Amphotericin B, aminoglycosides, and hypomagnesaemic tetany

Electrolyte and Acid-Base Disorders Triggered by Aminoglycoside or Colistin Therapy: A Systematic Review

Aminoglycoside or colistin therapy may alter the renal tubular function without decreasing the glomerular filtration rate. This association has never been extensively investigated. We conducted a systematic review of the literature following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses recommendations. Databases searched included United States National Library of Medicine, Excerpta Medica, and Web of Science. For the final analysis, we evaluated 46 reports, published after 1960, describing 82 cases. A total of 286 electrolyte and acid-base disorders were reported. Hypomagnesemia, hypokalemia, and hypocalcemia were reported in more than three quarter of cases. Further disorders were, in decreasing order of frequency, metabolic alkalosis, hyponatremia, hypophosphatemia, hypouricemia, hypernatremia, and metabolic acidosis. Six electrolyte and acid-base disorders were reported in seven cases, five in 12 cases, four in 16 cases, three in 31 cases, two in 11 cases, and one in five cases. Laboratory features consistent with a loop of Henle/distal tubular dysfunction were noted in 56 (68%), with a proximal tubular dysfunction in three (3.7%), and with a mixed dysfunction in five (6.1%) cases. The laboratory abnormality was unclassified in the remaining 18 (22%) cases. Treatment with aminoglycosides or colistin may trigger a proximal tubular or, more frequently, a loop of Henle/distal tubular dysfunction.

Drug-induced hypomagnesaemia : scope and management

Nearly 50 medications have been implicated as inducing hypomagnesaemia, sometimes based on insufficient data regarding clinical significance and frequency of occurrence. In fact, clinical effects attributed to hypomagnaesemia have been reported in only 17 of these drugs. A considerable amount of literature relating to individual drugs has been published, yet a comprehensive overview of this issue is not available and the hypomagnesaemic effect of a drug could be either overemphasised or under-rated. In addition, there are neither guidelines regarding treatment, prevention and monitoring of drug-induced hypomagnesaemia nor agreement as to what serum level of magnesium may actually be defined as 'hypomagnesaemia'. By compiling data from published papers, electronic databases, textbooks and product information leaflets, we attempted to assess the clinical significance of hypomagnesaemia induced by each drug. A practical approach for managing drug-induced hypomagnesaemia, incorporating both published literature and personal experience of the physician, is proposed. When drugs classified as inducing 'significant' hypomagnesaemia (cisplatin, amphotericin B, ciclosporin) are administered, routine magnesium monitoring is warranted, preventive treatment should be considered and treatment of hypomagnesaemia should be initiated with or without overt clinical manifestations. In drugs belonging to the 'potentially significant' category, among which are amikacin, gentamicin, laxatives, pentamidine, tobramycin, tacrolimus and carboplatin, magnesium monitoring is justified when either of the following occurs: clinical manifestations are apparent; persistent hypokalaemia, hypocalcaemia or alkalosis are present; other precipitating factors for hypomagnesaemia coexist; or treatment is with more than one potentially hypomagnesaemic drug. No preventive treatment is required and treatment should be initiated only if hypomagnesaemia is accompanied by symptoms or clinically significant relevant laboratory findings. In those drugs whose hypomagnesaemic effect is labelled as 'questionable', including furosemide and hydrochlorothiazide, routine monitoring and treatment are not required.

Transient hypoparathyroidism due to amphotericin B-induced hypomagnesemia in a patient with beta-thalassemia

OBJECTIVE

To report a case of transient hypoparathyroidism that developed in a beta-thalassemic patient due to amphotericin B-induced hypomagnesemia. CASE SIJMMARY: A 21-year-old man with beta-thalassemia was treated with amphotericin B for Candida albicans intravenous line sepsis. After five days of treatment (cumulative dose 160 mg), he developed hypomagnesemia, which caused hypoparathyroidism and hypocalcemia; all three abnormalities resolved after the drug was withdrawn.

DISCUSSION

Patients with beta-thalassemia may develop endocrinologic abnormalities due to excessive iron deposition. Some may have subclinical hypoparathyroidism that clinically emerges after even a mild homeostasis disturbance. Amphotericin B is associated with variable adverse effects including renal tubular insult, which may induce hypomagnesemia following relatively short treatment. The resolution of hypomagnesemia, hypocalcemia, and hypoparathyroidism in our patient after discontinuation of amphotericin B treatment suggests that the endocrine dysfunction was due to a drug-related adverse effect and not to parathyroid dysfunction caused by iron deposition.

CONCLUSIONS

This case demonstrates a known but rarely reported adverse effect of amphotericin B, namely hypomagnesemia, that may occur even at a low cumulative dose. It also emphasizes that patients with an underlying disease, such as thalassemia, may be more susceptible to hypoparathyroidism and hypocalcemia during treatment with amphotericin B.

Amiloride prevents amphotericin B related hypokalaemia in neutropenic patients

Twenty neutropenic patients with various haematological disorders were randomised prospectively to receive either intravenous amphotericin B alone or amphotericin B and oral amiloride 5 mg twice a day for treatment of confirmed or suspected fungal infection. Patients receiving amiloride had a significantly higher plasma potassium (p less than 0.01), a significantly lower urinary potassium loss (p less than 0.01), and required significantly less potassium chloride supplementation to maintain their plasma potassium within the normal range (p less than 0.001). Amiloride was well tolerated, had no clinically important side effects, and provided effective control of plasma potassium in patients treated with amphotericin B.