Renal Disorders

Reports, particularly in the European literature, have described the occurrence of renal calculi in chronic ephedrine users (107-111). A review of cases from a large commercial laboratory specializing in the analysis of kidney stones found that 200 out of 166,466, or 0.064%, of stones analyzed by that laboratory, contained either ephedrine or pseudoephedrine. Unfortunately, the analytic technique used could not distinguish ephedrine from pseudoephedrine, and because pseudoephedrine is used so much more widely than ephedrine, it seems that the risk of renal calculus associated with ephedrine use must be quite small (110). There have been no new reports of ephedrine-related nephrolithiasis since 1999. Direct toxicity, with altered renal function and demonstrable kidney lesions related to ephedrine use, has never been demonstrated. Urinary retention, occurring as a consequence of drug overdose, was occasionally reported (112,113), but additional cases have not been described in more than a decade. The FDA and Commission E both warn against the possibility of urinary retention in patients with prostatic enlargement, but the theoretical basis for this concern is unclear, and, in any case, retention in patients with prostate disease has not been reported.

Small amounts of ephedrine are oxidized in to norephedrine and norpseudoephedrine in the liver (24,73). In patients with diminished renal function, these drugs may accumulate and have the potential to cause serious toxicity. None of the ephedrine enantiomers are easily removed by dialysis, and treatment of overdose remains supportive, using pharmacological antagonists to counter the a- and p-adrenergic effects of these drugs (114). Because excretion is pH-dependent, patients with renal tubular acidosis are also at risk (115). The FDA reports having received a number of accounts of hematuria after use of ephedra-based products, but no such cases have ever appeared in the peer-reviewed literature, and review of the reports published by the FDA shows that all of the affected individuals were taking multiple remedies, some capable of causing interstitial nephritis.

51 Tips for Dealing with Kidney Stones

51 Tips for Dealing with Kidney Stones

Do you have kidney stones? Do you think you do, but aren’t sure? Do you get them often, and need some preventative advice? 51 Tips for Dealing with Kidney Stones can help.

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