The Quality of Essential Antimicrobial and Antimalarial Drugs Marketed in Rwanda and Tanzania: Influence of Tropical Storage Conditions on in Vitro Dissolution

J Clin Pharm Ther. 2004 Aug;29(4):331-8. doi: 10.1111/j.1365-2710.2004.00568.x.


Objective: The quality of 33 formulations of essential antimicrobial and antimalarial drugs (amoxicillin capsules, metronidazole tablets, sulfamethoxazole/trimethoprim tablets, quinine tablets and sulphadoxine/pyrimethamine tablets) marketed in Rwanda and Tanzania was assessed and the influence of tropical storage conditions on potency and in vitro dissolution investigated.

Methods: Drug content and in vitro dissolution were determined immediately after purchase and during 6-month storage under simulated tropical conditions (75% relative humidity, 40 degrees C) using the methods described in the USP 24 monographs on the drugs concerned.

Results and discussion: At the time of purchase, the drug content of all the formulations was within the limits recommended by the USP 24, but after 6-month storage, the drug content of one sulfamethoxazole/trimethoprim and one quinine formulation were found to be substandard. Immediately after purchase, four formulations (three sulfamethoxazole/trimethoprim and one sulphadoxine/pyrimethamine combination) failed the USP 24 dissolution test. Except for three metronidazole and one quinine formulations, dissolution tests performed after 6 months of storage under simulated tropical conditions showed that drug release remained within the USP 24 recommended values.

Conclusion: In both countries, essential drug formulations met pharmacopoeial potency requirements, but some had a poor in vitro drug release profiles. Some of the formulations tested were not stable upon storage under simulated tropical conditions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Infective Agents / standards*
  • Antimalarials / standards*
  • Chemistry, Pharmaceutical*
  • Drug Stability*
  • Drug Storage*
  • Humidity / adverse effects
  • Quality Control
  • Rwanda
  • Tanzania
  • Tropical Climate


  • Anti-Infective Agents
  • Antimalarials