Amox 500 tablet

Prescribed for Bacterial Infection, Bacterial Endocarditis Prevention, Anthrax Prophylaxis, Actinomycosis, Lyme Disease - Erythema Chronicum Migrans, Upper Respiratory Tract Infection.

Interchangeability of Two 500 Mg Amoxicillin Capsules with One 1000 Mg Amoxicillin Tablet After a Single Oral Administration. College of Pharmacy, An-Najah National University, Nablus, Palestine.

1 Department of Pharmaceutical Sciences, Ferrara University, Ferrara.

2 Pharmacare Chemical and Cosmetics, Ramallah, Palestine.

College of Pharmacy, An-Najah National University, Nablus, Palestine.

The aim of the study was to evaluate if two capsules (Amoxil ® capsules, 500 mg/capsule) and one tablet (Amoxicare ® tablets, 1000 mg/tablet) of amoxicillin have similar bioequivalence parameters.

For this purpose a randomized, two-way, crossover, bioequivalence study was performed in 24 healthy, male volunteers, divided into two groups of 12 subjects each.

One group was treated with the reference standard (Amoxil ® ) and the other one with the generic tablet Amoxicare ® , with a crossover after a wash-out period of 7 days. Blood samples were collected at fixed time intervals and amoxicillin was determined by a validated HPLC method.

The pharmacokinetic parameters AUC 0-8 , AUC 0-? , C max , T max , K e and T 1/2 were determined for both formulations and statistically compared to evaluate the bioequivalence between the two brands of amoxicillin, using the statistical model recommended by the FDA.

C max and AUC 0-? were statistically analyzed using analysis of variance (ANOVA); no statistically significant difference was observed between the two formulations. The 90% confidence intervals between the mean values of C max and AUC 0-? fall within the FDA specified bioequivalent limits (80-125%) suggesting that the two products are bioequivalent and the two formulations are interchangeable. Based on these findings it was concluded that the practice of interchangeability between the above formulations to achieve better patient compliance could be followed without compromising the extent of amoxicillin absorption. Wt: 365.41; ? max : 230-273.8 nm, ethanol; LogP: 0.91; fig. 1 ) is a commonly prescribed orally available ?-lactam antibiotic with moderate antibacterial spectrum that is available on the market as different dosage forms and in strengths.

For instance, it is available as 1000 mg tablet and as 500 mg capsules. The question of whether two 500 mg capsule can be substituted with one 1000 mg tablet is not uncommon and pharmacists face such problem frequently with many other prescribed medications. Possible reasons for substitution include the following; (i) the prescribed original brand or the dosage is not available in pharmacy as the case in many developing countries, (ii) difference in the price of the prescribed dosage form and (iii) better swallowing characteristics especially for elderly patients. The later reason is of particular importance as swallowing problems can cause poor patient compliance. In fact, some studies have indicated that some dosage forms are preferred over others by elderly patients.

For example, capsules are preferred over tablets when large amount of active ingredient is to be swallowed[1]. In fact, the rugged surface of some tablets may scratch the esophagus during intake[2].

Indeed, damage of esophagus by retention of tablet has been reported[3]. Furthermore, some tablets have strong smell or taste.

All these factors may make the administration of tablets an uncomfortable experience leading to poor patient compliance. In such cases, substitution of large volume tablet with two capsules containing the same drug strength can solve problems associated with swallow ability. However, bioequivalence problems may arise especially when the substitution was carried out between liquid and solid oral dosage forms, or between soft elastic gelatin capsules and tablets[4].

On the other hand, bioequivalence cannot be compromised when two solid dosage forms such as hard gelatin capsules and tablets where interchanged.

Few publications are found in literature demonstrating potential interchangeability of two different solid dosage forms based on pharmacokinetic data[5,6].

The aim of the present study was to determine if the practice of interchangeability between two amoxicillin capsules (Amoxil ® , 500 mg/capsule) and one amoxicillin tablet (Amoxicare ® , 1000 mg/tablet) in order to achieve better patient compliance can be conducted without compromising their extent of absorption. Acetonitrile HPLC grade, methanol HPLC grade and tetra-n-butyl ammonium hydroxide were from Merck, (Darmstadt, Germany); chloroform HPLC grade was from Fisons Scientific Equipments, UK; sodium dihydrogen phosphate dihydrate (NaH 2 PO 4 ·2H 2 O) was from Riedel de Haen, (Seelze, Germany); double distilled high purity water was used.

The HPLC grade solvents acetonitrile and methanol were used as received. Amoxicillin and Paracetamol (internal standard) were supplied by Pharmacare Chemical and Cosmetics (Ramallah, Palestine).

Amoxicare ® tablet (1000 mg amoxicillin/tablet, batch number RD-23E03) was from Pharmacare Chemical and Cosmetics.

Amoxil ® capsules (500 mg/capsule, batch number 040605) were manufactured by Medical Union Pharmaceuticals Co, Abou

Sultan

The whole study followed the requirements of the Declarations of Helsinki and was conducted in accordance with the current Good Clinical Practice (GCP), International Conference Harmonization (ICH) as well as Good Laboratory Practice (GLP) Guidelines. Each volunteer had signed the informed consent form after ample information and consideration time has been provided.

Twenty-four adult male volunteers, non-smokers, aged between 17-30 y, weighing between 59 and 85 kg, mox 500 mg were chosen to participate in the present study. The volunteers were not on concomitant medications and they were free from significant cardiac, hepatic, renal, pulmonary, gastrointestinal, neurological or hematological disease as determined within four weeks prior to the beginning of the study by way of medical histories and physical examinations. Subject’s health status was determined following a physical examination, laboratory tests and medical history by a qualified registered MD physician.

The physician reviewed all preclinical laboratory tests for each subject. Exclusion criteria included extreme weight ranges (overweight or underweight), anemia, liver or renal dysfunction, parasitic and other diseases or conditions that was judged to affect the absorption, distribution and/or elimination of amoxicillin. The subjects were asked to abstain from taking drugs and alcohol for at least 3 days prior to the test and throughout the entire study period.

However, it has to be underlined that the drugs eventually used by the involved volunteers are characterized by short half life values and thus do not overlap with amoxicillin during the first day of study. On the night before starting the study, the volunteers were instructed to fast for at least 10 h before drug administration.

The study had an open randomized two-period crossover design with a 7-day washout period between doses. The volunteers were randomly divided into two equal groups each of 12 subjects.

The first group was given the reference formulation and the second group received the test formulation with a crossover after a washout period of one week.

On the morning of the experiment, 10 ml of blood sample was withdrawn from each volunteer to serve as a blank for the drug assay. Each of the 24 volunteers then took one Amoxicare ® tablet (1000 mg amoxicillin) as the test drug or two Amoxil ® capsules (500 mg amoxicillin each) as the reference drug followed by 200 ml of water. Five milliliters blood samples for plasma drug assay were collected from an indwelling catheter inserted in the antecubital vein of one of the arms.

Samples were obtained at 0.0 (blank sample), 0.25, 0.5, 0.75, 1, 1.5, 2, 2.5, 3, 4, 6, 8 h after drug administration, in heparinized tubes.

Plasma was directly separated by centrifugation at 3000 rpm for 10 min and stored at -20° until analyzed. Four hours after drug administration, the subjects were allowed to eat a standard breakfast of bread, jam, low-fat white cheese, water (150 ml). They were then allowed controlled access to fruit juice and other non-alcoholic beverages. The volunteers had their second meal (standard lunch containing grilled chicken, rice and vegetables) 4 h later.

Stock solution of amoxicillin (500 µg/ml) was prepared by dissolving 50 mg of drug in methanol.

Working standard solutions were prepared from the stock solution by serial dilution with methanol to prepare seven working solutions of amoxicillin with concentrations of 5, 10, 20, 50, 100, 200 and 500 µg/ml.

Stock solution of paracetamol (internal standard) was prepared by dissolving the drug powder in methanol to give 50 µg/ml. Stock and working standard solutions were protected from light and stored at -20° until use.

The

calibration

standards

The calibration standards were treated with 1 ml of acetonitrile and shaken for 1 min, then centrifuged at 3000 rpm for 7 min. The supernatant was transfered to clean test tube and 5 ml of chloroform was added, shacked for one minute, and then centrifuged at 3000 rpm for 7 min. The upper layer was separated and 50 µl was injected into the HPLC column.

For the analysis of the samples, 0.5 ml of each study sample was transferred to a clean test tube spiked with the internal standard. The study samples were treated as the calibration standards after addition of the internal standard.

Under the chromatographic conditions described above, the retention time of amoxicillin and the internal standard (paracetamol) were 4.8±0.5 and 6.0±0.5 min, respectively.

Analytical validation report for HPLC method used for the quantification of amoxicillin in human plasma is described below. The analyses were performed using an HPLC system equipped with a variable wavelength UV detector and an automatic injector was used in this study Waters 2690 Separation Modules, Waters Corporation, Milford Massachusetts, USA. Separation was accomplished with a 250?4.6 mm 5 µm Hypersil ® BDS C 18 column, Thermo Fisher Scientific Inc, Waltham, United States.

The mobile phase used consists of 94% buffer and 6% acetonitrile, where buffer is a mixture of tetra-n-butyl ammonium hydroxide (0.15 g/l) in sodium dihydrogen phosphate dehydrate (20 mM). The flow rate was 1.2 ml/min, the UV detector was set at 225 nm and the peak areas were calculated using the Millennium data analysis program (Millennium Consultants Inc, NJ, USA).

Quantification of amoxicillin was obtained by plotting amoxicillin to internal standard peak area ratios as a function of concentration. For statistical analysis a Minitab statistical Package version 13 on IBM PC was used. The validation of this chromatographic analytical method was performed in order to evaluate its linearity, selectivity, stability, precision and accuracy.

Calibration curves were constructed from the peak area ratio (drug/ internal standard) and the corresponding amoxicillin concentration in each calibration standard.

The linearity study was carried out in the range of concentrations between 0.5 to 50 µg/ml. To assess linearity, drug free plasma was spiked with known amounts of the drug to achieve the concentration of 0.5, 1.0, 2.0, 5.0, 10, 20 and 50 µg/ml.

The correlation coefficient was always greater than 0.99 during the course of the validation.

METHOD VALIDATION PARAMETERS OF AMOXICILLIN ANALYSIS.