The Pharmaceutical equivalence and stability of multisource metronidazole suspensions

Abstract

Background: To determine the pharmaceutical equivalence and stability of eighteen randomly selected brands of metronidazole suspensions. Methods: The tests conducted include ease of re dispersibility, sedimentation volume, particle size measurements, viscosity and assay of drug content. Results: The results showed that 16 (88.9%) out of 18 brands including the innovator (SR) were re-dispersed between 30seconds to one minute, while 2 (11.1%) took more than two minutes. The sedimentation volume for 15 (83.3%) of the brands was less than 0.50 while the innovator brand had a significantly higher (p<0.001) value (0.91). The particle size of the brands ranged between 1.942 and 5.921/mi and the sedimentation rate were between 20-50mL/day. The viscosity of the brands was significantly different (p<0.05) with SA, SB, SC, SD, SE and SF having 250-400cp, brands SG, SH, SI, SM, SP and SQ had 10-50cp while the remaining six brands had l(X)-190cp. Four brands including the innovator (SK, SP, SQ and SR) met Pharmacopeial requirement for metronidazole suspension on drug content. Moreover, color change, reduced viscosity and significant increase (p<0.05) in particle sizes were observed for samples stored at 42°C for seven weeks while those stored at 4°C and 25°C maintained stability. Conclusion: Four out of eighteen brand s of metronidazole suspensions evaluated in this study were found to be pharmaceutically equivalent. The stability studies showed that there is the need to adhere strictly to storage of metronidazole suspensions in a cool place.