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Comparative pharmacokinetic and in-vitro antimicrobial activity of two different brands of rifampicin
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released from the MC in gastric fluid in l/2 hour and over 95%in 4 hours. In simulated intestinal fluid onIy 58% of the total drug was released over 24 hours. The slow release of AZT in the simulated intestinal fluid indicates that controlled release MC formulation of AZT would be an effective and practical method for decreasing the dosii frequency in AIDS patients.
Garg, SK., Chakrabarti, A., Panigrahi, D., Sharma, M., Talwar, P., Kumar, N. and Sharma, P.L. Departments of Pharmacology and Medical Microbiology, Postgraduate Institute of Medical Edacation and Research, Chandigarh 160 012. India
A comparative study on the bioavailability and in-vitro antimicrobial activity was under taken between a new formulation of rifampicin (Famcin) produced by Indian DN~S and Pharmaceuticals Ltd and a standard brand of rifampicin (R-Cin) of Lupin Laboratories Ltd to ensure the quality of the new formulation of rifampicin. A cross over pharmacokinetic study was canied out on eight healthy male volunteers with a washout period of eight days between the treatments. The mean age of volunteers was 32 (range 25-47) years; mean height 169.15 (range 162-180) cm and mean weight of 66 (range 52-78) kg. The pharmacokinetic study was carried out at two dose levels i.e. 300 mg and 450 mg given orally under both single dose and steady state conditions. Plasma rifampicin was assayed spectrophotometrically (McConnell et al., 1979). For in-vitro antimicrobial activity the microbiological assay was carried out to determine the relative minimum inhibitory concentrations (MIC) using several strains of two test organisms viz. Staphylococcus aureus and Mycobacterium tuberculosis. The MIC was determined using agar dilution method (Reeves et a, 1978). The results of pharmacokinetic parameters with the single dose of 300 mg showed significant increase in area under the plasma concentration time curve of Famcin (25.66 f 4.98 mcg/ml.h) as compared to R-Cin (13.01 f 1.76 mcg/ml.h). However, no significant difference was observed in Cmax, Tmax and elimination half-life of both the formulations. No significant difference was observed in any of the pharmacokinetic parameters after a single oral dose of 450 mg of Famcin and R-Cin. The steady state kinetics also showed no significant difference in any of the pharmacokinetic parameters i.e. AUC O-a, Cmax, Tmax and elimination half-life at 300 mg and 450 mg dose levels. In the in-vitro antimicrobial study, MIC of Famcin was found to be significantly less as compared to R-Cin in suppressing the growth of test organisms. These results suggest that Famcin and R-Cin have comparable rate and extent of bioavailability and elimination half-life when compared at similar dose levels. However, Famcin has greater antimicrobial activity as compared to
R-Cin. Reference5 McConnell,J.B., Smith, H., Davies, M. and Williams,R., 1979. Br. J. Clin. Pharmac.8. 506. Reeves, D.V., Philips, I., Williams, J.D. and Wise, R., 1978. Laboratory Methods in Antimicrobial Chemotherapy(1st edn). Churchill,Livingstone.
released from the MC in gastric fluid in l/2 hour and over 95%in 4 hours. In simulated intestinal fluid onIy 58% of the total drug was released over 24 hours. The slow release of AZT in the simulated intestinal fluid indicates that controlled release MC formulation of AZT would be an effective and practical method for decreasing the dosii frequency in AIDS patients.
Garg, SK., Chakrabarti, A., Panigrahi, D., Sharma, M., Talwar, P., Kumar, N. and Sharma, P.L. Departments of Pharmacology and Medical Microbiology, Postgraduate Institute of Medical Edacation and Research, Chandigarh 160 012. India
A comparative study on the bioavailability and in-vitro antimicrobial activity was under taken between a new formulation of rifampicin (Famcin) produced by Indian DN~S and Pharmaceuticals Ltd and a standard brand of rifampicin (R-Cin) of Lupin Laboratories Ltd to ensure the quality of the new formulation of rifampicin. A cross over pharmacokinetic study was canied out on eight healthy male volunteers with a washout period of eight days between the treatments. The mean age of volunteers was 32 (range 25-47) years; mean height 169.15 (range 162-180) cm and mean weight of 66 (range 52-78) kg. The pharmacokinetic study was carried out at two dose levels i.e. 300 mg and 450 mg given orally under both single dose and steady state conditions. Plasma rifampicin was assayed spectrophotometrically (McConnell et al., 1979). For in-vitro antimicrobial activity the microbiological assay was carried out to determine the relative minimum inhibitory concentrations (MIC) using several strains of two test organisms viz. Staphylococcus aureus and Mycobacterium tuberculosis. The MIC was determined using agar dilution method (Reeves et a, 1978). The results of pharmacokinetic parameters with the single dose of 300 mg showed significant increase in area under the plasma concentration time curve of Famcin (25.66 f 4.98 mcg/ml.h) as compared to R-Cin (13.01 f 1.76 mcg/ml.h). However, no significant difference was observed in Cmax, Tmax and elimination half-life of both the formulations. No significant difference was observed in any of the pharmacokinetic parameters after a single oral dose of 450 mg of Famcin and R-Cin. The steady state kinetics also showed no significant difference in any of the pharmacokinetic parameters i.e. AUC O-a, Cmax, Tmax and elimination half-life at 300 mg and 450 mg dose levels. In the in-vitro antimicrobial study, MIC of Famcin was found to be significantly less as compared to R-Cin in suppressing the growth of test organisms. These results suggest that Famcin and R-Cin have comparable rate and extent of bioavailability and elimination half-life when compared at similar dose levels. However, Famcin has greater antimicrobial activity as compared to
R-Cin. Reference5 McConnell,J.B., Smith, H., Davies, M. and Williams,R., 1979. Br. J. Clin. Pharmac.8. 506. Reeves, D.V., Philips, I., Williams, J.D. and Wise, R., 1978. Laboratory Methods in Antimicrobial Chemotherapy(1st edn). Churchill,Livingstone.