at a fix no. of taps until the powder volume has reached a minimum. LBD and TBD were calculated using the following formula. LBD = weight of the powder / volume of the packing TBD = weight of the powder / tapped volume of the packing
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Compressibility index Compressibility index is a simple indication of the ease with a material can be induced to flow. The compressibility index and Hausner index are the measure of porosity of a powder to be compressed. They measure the relative importance of interparticulate interaction. For poorer flowing materials, there are frequently greater interparticulate interactions and greater difference between the bulk and tapped densities. These differences are reflected in the compressibility index and Hausner index.
Compressibility index of the powder was determined by Carr’s compressibility index as given by following eqn. Carr’s index (%) = [(TBD – LBD) x 100]/TBD
Hausner ratio Hausner ratio of the powder was determined by Hausner index as given by the following equation: Hausner index = TBD/LBD
Compression of granules The dried granules were first mixed with magnesium stearate and talc. The granules were then compressed into tablets of average weight 700 mg containing 250mg of azithromycin On a 16 station rotary tablet machine in biconvex shape.
Evaluation of floating tablets The prepared tablets were evaluated for quality control tests like hardness, thickness, friability and drug content uniformity, weight variation, thickness, in vitro dissolution studies and analysis of dissolution data, in vitro buoyancy test and swelling index determination.
Tablet hardness The mechanical strength of tablets is an important property. It has been described by various terms including fracture resistance, hardness, bending strength and crushing strength. Tablet hardness has been defined as the force required breaking a tablet in a diametric compression test.
Friability Friability test was done by Roche friabilator. Six tablets were weighed and were subjected to combined effect of attrition and shock by utilizing a plastic chamber that resolve at 25 rpm dropping the tablets at distance of 6 inch with each revolution. Operated for 100 revolutions, the tablets were dusted and reweighed. The percentage friability was calculated. The average hardness and standard deviation was determined. Percent friability = [(Weightfinal–Weightoriginal) / Weightoriginal] x 100
Uniformity of weight Twenty tablets from each batch were individually weighed and their average weight was calculated. From the average weight of the prepared tablets, the standard deviation was determined.
Drug content uniformity To evaluate a tablet’s potential for efficacy; the amount of drug per tablet needs to be monitored from tablet to tablet and batch to batch.
Thickness The dimensions of the tablet like thickness, length were measured using vernier-calipers. Ten tablets from each batch were selected randomly for this test and the average value was reported.
In vitro buoyancy test The in vitro buoyancy was determined by floating lag time, per the method described by Rosa et al. The tablets were placed in a 100 mL beaker containing as 0.1 N HCl. The time required for the tablet to rise to the surface and float was determined as Floating Lag Time (FLT) and the time period up to which the tablet remained buoyant is determined as Total Floating Time (TFT).
Swelling index determination The swelling behavior of dosage unit can be measured either by studying its dimensional changes, weight gain, or water uptake. Water uptake study of the dosage form is conducted by using dissolution apparatus-II in 900 mL of distilled water which is maintained at 37±0.5°C, rotated at 50 rpm. At selected regular intervals, the tablet is withdrawn and weighed. Swelling of the tablet is expressed as Swelling index (SI). The swelling index of optimized formulation was calculated using the formula shown in equation. SI= (W2 -W1) / W1
Fourier transform infra-red (FTIR) studies The FTIR spectra of the drug and its physical mixtures with polymer blend of selected best formulation were recorded in KBR using an FTIR spectrophotometer.
RESULTS AND DISCUSSION Preformulation Studies Characterization of drug A). Physical Description Azithromycin was found to be white crystalline powder with no odour and taste.
Table no 1: Physical properties of Azithromycin.
Sl. No Physical property Interpretation
1 Nature
Crystalline powder
2 Colour
White
3 Odour
Odourless
4 Taste
Tasteless
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B). Melting Point
Table no 2: Melting point of Azithromycin. The Melting point of Azithromycin was found to be 1130C by Capillary fusion method.
Method employed Capillary fusion method
Experimental value 113-1150C
Literature value 1130C
C). Solublity: The solubility of Azithromycin was determined in different solvent systems. An excess quantity of the drug was mixed with 10ml of each solvent in screw capped glass tubes. The solutions were examined physically for the absence or presence of drug particles for qualitative determination of drug Azithromycin was soluble in water and dilute solution of hydrochloric acid. It freely soluble in Dilute Hydrochloric acid and insoluble in water.
D). Determination of λmax: The absorption maximum of drug Azithromycin was found by using double beam UV spectrophotometer and it was 254nm.
E). Preparation of Calibration plot: Absorbance data for standard calibration curves are given in table 1. Using the absorbance of azithromycin at varied concentration, calibration curve was constructed. The calibration equation for straight line was observed to be Y=0.034x+0.005 with correlation coefficient as 0.999, this was further used for determination of concentration of unknown samples.
Table 3: Calibration data for calibration plot of azithromycin in 0.1N HCl (λmax=254nm).
Sl. No. Concentration(µg/ml) Absorbance(mean±SD)
1.
Blank
0.000±0.00
2.
2
0.071±0.08
3.
4
0.146±0.09
4.
6
0.210±0.07
5.
8
0.285±0.08
6.
10
0.351±0.07
7.
12
0.422±0.06
8.
14
0.494±0.01
9.
16
0.562±0.06
10.
18
0.620±0.09
11.
20
0.684±0.13
Fig 2: Standard Calibration Curve of Azithromycin in 0.1N HCl(λmax=254nm).
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F). Compatiblity studies of drug and polymer The FTIR Spectra of Azithromycin is shown in fig.
Fig no. 3: FTIR Spectra of Azithromycin drug.
2 Preliminary Studies During preliminary studies various polymers viz. HPMC K4M, HPMC K100M, Carbopol 934, were tried for formulating oral sustained release floating tablets of
azithromycin. Tablets were prepared using each of these polymers and using various polymers in different ratio. Subsequently depending upon the results obtained shown in table 8.
Table 4: Preliminary trial formulations.
Ingredients (mg/tablet)
F1
F2
F3
F4
F5 F6
Drug
500
500
500
500 500 250
HPMC K4M
80
-
-
50
50 200
HPMC K100M
-
80
-
100 100 -
Carbopol 934
-
-
80
-
60 -
Sod.bicarbonate
70
70
70
70
70 70
DCP
32
32
32
62
- 162
Mg.stearate
10
10
10
10
10 10
Table 5: Formulations development batches.
Ingredient
S1
S2 S3
S4
S5
S6
Azithromycin
250 250 250 250 250
250
HPMC K4M
150 200 125 100 100
140
HPMC K100M
50
-
-
100
70
60
Carbopol 934
-
-
75
-
30
-
DCP
145 145 145 145 145
145
Sod. bicarbonate
75
75 75
75
75
75
Mag.stearate
20
20 20
20
20
20
Talc
8
8
8
8
8
8
Aerosil
2
2
2
2
2
2
Evaluation of granules The prepared granules were evaluated by evaluating their Angle of Repose, Bulk density/Tapped density, Compressiblity index, Hausner ratio. The results for Formulation development batches are shown in table no. 10.
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Table no. 6: Resuls of precompression flow properties of granules of Azithromycin of Formulation development
batches.
Formulation code
Angle of repose(θ)
Bulk density (gm/cm3)
Tapped density (gm/cm3)
Carr’s index (%)
Hausner’s ratio(HR)
S1
30.12
0.2802
0.3356
16.50
1.19
S2
26.96
0.3162
0.3562
11.22
1.12
S3
31.27
0.2706
0.3046
11.16
1.12
S4
29.52
0.3262
0.3674
11.21
1.12
S5
28.30
0.3257
0.3821
14.76
1.17
S6
29.80
0.3002
0.3675
18.31
1.22
(n=3)
Preparation of floating matrix tablets of Azithromycin The granules were compressed into tablets using 16 station rotary tablet machine in biconvex shape.
Evaluation of floating matrix tablets of Azithromycin A). Physical Parameters The prepared tablets were evaluated for quality control tests like hardness, friability and drug content uniformity, weight variation. The results are shown in table. No.11.
Table 7: Result of physical parameters and drug content for all tablet formulations of azithromycin.
Hardness(kg/cm 2) Mean ±SD
(n=5± SD)
Friability (%)
Weight variation Mean ±SD (n=3±SD)
Drug content
(%)
Length(mm) Mean ±SD
Thickness (mm) Mean
±SD
S1
6.5±0.4
0.57
676.1±3.2
106.3±1.7 17.01±0.5
5.2±.002
S2
7.5±0.2
0.46
701.8±7.9
108.4±2.1 17.01±0.5
5.2±.005
S3
6.5±0.1
0.66
678.1±12.8
104.5±2.2 17.01±0.5
5.1±.003
S4
6.5±0.2
0.51
700.0±5.2
104.6±1.7 17.01±0.5
5.7±.005
S5
7.0±0.3
0.43
706.6±6.1
105.5±1.2 17.01±0.5
5.6±.004
S6
7.5±0.2
0.37
696.0±6.0
105.4±1.6 17.01±0.5
5.8±.002
(n=3)
B). Invitro studies I). Buoyancy test The results of in vitro buoyancy study and of formulation development batches are shown in table no. 12 and in Fig(1-7).
Table 8: Results of in vitro buoyancy study of formulation development batches of azithromycin floating tablets.
Formulation code
Floating lag time (sec) (n=3±SD)
Floating time(hrs)
S1
129±11
>12
S2
75±12
>12
S3
145±6
>8
S4
124±10
>12
S5
185±12
>10
S6
170±6
>12
(n=3)
The floating time for further optimized batches (S1-S6) was found to be in the ranged of (>8 to 12hrs). For the final optimized formulation (S2) floating lag time and floating time were found to e 75±12sec and 12hrs, respectively.
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Fig no 4: Floating properties of Azithromycin tablet S2 at 44 sec.
Fig no 5: Floating properties of Azithromycin tablet of S2 at47 sec.
Fig no 6: Floating properties of Azithromycin tablet S2 at 53 sec.
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Fig no 7: Floating properties of Azithromycin tablet S2 at 62 sec.
Fig no 8: Floating properties of Azithromycin tablet S2 at 66 sec.
Fig no 9: Floating properties of Azithromycin tablet S2 at 71 sec.
II). Swelling Index The swelling of the polymers used could be determined by water uptake of the tablet. The complete swelling was achieved at the end of 8hours, therefore percent swelling
index was determined at the end of 8hours for all the developed formulations. The values of swelling index of various batches were evaluated as shown in table and
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Fig. The swelling index of all the batches was found to be in the range of 86.48 to 98.40%.
Table no. 9: Results of in vitro Swelling index of formulation development batches of azithromycin floating
tablets.
Formulation code
Swelling index (%)after 8 hours
S1
93.56
S2
98.40
S3
88.97
S4
86.48
S5
90.77
S6
88.40
The swelling index of all the batches was found to be in the range of 86.48 to 98.40%.
Fig no 10: Swelling index of all the Formulations after 8hours.
Hence from above results the Swelling Index decreases as we increase the number of polymers. The formulation with maximum quantity of HPMC K4M formulation S2 shows the maximum swelling index 98.40%.
III). Dissolution Studies The dissolution studies were carried out by the procedure has explained earlier. The results of drug release data of all the formulations.
Table 10: In vitro drug release data of formulation S1.
Sl. No.
Time (hrs)
Square root of time
Log time
Cumulative* Percentage Drug
Release±SD
1
0
0.0000
2
2
1.4121
3
4
2.00
4
6
2.44
5
8
2.828
* Average of three determinations
0.301 0.602 0.778 0.903
0 48.90±1.32 63.21±2.79 80.61±2.97 95.18±4.36
Log Cumulative Percentage Drug Release
1.689 1.800 1.906 1.978
Cumulative Percent Drug
Remaining 100 51.10 36.79 19.39 4.82
Log Cumulative Percent drug Remaining
2.0000 1.708 1.565 1.287 0.683
Table 11: In vitro drug release data of formulation S2.
Sl. No.
Time (hrs)
Square root of time
Log time
Cumulative* Percentage Drug
Release±SD
1
0
0.0000
2
2
1.4121
3
4
2.00
4
6
2.44
5
8
2.828
6
10
3.162
7
12
3.464
* Average of three determinations.
0.301 0.602 0.778 0.903
1 1.07
0 23.70±2.10 48.65±3.76 52.62±1.99 69.27±4.66 73.47±3.87 89.71±2.78
Log Cumulative Percentage Drug Release
1.374 1.687 1.721 1.840 1.866 1.952
Cumulative Percent Drug
Remaining 100 76.30 57.15 51.38 30.73 26.53 10.29
Log Cumulative Percent drug Remaining
2.0000 1.882 1.757 1.710 1.487 1.423 0.012
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EUROPEAN
JOURNAL
OEFurPopHeaAnRJoMurAnCalEofUPThIaCrmAaLceutical
and
Medical
Research
Research
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AND MEDICAL RESEARCH
ISSN 2394-3211
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FORMULATION, EVALUATION AND CHARACTERIZATION OF FLOATING TABLET OF AZITHROMYCIN FOR HELICOBACTOR PYLORI
Neha Arora1, Yogesh Matta1, Dr. Sonu Sharma1, Saurabh Sharma1, Sandeep Singh1, Md Dabeer Ahmad2 1School of Pharmaceutical Sciences, Jaipur National University, Jagatpura, Jaipur.
2Department of Pharmaceutical Sciences, College of Pharmacy, Aldowadmi, Shaqra University KSA.
*Corresponding Author: Mr. Yogesh Matta Assistant Professor, School of Pharmaceutical Sciences, Jaipur National University, Jagatpura, Jaipur.
Article Received on 23/09/2019
Article Revised on 13/10/2019
Article Accepted on 02/11/2019
ABSTRACTS Oral route has been the most popular and successful route used for controlled delivery of drugs. Controlled release of drug delivery system (CRDDS) optimizes the biopharmaceutical, pharmacokinetic, pharmacodynamic, properties of drugs and to reduce the side effects and to designed to deliver the drug in such a way that the levels are maintained within the therapeutic window effective for a long period till the system continuous to deliver the drug at a particular rate. In present study, an attempt was made to formulate floating tablet of Azithromycin in order to enhance bioavailability, reduce dose thereby improve patient compliance. Preformulation studies were done to characterize the chemical and physical properties of drug. FT-IR spectrum and melting point determination confirmed identity and purity of Azithromycin. Azithromycin was subjected to compatibility studies with different excipients, there was no physical change observed in drug and excipients. Further, it was confirmed by taking FTIR graphs.
KEYWORDS: Azithromycin, Excipients, Pharmacokinetic, Pharmacodynamic, Bioavailability.
INTRODUCTION Oral Drug Delivery Systems Oral route has been the most popular and successfully used for controlled delivery of drugs because of convenience and ease of administration. The controlled release systems for oral use are mostly solids and based on dissolution, diffusion or a combination of both mechanisms in controlling the release rate of drug. During the past two decades, numerous oral delivery systems have been developed to act as drug reservoirs from which the active substance can be released over a
defined period of time at a predetermined and controlled rate. Drugs that are easily absorbed from the gastrointestinal tract and have a short half-life are eliminated quickly from the blood circulation. To reduce this problem, the oral controlled release (CR) formulations have been developed, as these will release the drug slowly into the GIT and maintain a constant drug concentration in the serum for a longer period of time. This minimizes several potential problems like saw-tooth kinetics characterized by large peaks and troughs in the drug concentration time curve.
A
B
Fig. 1: Plasma level profiles followings (A) Conventional and (B) Controlled release dosing.
Gastroretentive Drug Delivery Systems It has been suggested that formulating the drugs with narrow absorption window in a unique pharmaceutical
dosage form with gastroretentive properties, would enable an extended absorption phase of these drugs. After oral administration, such a dosage form would be retained in the
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Matta et al.
European Journal of Pharmaceutical and Medical Research
stomach and release the drug there in a extended manner, so that drug could be supplied continuously to its absorption sites in the upper gastrointestinal tract. Gastroretentive dosage form releases medications in a controlled manner which extends the absorption phase of drugs characterized by a limited and narrow absorption window at upper part of gastrointestinal tract or drugs intended to treat local ailments in gastroduodenum. The need for gastroretentive dosage forms has led to extensive efforts in both academia and industry towards the development of such drug delivery systems.
Gastroretentive technologies Various techniques have been pursued to increase the GRT of dosage forms by employing a variety of concepts such as floating, swelling, inflation and adhesion. These systems have been classified according to the basic principles of gastric retention. Floating drug delivery system (FDDS), with low
density providing sufficient buoyancy to float over the gastric contents. High density, which retain the dosage form in the body of stomach for longer period of time, by sedimenting to the folds of stomach. Bioadhesion to gastric mucosa, enabling the localized retention of the system in the stomach. Expansion by swelling or unfolding to a large size which limits emptying of the dosage form through pyloric sphincter.
Helicobacter pylori A peptic ulcer is a sore on the lining of the stomach or duodenum, the beginning of the small intestine. Less commonly, a peptic ulcer may develop just above the stomach in the oseophagus, the tube that connects the mouth to the stomach. A peptic ulcer in the stomach is called a gastric ulcer. One that occurs in the duodenum is called a duodenal ulcer.
People can have both gastric and duodenal ulcers at the same time. They also can develop peptic ulcers more than once in their lifetime. Peptic ulcers are common. Each year in the United States, about half a million people develop a peptic ulcer.
Causative agents for peptic ulcers A bacterium called Helicobacter pylori (H.pylori) is a major cause of peptic ulcers. Nonsteroidal antiinflammatory drugs (NSAIDs), such as asprin and ibuprofen, are another common cause.
Rarely, cancerous or noncancerous tumors in the stomach, duodenum, or pancreas cause ulcers. Peptic ulcers are not caused by stress or eating food, but both can make ulcer symptoms worse. Smoking and drinking alcohol also can worsen ulcers and prevent healing.
Life Cycle of H.Pylori H.pylori is a gram negative spiral shaped bacteria. In humans, it colonises the stomach and the likelihood of
infection increases with age. In the U.K, half of those over 50 are infected. There is some evidence that H.pylori may be associated with gastric cancer. There is no convincing evidence, at present, for a relation between H.pylori and non ulcer dyspepsia.
H.pylori infection by itself is not sufficient to cause peptic ulcers, other factors are needed. These may include hypersecretion of acid, smoking and genetic predisposition.
Helicobacter pylori is an important cause of peptic ulcer disease and chronic gastrititis and has been linked to the pathogensis of gastric malignancy. The bacterium causes peptic ulcers by damaging the mucous coating that protects the stomach and duodenum. Damage to the mucous coating allows powerful stomach acid to get through to the sensitive lining beneath. Together, the stomach acid and H.pylori irritate the lining of the stomach or duodenum and causes ulcer. For these reasons, anti-H.pylori regimens are being investigated with increasing frequency, with about 1500 reports being published between 1984 and 1999. Many combinations of antibiotics and antisecretory drugs have been tested in an attempt to find the optimal regimen. The regimen of choice should be cheap, simple, of short duration, associated with few side-effects, and with an efficacy of 90% or greater. The most popular strategies for producing a high rate (80-95%) of H.pylori eradication entail the use of two antibiotics given for atleast 1week. The use of antibiotics for shorter periods has been investigated infrequently, as a increased daily dose considered necessary is thought to be associated with an increase in side-effects.
Azithromycin is a potentially attractive therapeutic agent for H.pylori, given its excellent mean inhibitory concentration for this organism and long biological half life.
MATERIALS METHODS
Drug Profile
Common name: Azithromycin
Chemical
name:
(2R,3R,4R,5R,8R,10,11R,12S,13S,14R,)-11-
{[(2S.3R,4S,6R)-4-(dimethylamino)-
3hydroxy-6-
methyloxan-2-yl]oxy} -2-ethyl-3,4,10-trihydroxy-13-
{[(2R,4R,5S,6S)-5-hydroxy-
4-methoxy-4,6-
dimethyloxan-2-yl]oxy}-3,5,6,8,10,12,14-heptamethyl-1-
oxa-6azacyclopentadecan-15one.
Molecular formula: C38H72N2O12
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Structural formula
Molecular Weight: 748 Description: It is white or almost white crystalline powder. Solubility: Practically insoluble in water, freely soluble in ethanol and in methylene chloride. Therapeutic category: Antibiotic Melting point: 113-115°C Odour: Odourless
Mechanism
of
action:
Azithromycin
prevents bacteria from growing by interfering with
their protein synthesis It binds to the 50S subunit of the
bacterial ribosome,
and
thus
inhibits translation of mRNA. Nucleic acid synthesis is
not affected.
Uses: Azithromycin is used to treat many different infections, including acute otitis media, nonstreptococcal bacterial pharyngitis, gastrointestinal infections such as traveler's diarrhea, respiratory tract infections such as pneumonia, cellulitis.
Pharmacokinetics: Azithromycin is acid-stable, so it can be taken orally with no need of protection from gastric acids. It is readily absorbed, but its absorption is greater on an empty stomach. Time to peak concentration in adults is 2.1 to 3.2 hours for oral dosage forms and one to two hours after a dose. Due to its high concentration in phagocytes, azithromycin is actively transported to the site of infection. During active phagocytosis, large concentrations are released. The concentration of azithromycin in the tissues can be over 50 times higher than in plasma, due to ion trapping and its high lipid solubility(volume of distribution is too high).
Metabolism: According to Davis Drug Guide for Nurses, following a single 500 mg dose, the half-life of azithromycin is 11–14 h. The longer half-life of 68 h is achieved only when multiple doses are consumed. Biliary excretion of azithromycin, predominantly unchanged, is a major route of elimination. Over the course of a week, approximately 6% of the administered dose appears as unchanged drug in urine.
Side effects: Most common side effects are gastrointestinal: diarrhea (5%), nausea (3%), abdominal pain (3%), and vomiting. Fewer than 1% of patients stop taking the drug due to side effects. Nervousness, dermatologic reactions, and anaphylaxis have been
reported. As with all antimicrobial agents, pseudomembranous colitis can occur during and up to several weeks after azithromycin therapy.
METHODOLOGY Characterization of drug The procured sample of azithromycin was characterized in terms of its physical description, organoleptic properties, melting point and solubility in various solvents.
Establishment of calibration plot To conduct the drug dissolution studies, standard plots for pure drug were constructed by using method described by Preeti Gandhi et al. The absorbance of prepared solutions of azithromycin in 0.1N HCl was measured at 254nm in Shimadzu UV-1700 spectrophotometer against an appropriate blank (0.1N HCl).
Preliminary studies During preliminary studies various polymers viz. HPMC K4M, HPMC K100 and, Carbopol 934, were tried for formulating oral sustained release floating tablets of azithromycin. Tablets were prepared using each of these polymers and using various polymers in different ratio to formulate floating azithromycin tablets.
Preparation of granules Azithromycin was mixed with various grades of HPMC in varying ratio. These batches are mostly prepared by wet granulation method.
Evaluation of granules Angle of repose Flow properties of the granules are evaluated by determining the angle of repose. It is the maximum angle that can be obtained between the free standing surface of the powder heap and the horizontal plane. It is a qualitative assessment of the internal cohesive and frictional effects under low levels of external loading as might apply in powder mixing, on in tablet die or capsule shell filling operation. Tan θ = h/r
Bulk density The ratio of mass to volume is known as density of material. The bulk density is determined by pouring the weighed sample in to a graduated cylinder via a large funnel and measuring its volume.
Tapped density is determined by placing a graduated cylinder containing a non mass of formulation on a mechanical tapper apparatus which is operated at a fix no. of taps until the powder volume has reached a minimum. LBD and TBD were calculated using the following formula. LBD = weight of the powder / volume of the packing TBD = weight of the powder / tapped volume of the packing
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Compressibility index Compressibility index is a simple indication of the ease with a material can be induced to flow. The compressibility index and Hausner index are the measure of porosity of a powder to be compressed. They measure the relative importance of interparticulate interaction. For poorer flowing materials, there are frequently greater interparticulate interactions and greater difference between the bulk and tapped densities. These differences are reflected in the compressibility index and Hausner index.
Compressibility index of the powder was determined by Carr’s compressibility index as given by following eqn. Carr’s index (%) = [(TBD – LBD) x 100]/TBD
Hausner ratio Hausner ratio of the powder was determined by Hausner index as given by the following equation: Hausner index = TBD/LBD
Compression of granules The dried granules were first mixed with magnesium stearate and talc. The granules were then compressed into tablets of average weight 700 mg containing 250mg of azithromycin On a 16 station rotary tablet machine in biconvex shape.
Evaluation of floating tablets The prepared tablets were evaluated for quality control tests like hardness, thickness, friability and drug content uniformity, weight variation, thickness, in vitro dissolution studies and analysis of dissolution data, in vitro buoyancy test and swelling index determination.
Tablet hardness The mechanical strength of tablets is an important property. It has been described by various terms including fracture resistance, hardness, bending strength and crushing strength. Tablet hardness has been defined as the force required breaking a tablet in a diametric compression test.
Friability Friability test was done by Roche friabilator. Six tablets were weighed and were subjected to combined effect of attrition and shock by utilizing a plastic chamber that resolve at 25 rpm dropping the tablets at distance of 6 inch with each revolution. Operated for 100 revolutions, the tablets were dusted and reweighed. The percentage friability was calculated. The average hardness and standard deviation was determined. Percent friability = [(Weightfinal–Weightoriginal) / Weightoriginal] x 100
Uniformity of weight Twenty tablets from each batch were individually weighed and their average weight was calculated. From the average weight of the prepared tablets, the standard deviation was determined.
Drug content uniformity To evaluate a tablet’s potential for efficacy; the amount of drug per tablet needs to be monitored from tablet to tablet and batch to batch.
Thickness The dimensions of the tablet like thickness, length were measured using vernier-calipers. Ten tablets from each batch were selected randomly for this test and the average value was reported.
In vitro buoyancy test The in vitro buoyancy was determined by floating lag time, per the method described by Rosa et al. The tablets were placed in a 100 mL beaker containing as 0.1 N HCl. The time required for the tablet to rise to the surface and float was determined as Floating Lag Time (FLT) and the time period up to which the tablet remained buoyant is determined as Total Floating Time (TFT).
Swelling index determination The swelling behavior of dosage unit can be measured either by studying its dimensional changes, weight gain, or water uptake. Water uptake study of the dosage form is conducted by using dissolution apparatus-II in 900 mL of distilled water which is maintained at 37±0.5°C, rotated at 50 rpm. At selected regular intervals, the tablet is withdrawn and weighed. Swelling of the tablet is expressed as Swelling index (SI). The swelling index of optimized formulation was calculated using the formula shown in equation. SI= (W2 -W1) / W1
Fourier transform infra-red (FTIR) studies The FTIR spectra of the drug and its physical mixtures with polymer blend of selected best formulation were recorded in KBR using an FTIR spectrophotometer.
RESULTS AND DISCUSSION Preformulation Studies Characterization of drug A). Physical Description Azithromycin was found to be white crystalline powder with no odour and taste.
Table no 1: Physical properties of Azithromycin.
Sl. No Physical property Interpretation
1 Nature
Crystalline powder
2 Colour
White
3 Odour
Odourless
4 Taste
Tasteless
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B). Melting Point
Table no 2: Melting point of Azithromycin. The Melting point of Azithromycin was found to be 1130C by Capillary fusion method.
Method employed Capillary fusion method
Experimental value 113-1150C
Literature value 1130C
C). Solublity: The solubility of Azithromycin was determined in different solvent systems. An excess quantity of the drug was mixed with 10ml of each solvent in screw capped glass tubes. The solutions were examined physically for the absence or presence of drug particles for qualitative determination of drug Azithromycin was soluble in water and dilute solution of hydrochloric acid. It freely soluble in Dilute Hydrochloric acid and insoluble in water.
D). Determination of λmax: The absorption maximum of drug Azithromycin was found by using double beam UV spectrophotometer and it was 254nm.
E). Preparation of Calibration plot: Absorbance data for standard calibration curves are given in table 1. Using the absorbance of azithromycin at varied concentration, calibration curve was constructed. The calibration equation for straight line was observed to be Y=0.034x+0.005 with correlation coefficient as 0.999, this was further used for determination of concentration of unknown samples.
Table 3: Calibration data for calibration plot of azithromycin in 0.1N HCl (λmax=254nm).
Sl. No. Concentration(µg/ml) Absorbance(mean±SD)
1.
Blank
0.000±0.00
2.
2
0.071±0.08
3.
4
0.146±0.09
4.
6
0.210±0.07
5.
8
0.285±0.08
6.
10
0.351±0.07
7.
12
0.422±0.06
8.
14
0.494±0.01
9.
16
0.562±0.06
10.
18
0.620±0.09
11.
20
0.684±0.13
Fig 2: Standard Calibration Curve of Azithromycin in 0.1N HCl(λmax=254nm).
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F). Compatiblity studies of drug and polymer The FTIR Spectra of Azithromycin is shown in fig.
Fig no. 3: FTIR Spectra of Azithromycin drug.
2 Preliminary Studies During preliminary studies various polymers viz. HPMC K4M, HPMC K100M, Carbopol 934, were tried for formulating oral sustained release floating tablets of
azithromycin. Tablets were prepared using each of these polymers and using various polymers in different ratio. Subsequently depending upon the results obtained shown in table 8.
Table 4: Preliminary trial formulations.
Ingredients (mg/tablet)
F1
F2
F3
F4
F5 F6
Drug
500
500
500
500 500 250
HPMC K4M
80
-
-
50
50 200
HPMC K100M
-
80
-
100 100 -
Carbopol 934
-
-
80
-
60 -
Sod.bicarbonate
70
70
70
70
70 70
DCP
32
32
32
62
- 162
Mg.stearate
10
10
10
10
10 10
Table 5: Formulations development batches.
Ingredient
S1
S2 S3
S4
S5
S6
Azithromycin
250 250 250 250 250
250
HPMC K4M
150 200 125 100 100
140
HPMC K100M
50
-
-
100
70
60
Carbopol 934
-
-
75
-
30
-
DCP
145 145 145 145 145
145
Sod. bicarbonate
75
75 75
75
75
75
Mag.stearate
20
20 20
20
20
20
Talc
8
8
8
8
8
8
Aerosil
2
2
2
2
2
2
Evaluation of granules The prepared granules were evaluated by evaluating their Angle of Repose, Bulk density/Tapped density, Compressiblity index, Hausner ratio. The results for Formulation development batches are shown in table no. 10.
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Table no. 6: Resuls of precompression flow properties of granules of Azithromycin of Formulation development
batches.
Formulation code
Angle of repose(θ)
Bulk density (gm/cm3)
Tapped density (gm/cm3)
Carr’s index (%)
Hausner’s ratio(HR)
S1
30.12
0.2802
0.3356
16.50
1.19
S2
26.96
0.3162
0.3562
11.22
1.12
S3
31.27
0.2706
0.3046
11.16
1.12
S4
29.52
0.3262
0.3674
11.21
1.12
S5
28.30
0.3257
0.3821
14.76
1.17
S6
29.80
0.3002
0.3675
18.31
1.22
(n=3)
Preparation of floating matrix tablets of Azithromycin The granules were compressed into tablets using 16 station rotary tablet machine in biconvex shape.
Evaluation of floating matrix tablets of Azithromycin A). Physical Parameters The prepared tablets were evaluated for quality control tests like hardness, friability and drug content uniformity, weight variation. The results are shown in table. No.11.
Table 7: Result of physical parameters and drug content for all tablet formulations of azithromycin.
Hardness(kg/cm 2) Mean ±SD
(n=5± SD)
Friability (%)
Weight variation Mean ±SD (n=3±SD)
Drug content
(%)
Length(mm) Mean ±SD
Thickness (mm) Mean
±SD
S1
6.5±0.4
0.57
676.1±3.2
106.3±1.7 17.01±0.5
5.2±.002
S2
7.5±0.2
0.46
701.8±7.9
108.4±2.1 17.01±0.5
5.2±.005
S3
6.5±0.1
0.66
678.1±12.8
104.5±2.2 17.01±0.5
5.1±.003
S4
6.5±0.2
0.51
700.0±5.2
104.6±1.7 17.01±0.5
5.7±.005
S5
7.0±0.3
0.43
706.6±6.1
105.5±1.2 17.01±0.5
5.6±.004
S6
7.5±0.2
0.37
696.0±6.0
105.4±1.6 17.01±0.5
5.8±.002
(n=3)
B). Invitro studies I). Buoyancy test The results of in vitro buoyancy study and of formulation development batches are shown in table no. 12 and in Fig(1-7).
Table 8: Results of in vitro buoyancy study of formulation development batches of azithromycin floating tablets.
Formulation code
Floating lag time (sec) (n=3±SD)
Floating time(hrs)
S1
129±11
>12
S2
75±12
>12
S3
145±6
>8
S4
124±10
>12
S5
185±12
>10
S6
170±6
>12
(n=3)
The floating time for further optimized batches (S1-S6) was found to be in the ranged of (>8 to 12hrs). For the final optimized formulation (S2) floating lag time and floating time were found to e 75±12sec and 12hrs, respectively.
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Fig no 4: Floating properties of Azithromycin tablet S2 at 44 sec.
Fig no 5: Floating properties of Azithromycin tablet of S2 at47 sec.
Fig no 6: Floating properties of Azithromycin tablet S2 at 53 sec.
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Fig no 7: Floating properties of Azithromycin tablet S2 at 62 sec.
Fig no 8: Floating properties of Azithromycin tablet S2 at 66 sec.
Fig no 9: Floating properties of Azithromycin tablet S2 at 71 sec.
II). Swelling Index The swelling of the polymers used could be determined by water uptake of the tablet. The complete swelling was achieved at the end of 8hours, therefore percent swelling
index was determined at the end of 8hours for all the developed formulations. The values of swelling index of various batches were evaluated as shown in table and
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Fig. The swelling index of all the batches was found to be in the range of 86.48 to 98.40%.
Table no. 9: Results of in vitro Swelling index of formulation development batches of azithromycin floating
tablets.
Formulation code
Swelling index (%)after 8 hours
S1
93.56
S2
98.40
S3
88.97
S4
86.48
S5
90.77
S6
88.40
The swelling index of all the batches was found to be in the range of 86.48 to 98.40%.
Fig no 10: Swelling index of all the Formulations after 8hours.
Hence from above results the Swelling Index decreases as we increase the number of polymers. The formulation with maximum quantity of HPMC K4M formulation S2 shows the maximum swelling index 98.40%.
III). Dissolution Studies The dissolution studies were carried out by the procedure has explained earlier. The results of drug release data of all the formulations.
Table 10: In vitro drug release data of formulation S1.
Sl. No.
Time (hrs)
Square root of time
Log time
Cumulative* Percentage Drug
Release±SD
1
0
0.0000
2
2
1.4121
3
4
2.00
4
6
2.44
5
8
2.828
* Average of three determinations
0.301 0.602 0.778 0.903
0 48.90±1.32 63.21±2.79 80.61±2.97 95.18±4.36
Log Cumulative Percentage Drug Release
1.689 1.800 1.906 1.978
Cumulative Percent Drug
Remaining 100 51.10 36.79 19.39 4.82
Log Cumulative Percent drug Remaining
2.0000 1.708 1.565 1.287 0.683
Table 11: In vitro drug release data of formulation S2.
Sl. No.
Time (hrs)
Square root of time
Log time
Cumulative* Percentage Drug
Release±SD
1
0
0.0000
2
2
1.4121
3
4
2.00
4
6
2.44
5
8
2.828
6
10
3.162
7
12
3.464
* Average of three determinations.
0.301 0.602 0.778 0.903
1 1.07
0 23.70±2.10 48.65±3.76 52.62±1.99 69.27±4.66 73.47±3.87 89.71±2.78
Log Cumulative Percentage Drug Release
1.374 1.687 1.721 1.840 1.866 1.952
Cumulative Percent Drug
Remaining 100 76.30 57.15 51.38 30.73 26.53 10.29
Log Cumulative Percent drug Remaining
2.0000 1.882 1.757 1.710 1.487 1.423 0.012
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