Drugs and the kidney

This article on drug nephrotoxicity is detailed, as it is important to be fully aware of renal side-effects of drugs with regard to prevention andearly diagnosis in order to manage the condition correctly. Many therapeutic agents are nephrotoxic, particularly when the serum half-life isprolonged and blood levels are raised because of decreased renal excretion. Distal nephrotoxicity is markedly enhanced when the glomerularfiltration rate (GFR) is reduced and is a particular threat in elderly patients with so-called ‘normal’ creatinine levels. In patients of 45 - 55 years of age theGFR is reduced by about 1 mL/min/year, so that an otherwise healthy person of 80 may have an estimated GFR (eGFR) of <60 mL/min or <50 mL/min,i.e. stage 2, 3 or 3b chronic kidney disease (CKD). Furthermore, other effects related to kidney dysfunction may be seen, e.g. worsening of hypertensionwith the use of non-steroidal anti-inflammatory drugs, increased bruising or bleeding tendency with aspirin, and hyponatraemia hypertensionacidosis with angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers. Digoxin is contraindicated in stage 3 CKD, even ina reduced dosage. Other drugs can cause the direct formation of kidney stones, e.g. topiramate (used in the prophylaxis of resistant migraine).Levofloxacin (Tavanic) can cause rupture of the Achilles tendon and other tendons.Radiocontrast media must be used with care. Occasionally, strategies to prevent acute kidney insufficiency cause irreversible CKD,especially in patients with diabetes and those with myeloma who have stage 4 - 5 CKD. Gadolinium in its many forms (even the newerproducts) used as contrast medium for magnetic resonance imaging is best avoided in patients with stages 4 and 5 CKD