Severe Hyperkalemia in a Geriatric Patient Receiving Standard Doses of Trimethoprim-Sulfamethoxazole

Trimethoprim-associated electrolyte and acid-base abnormalities

INTRODUCTION

The antimicrobial trimethoprim is structurally related to potassium-sparing diuretics and may consequently lead to derangements in electrolyte and acid-base balance. Since no report so far analyzed the literature documenting individual cases with electrolyte and acid-base derangements induced by trimethoprim, a systematic review was carried out.

EVIDENCE ACQUISITION

We retained 53 reports documenting 68 cases (42 males and 26 females 23 to 96 years of age) of electrolyte or acid-base derangements occurring on trimethoprim for about 5 days.

EVIDENCE SYNTHESIS

One hundred five electrolyte imbalances were detected in the 68 patients: hyperkalemia (>5.0 mmol/L) in 62 (91%), hyponatremia (<135 mmol/L) in 29 (43%) and metabolic acidosis (pH<7.38 and bicarbonate <19 mmol/L) in 14 (21%) cases. Following possible predisposing factors for electrolyte and acid-base abnormalities were found in 54 (79%) patients: high-dose trimethoprim, comedication with drugs that have been associated with electrolyte and acid-base derangements, preexisting kidney disease, age ≥80 years and diabetes mellitus.

CONCLUSIONS

High-dose trimethoprim, comedicated with drugs that have been associated with electrolyte and acid-base derangements, poor kidney function, age ≥80 years and diabetes mellitus predispose to trimethoprim-associated electrolyte and acid-base abnormalities. Clinicians must recognize patients at risk, possibly avoid drug combinations that may worsen the problem and monitor the laboratory values.

Antimicrobial-associated renal tubular acidosis

OBJECTIVE

To review the literature documenting the association of various antimicrobial medications with the development of renal tubular acidosis (RTA).

DATA SOURCES

A search of the English literature via MEDLINE (1966-November 2003) and International Pharmaceutical Abstracts (1970-November 2003) was conducted to identify human reports of RTA associated with various drugs from all available classes of antimicrobial agents. Major search terms included renal tubular acidosis, acidosis, antibiotics, and antimicrobials. Bibliographies of selected articles were also searched to identify additional reports of RTA.

STUDY SELECTION AND DATA EXTRACTION

Case reports, observational studies, and experimental studies documenting the association of any antimicrobial agent with the development of RTA were included.

DATA SYNTHESIS

Antimicrobial-associated RTA is a relatively uncommon adverse effect, with most reports involving amphotericin B, trimethoprim/sulfamethoxazole, and outdated tetracycline. These agents may induce RTA either through direct tubular toxicity or as a function of their pharmacologic action. The time course for the development of RTA varies depending on the antimicrobial utilized. In most instances, RTA is reversible; however, some patients may experience prolonged recovery after the offending agent is removed.

CONCLUSIONS

Given that antimicrobial-associated RTA is a relatively uncommon adverse effect, review of the patient's drug regimen may reveal these agents as otherwise unrecognized causes of RTA. Likewise, underlying causes of RTA other than medications must be ruled out. Diagnosing antimicrobial-induced RTA may be difficult, given many of these agents may be used in combination and some are intrinsically nephrotoxic.