Simultaneous determination of trimethoprim and sulfamethoxazole in dried plasma and urine spots.

BACKGROUND: Trimethoprim-sulfamethoxazole (TMP-SMX) is an antimicrobial drug combination commonly prescribed in children and adults. The study objectives were to validate and apply an HPLC-MS/MS method to quantify TMP-SMX in dried plasma spots (DPS) and dried urine spots (DUS), and perform a comparability analysis with liquid matrices. RESULTS: For TMP the validated range was 100-50,000 ng/ml for DPS and 500-250,000 ng/ml for DUS; for SMX, the validated range was 1000-500,000 ng/ml for both DPS and DUS. Good agreement was noted between DPS/DUS and liquid plasma and urine samples for TMP, while only modest agreement was observed for SMX in both matrices. CONCLUSION: A precise, accurate and reproducible method was developed to quantify TMP-SMX in DPS and DUS samples.

Urinary biomarkers of trimethoprim bioactivation in vivo following therapeutic dosing in children.

The antimicrobial trimethoprim-sulfamethoxazole (TMP-SMX) is widely used for the treatment of skin and soft-tissue infections in the outpatient setting. Despite its therapeutic benefits, TMP-SMX has been associated with a number of adverse drug reactions, which have been primarily attributed to the formation of reactive metabolites from SMX. Recently, in vitro experiments have demonstrated that TMP may form reactive intermediates as well. However, evidence of TMP bioactivation in patients has not yet been demonstrated. In this study, we performed in vitro trapping experiments with N-acetyl-l-cysteine (NAC) to determine stable markers of reactive TMP intermediates, focusing on eight potential markers (NAC-TMP adducts), some of which were previously identified in vitro. We developed a specific and sensitive assay involving liquid chromatography followed by tandem mass spectrometry for measurement of these adducts in human liver microsomal samples and expanded the methodology toward the detection of these analytes in human urine. Urine samples from four patients receiving TMP-SMX treatment were analyzed, and all samples demonstrated the presence of six NAC-TMP adducts, which were also detected in vitro. These adducts are consistent with the formation of imino-quinone-methide and para-quinone-methide reactive intermediates in vivo. As a result, the TMP component of TMP-SMX should be considered as well when evaluating adverse drug reactions to TMP-SMX.

Bioequivalence study of three generic formulations of co-trimoxazole tablets in human urine.

Many proprietary and generic formulations of co-trimoxazole tablets commercially marketed in Nigeria are mostly from Asian countries. Nigerians buy these products because of their cheaper prices but not confident with regards to therapeutic, quality, safety, and efficacy. Health professionals usually are cautious about drug product selection and substitution during prescription and dispensing. In this paper, the bioequivalence study of three multi-sourced (generic) co-trimoxazole tablets was carried out on the urine of twelve healthy volunteers. The reversed-phase high performance liquid chromatography was employed for the analysis. Sulphadoxine was used as internal standard. The limits of detection were 76.3 ng/mL for trimethoprim, and 61.9 ng/mL for sulphamethoxazole at 0.16 aufs. The linearity (n = 5) for the calibration curve was of the order, 1.0000 for trimethoprim and 0.9998 for sulphamethoxazole; percentage recoveries for trimethoprim and sulphamethoxazole were 89.4 and 87.9% respectively. The relative bioavailabilities of the two generics to the innovator's product were 104.2% (trimethoprim) and 106.8% (sulphamethoxazole); 114.8% (trimethoprim) and 111.8% (sulphamethoxazole) for a product of reputable pharmaceutical company in Nigeria and Indian product respectively. In conclusion, the three generic formulations of co-trimoxazole tablets were biologically equivalent. Interchangeability of drugs in prescription and dispensing may be recommended in this situation.

Compliance with cotrimoxazole prophylaxis for the prevention of opportunistic infections in HIV-positive tuberculosis patients in Thyolo district, Malawi.

OBJECTIVE: To verify compliance with cotrimoxazole prophylaxis in human immunodeficiency virus (HIV) infected tuberculosis (TB) patients during the continuation phase of anti-tuberculosis treatment, and to assess the sensitivity, specificity and positive predictive values of verbal verification and pill counts as methods of checking compliance. DESIGN: Cross-sectional study. METHODS: Cotrimoxazole compliance was assessed in a cohort of TB patients who were attending four TB follow-up centres during the continuation phase of anti-TB treatment between months 4 and 6. Verbal verification of drug intake, physical verification of pill count balance, and urine trimethoprim detection by gas chromatography and mass spectrometry were used for assessing compliance. RESULTS: Using urine trimethoprim detection as the gold standard for compliance, trimethoprim was detected in 82 (94%) of 87 patients in the cohort. Verbal verification of cotrimoxazole intake and objective pill count balances showed high sensitivity and positive predictive values compared with the gold standard of urine trimethoprim detection. CONCLUSIONS: In a rural district in Malawi, compliance with cotrimoxazole as an adjunct to anti-tuberculosis treatment in HIV-infected TB patients was good, and can be assessed simply and practically by verbal verification and pill counts.

Antibiotic activity in microbiological media versus that in human urine: comparison of ampicillin, ciprofloxacin, and trimethoprim-sulfamethoxazole.

The activities of three antibiotics in both Mueller-Hinton broth (MHB) and pooled human urine were compared by using an in vitro pharmacodynamic model. Clinical and reference strains of Escherichia coli were exposed to antibiotics at concentrations achievable in human urine. The rate of bacterial killing (time to a reduction of 3 log10 CFU/ml) and the extent of bacterial killing at 24 h were examined. Between MHB and urine, there were no significant differences in the rate or extent of bacterial killing for both ampicillin and ciprofloxacin. For trimethoprim-sulfamethoxazole there was no significant difference in the extent of bacterial killing in urine compared with that in MHB (P > 0.1); however, there was a significant decrease in the rate of bacterial killing in urine compared with that in MHB (P < 0.001). We conclude that with ampicillin and ciprofloxacin, activity against E. coli in MHB is predictive of the effects in human urine. The activity of trimethoprim-sulfamethoxazole in MHB predicts the extent but not the rate of bacterial killing in human urine.

Antibiotic treatment of otitis media with effusion.

There are various forms of medical treatment for otitis media with effusion (OME) in children. One of these is a four week course of an antibiotic. A trial was carried out comparing cotrimoxazole with amoxicillin-potassium clavulanate in 102 cases with 181 affected ears. In addition this trial used various procedures to increase and monitor compliance, and the results showed that the compliant cases did much better than the noncompliant cases and cotrimoxazole was more effective than amoxicillin-potassium clavulanate. When the ethnic groupings were analysed the compliance was lower for the Maori (24%) and Pacific Islander (29%) than the European (49%). The success rate for the compliant cases whose middle ear effusion resolved in one or both ears had a similar result with Maori (40%), Pacific Islander (60%) and European (71%) probably indicating an increased nonmeasured compliance in the latter.