Effect of standard-dose trimethoprim/sulfamethoxazole on the serum potassium concentration in elderly men.

OBJECTIVE: To determine the effect of standard-dose trimethoprim/sulfamethoxazole (TMP/SMX) (TMP 160 mg and SMX 800 mg q12h) on the serum potassium concentration. DESIGN: Retrospective and concurrent study. SETTING: A Veterans Affairs Medical Center. PATIENTS: Fifty-three men hospitalized at the Fargo Veterans Affairs Medical Center. Thirty-three patients who received standard-dose TMP/SMX for 3 or more days comprised the study group. Twenty patients who received oral cephradine or amoxicillin for 3 or more days comprised the control group. Patients who received potassium supplements, potassium-sparing diuretics, angiotensin-converting enzyme inhibitors, nonsteroidal antiinflammatory drugs, beta-blockers, heparin, known nephrotoxic agents, patients with a serum creatinine concentration of more than 177 mumol/L, and patients with baseline hyperkalemia (serum potassium concentration > 5.1 mmol/L) were excluded. RESULTS: The serum potassium concentration in the study group was 4.22 +/- 0.40 mmol/L and increased by 0.31 +/- 0.38 mmol/L at the end of therapy (p < 0.001). Twenty-six patients in the study group (78.8%) had an increase in the serum potassium concentration during TMP/SMX therapy. Fourteen of these patients had follow-up serum potassium concentrations obtained after completion of therapy. The serum potassium concentration returned to baseline in 10 of these patients. The serum creatinine concentration also increased during therapy. However, the correlation between the increase in the serum potassium concentration and the increase in the serum creatinine concentration was weak (Pearson r = 0.29). The serum potassium in the control group was 4.34 mmol/L and remained essentially unchanged during therapy. CONCLUSIONS: Therapy with standard-dose TMP/SMX is associated with a slight increase in the serum potassium concentration. Routine monitoring of the serum potassium concentration in patients who are treated with standard-dose TMP/SMX therapy is unnecessary. However, TMP/SMX should be considered as a possible cause of unexplained hyperkalemia in elderly patients receiving TMP/SMX therapy.

An outbreak of watermelon-borne pesticide toxicity.

The largest reported United States outbreak of illness caused by a foodborne pesticide was due to aldicarb-contaminated watermelons. In Oregon, where the first episodes of toxicity were reported, 264 reports were received, and 61 definite cases were identified. Residues of aldicarb, a cholinesterase inhibitor, were found in 10 of 16 tested melons which had been eaten by persons meeting the case definition. The outbreak demonstrates the need for enhanced physician vigilance with respect to anticholinesterase intoxication. It also demonstrates the value of an established system for reporting of unusual illness to public health officials.

Rate of transfer of DDT from the blood compartment.

CONCLUSIONS: The rate of decline of DDT from the blood has been shown to be quite rapid and recovery of pesticide from the blood has been related to the recovery of lipid from the blood.