Class of 2011 Abstract / OBJECTIVES: To investigate if the drug content of several different antibiotic products, obtained in Mexico, fall within the USP specification range for a given drug. METHODS: Ten antibiotic products containing either amoxicillin, ampicillin, ciprofloxacin, or sulfamethoxazole/trimethoprim were obtained from three random pharmacies in Mexico. The concentrations of the active ingredient(s) in these antibiotics were determined by high performance liquid chromatography, utilizing assays from the USP monographs for each drug. Weight variation within each product was also considered. Ten units from each product were analyzed. RESULTS: More than half of the capsules for each of the amoxicillin lots analyzed were outside of the acceptable USP limits (90-120% label claim) with the average calculated % label claim for each being 89.96 and 87.25%, respectively. One lot of ampicillin had two capsules out of range, while all of the capsules tested from the second lot were within the specification range. Both lots of ciprofloxacin passed. For the sulfamethoxazole/triemthoprim tablets, the sulfamethoxazole content for each lot was in range, however 20-30% of the units analyzed were out of range for trimethoprim. Interestingly, weight variation within each product was less than 3% RSD for all products, with the exception of the ampicillin lot which had two capsules out of spec (% RSD- 6.14). CONCLUSION: Most of the Mexican acquired antibiotics had content uniformity that fit within the USP guidelines. Although amoxicillin displayed significant variability, the capsules fell outside of the USP limits by a slim margin. While these findings are not a representation of all antibiotics obtained from Mexico, they do suggest the importance of continued research of the quality of internationally obtained products.