Acta Poloniae Pharmaceutica ñ Drug Research, Vol. 68 No. 1 pp. 115ñ119, 2011 ISSN 0001-6837 Polish Pharmaceutical Society BIOEQUIVALENCE STUDY OF TWO BRANDS OF MELOXICAM TABLETS IN HEALTHY HUMAN PAKISTANI MALE SUBJECTS MAHMOOD AHMAD 1, GHULAM MURTAZA 2 *, NAVEED AKHTAR 1, FARYAL SIDDIQUE 1 and SHUJAAT ALI KHAN 1 1 Faculty of Pharmacy and Alternative Medicines, the Islamia University of Bahawalpur, Bahawalpur-63100, Pakistan 2 COMSATS Institute of Information Technology, Abbottabad, Pakistan Abstract: Meloxicam is a cyclooxygenase-2, preferential inhibitor non-steroidal anti-inflammatory drug (NSAID) and belongs to an enolic acid (oxicam) class used for the treatment of osteoarthritis and rheumatoid arthritis. The purpose of this single dose randomized cross-over study was to assess bioequivalence of two brands of oral meloxicam tablets (Xobix manufactured by Hilton Pharma (Pvt.) Ltd. as a reference and tablet Melfax by AGP (Pvt.) Ltd. as a test) in 18 healthy male volunteers in local population of Pakistan. The data obtained were subjected to non-compartment model pharmacokinetic analysis. The value of C max calculated in present study was 1.051 ± 3.762 µg/ml for reference formulation and 1.023 ± 4.102 µg/ml (the mean ± SEM) for test sample. The value of T max was 3.125 ± 1.004 h for reference standard and 3.750 ± 1.469 h (the mean ± SEM) for test sample. The area under the curve from zero to infinity (AUC 0-72) was 28.667 ± 0.414 µg h/ml for reference standard and 28.367 ± 0.333 µg h/ml for test sample (the mean ± SEM). The t 1/2 values were 13.694 ± 0.568 h and 13.319 ± 0.567 h (the mean ± SEM) for reference formulation and for test sample, respectively. The test formulation was found to be bioequivalent to reference formulation based on the pharmacokinetic parameters. Keywords: meloxicam, bioequivalence, non-compartment model Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used for the treatment of rheumatoid arthritis and osteoarthritis. However, gastrointestinal disturbances are the most frequently reported side effects of all NSAIDs, and include dyspepsia, gastric erosion, peptic ulcer formation and perforation, major upper gastrointestinal bleeding, inflammation and permeability changes of the intestine and lower bowel (1, 2). Consequently, there is a considerable need for a clinically effective NSAID with an improved safety profile, especially in terms of gastrointestinal side effects. Meloxicam is an enolcarboxamide non-steroidal anti-inflammatory drug with a selective inhibition of cyclooxygenase-2 (COX-2) (3, 4). The drug is less likely to adversely affect the cytoprotective function of arachidonic acid metabolites formed by COX-1 in the gastric mucosa or prostaglandin (PGE 2 ) in the kidney. In a global analysis of studies conducted with meloxicam in patients with rheumatoid arthritis and osteoarthritis, this drug has displayed a favorable gastrointestinal profile, compared to NSAIDs, e.g., piroxicam, naproxen and diclofenac (5ñ7). Meloxicam has bioavailability of 89% after oral administration, is strongly bound to plasma proteins and its half life (t 1/2 ) is 20ñ24 h which allow once daily administration. Meloxicam is nearly completely metabolized and undergoes excretion with approximately half the administered dose eliminated renally, with the remainder excreted in feces (8). The time to reach maximum concentration (T max ) after a 7.5 mg dose under fasted and fed conditions ranged from 4ñ5 h and 5ñ6 h, respectively. If the dose is increased to 30 mg, T max will be prolonged to 9ñ11 h (3, 9). Chemical structure of meloxicam is shown in Figure 1. In Pakistan, yet no study has been conducted on bioequivalence of meloxicam. Consequently, it was very important to conduct the pharmacokinetics and bioavailability studies of meloxicam in the local population. This project was therefore designed to determine the bioequivalence parameters of meloxi- * Corresponding author: e-mail: ma786_786@yahoo.com; phone: 92629255243; fax: 92629255565 115
116 MAHMOOD AHMAD et al. Table 1. Two way crossover design Treatment Group Period 1 Period 2 I A B II B A Figure 1. Chemical structure of meloxicam cam in domestic situation to ensure the rational usage and safety of this valuable medicinal agent. EXPERIMENTAL Chemicals and Reagents Meloxicam was gifted by AGP, Pakistan. Methanol (HPLC grade), o-phosphoric acid (85%) and hydrochloric acid were purchased from Merck, Germany. Di-sodium hydrogen phosphate was purchased from Riedel-de-Haen, England. All other chemicals and solvents were of analytical grade and used without any further purification. Methods The study was an open, single dose, cross-over complete two period of treatment dosing. Written informed consent was obtained from each subject before commencement of study. Eighteen healthy human male volunteers (age limit 20ñ26 years and body weight range 63ñ87 kg) were scheduled to participate in the study. Each volunteer received single dose of meloxicam (15 mg orally) separated by 2- week washout period. After dosing, serial blood samples were collected for a period of 72 h. Plasma was harvested and analyzed for meloxicam by a modified HPLC method. Formulations Test: Melfax Æ (meloxicam) 15 mg tablets, AGP, Karachi-Pakistan. Reference:Xobix Æ (meloxicam) 15 mg tablets, Hilton Pharma, Karachi- Pakistan. Experimental design The ethics of study was approved by the Board of Advanced Studies and Research, the Islamia University of Bahawalpur, Pakistan. Randomized two way cross over design was adopted for the study as given in Table 1. The volunteers were divided into two groups, 9 in each. The four volunteers of one group received single oral dose of 15 mg of meloxicam tablets (Xobix Æ, Hilton Pharma as a reference product designated as A), whereas the other four received 15 mg of meloxicam tablets (Melfax Æ, AGP Pvt. as a test product designated as B) in the treatment at first period. In the second period, reverse of the first period was administered. The single dose drug regimen was administered on an empty stomach and volunteers were housed at the study center from 1 h before to 72 h after the dosing. Each volunteer was instructed to fast overnight prior to the treatment visit. The volunteers were allowed to drink water at libitum. Each volunteer was provided with standardized breakfast two hours after the dosing. They were also provided the lunch and evening refreshment. A washout period of 14 days was allowed before the start of the second period. Sample collection A 20-gauge venous brannula was inserted into forearm for collection of blood samples. A blood sample was collected before drug was given (zero time) and then at 0.5, 1.0, 2.0, 3.0 4.0, 6.0, 8.0, 12.0, 24.0, 36.0, 48.0, 60.0 and 72.0 hours after dosing of meloxicam tablets (10). A 5 ml blood sample was collected each time. Blood samples were centrifuged at 3500 rpm for 10 min and plasma was collected and separated into labeled vials. The plasma samples were kept frozen at ñ20 O C until analysis (11). Extraction procedure Extraction procedure was comprising of precipitation method. In extraction procedure, 1 ml of plasma sample was in glass centrifuge tube and 100 µl of 1 M HCl was added. Protein was precipitated out and vortex mixed for one minute then centrifuged at 4000 rpm for 20 min. Supernatant layer was taken and filtered through 0.45 µm Millipore filter, evaporated under the stream of nitrogen at ambient temperature, then reconstituted with 100 µl of the mobile phase and 20 µl were injected on the column for analysis (11).
Bioequivalence study of two brands of meloxicam tablets in healthy human male subjects 117 High performance liquid chromatography (HPLC) Analysis was performed by using Perkin Elmer Liquid Chromatograph, with a pump series 200 and Perkin Elmer UV detector set at 346 nm. A reverse phase system was used consisting of C 18 column (150 mm 5 µm particle size 4.6 mm I.D.). The mobile phase consisted of methanol : phosphate buffer (50 mm) (60:40, v/v). The ph of mobile phase was adjusted with ortho-phosphoric acid (85%) to 3.5 and the phase was degassed by passing nitrogen gas for about 2ñ3 min. The mobile phase was pumped at a rate of 1.0 ml/min. Injections of 20 µl volume were injected with a run time of 10 min (12). Safety analysis Health assessment including vital signs, physical examination and clinical laboratory testing was performed before and seven days after study. Subjects were interviewed at the beginning and end of each study period and were monitored throughout of the confinement period to determine any adverse events potentially related to study medication of procedures. Pharmacokinetic analysis Pharmacokinetic analysis was performed by using non-compartmental method of analysis by using Kinetica Æ 4.0 program. Statistical analysis Paired t-test was used to calculate the difference whether significant (p < 0.05) or insignificant (p > 0.05) between the values of the bioparameters of the two different brands of meloxicam, Xobix Æ and Melfax Æ. The confidence level was set at 95%. RESULTS AND DISCUSSION Maximum plasma concentration (C max ) The peak plasma drug concentration C max represents maximum plasma drug concentration obtained after oral administration of drug. In the present study, the (the mean ± SEM) maximum plasma concentration (C max ) for reference and test product was found to be 1.051 ± 0.3762 µg/ml and 1.023 ± 0.4102 µg/ml, respectively. This difference was not significant (p > 0.05) and shows that both the brands were bioequivalent. The value for C max in the present study has been found in good agreement with the previous studies conducted in healthy human volunteers. In these studies conducted in healthy male volunteers (8), maximum plasma concentration (C max ) was 1.72 mg/l with 18.8% coefficient of variation with a single oral dose of 30 mg of capsules. The higher value of C max may be due to higher dose, i.e., 30 mg. The C max reported in another study after a single oral dose of 15 mg in healthy subjects (the mean ± SD) was 1.20 ± 0.24 µg/ml (13). So by calculations of the dose, the value of C max calculated in this study was found similar to that given in the literature. There was statistically non-significant difference (p > 0.05) between the values of C max of both the brands. Time of peak plasma concentration (T max ) The time of peak plasma concentration (T max ) corresponds to the time required to reach maximum drug concentration after drug administration. At T max peak drug absorption occurs and the rate of drug absorption exactly equals to the rate of drug elimination (11). In the present study, T max values of reference product and test product were 3.125 ± 1.004 h and 3.750 ± 1.469 h, respectively. Statistically non significant difference (p > 0.05) was found in the values of T max of both the brands. These values for T max (the mean ± SEM) are in good agreement with the previously reported values of T max (after a single oral dose of 15 mg in healthy subjects) 4.365 ± 1.17 h (14), and 5.6 ± 3.2 h (the mean ± SD) (13). Another study (15), after a single oral dose of 15 mg in healthy subjects has reported a value of T max as 6.3 ± 2.6 h and 5.3 ± 2.5 h (the mean ± SD) for test and reference product, respectively. The absolute bioavailability of meloxicam tablets was 89% following a single oral dose of 30 mg. The mean maximum plasma concentration (C max ) was achieved within 4ñ5 h after a 7.5 mg meloxicam tablet taken under fasted conditions, indicating prolonged drug absorption. Area under curve (AUC) Area under the curve (AUC) reflects the total amount of drug that reaches the systemic circulation (11). AUC is directly proportional to the dose of the drug. As dose of the drug increases, AUC also increases. In the present study, the value of AUC 0-72 (the mean ± SEM) for the reference product and test product were 28.667 ± 0.414 µg h/ml and 28.367 ± 0.333 µg h/ml, respectively. A statistically non significant (p > 0.05) difference was found between the values of AUC 0-72 of both the brands. In a previous study conducted on human volunteers (13), AUC 0-8 (the mean ± SD) was found to be 29.17 ± 7.06 µg h/ml which is in agreement with the values of AUC in the present study.
118 MAHMOOD AHMAD et al. Table 2. Comparison of the mean ± SEM of bioavailability and pharmacokinetic parameters of Xobix Æ -Hilton and Melfax Æ -AGP administered in an oral dose of 15 mg in normal subjects. Parameters Xobix Æ -Hilton Melfax Æ -AGP (the mean ± SEM) (the mean ± SEM) C max (µg/ml) 1.051 ± 0.3762 1.023 ± 0.4102 ns T max (h) 3.125 ± 1.004 3.750 ± 1.469 ns AUC 0- (µg h/ml) 28.667 ± 0.414 28.367± 0.333 ns AUC 0-t (µg h/ml) 28.385 ± 0.411 28.067± 0.331 ns ns = non significant difference (p < 0.05) t 1/2 (h) 13.694 ± 0.568 13.319 ± 0.567 ns Figure 2. Comparison of plasma concentration vs. time profile of Xobix Æ -Hilton and Melfax Æ -AGP plotted on rectangular co-ordinate graph, administered in the oral dose of 15 mg to 8 subjects. Half life (t 1/2 ) It is the time required by a drug to become one half of its original concentration in the plasma (11). In the present study, the plasma half life of reference and test products were 13.694 ± 0.568 h and 13.319 ± 0.567 h (the mean ± SEM), respectively. A statistically non significant (p > 0.05) difference was found between the values of AUC 0- of both the brands. These values are in agreement with the previous findings of 19.300 h of meloxicam in healthy subjects after oral dose of 15 mg capsule (16). Another study conducted on healthy volunteers using 30 mg tablet has reported t 1/2 value of 17.5 h (1). A study was also conducted using two different tablets of 15 mg in healthy volunteers. The t 1/2 (the mean ± SEM) reported was 19.953 ± 1.05 h and 19.050 ± 1.04 h for both the formulations, respectively (14). The half-lives of both the brands show no difference (p > 0.05) when compared statistically. Comparison of the mean ± SEM of bioavailability and pharmacokinetic parameters of Xobix Æ - Hilton and Melfax Æ -AGP administered in the oral dose of 200 mg in normal subjects is in Table 2 and comparison of plasma concentration versus time profile of Xobix Æ -Hilton and Melfax Æ -AGP plotted on rectangular co-ordinate graph, administered in the oral dose of 15 mg in 8 subjects is presented in Figure 2. The elimination half-life (t 1/2 ) of meloxicam is approximately 20 h. This is reflected in a total plasma clearance (Cl T ) of 0.4ñ0.7 L/kg. Steady-state plasma concentrations are achieved within 3ñ5 days. CONCLUSION The results of reference and test brands showed that both these brands possess almost the same bioavailability and pharmacokinetic parameters. Therefore, on the basis of the values of pharmacokinetic and bioavailability parameters, it can be concluded that both the brands are bioequivalent and can be used as pharmaceutical substitute with each other.
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