Antihypertensive Pharmacobezoar

Abstract

Most antihypertensive drugs have known side effects that are elicited by the careful clinician taking care of hypertensive patients. However, many antihypertensive medications utilize drug delivery systems that prolong the duration of blood pressure reduction. The gastrointestinal therapeutic system that is used with nifedipine, isradipine, and verapamil has a unique side effect. Obstruction may occur at the site of a previous surgical repair (pyloric stenosis or gastroplasty) or stenosis of the esophagus, small intestine, or colon. The same delivery system is used with methylphenidate, oxy‐butynin, glipizide, and doxazosin. Although this complication is rare, physicians who prescribe and care for hypertensive patients should recognize this potential problem.

Forensic Features of Pharmacobezoars

“…The gastrointestinal therapeutic system (GITS) was developed as a diffusion system to allow the delivery of drugs such as nifedipine at a constant rate, thus allowing daily dosing . The GITS system is also used in slow release preparations of verapamil, doxazosin, methylphenidate, oxybutynin, glipizide, and isradipine . Tablets are surrounded by a semipermeable cellulose acetate membrane which incorporates a single hole; underlying this is an outer layer of the “active agent”, such as nifedipine and an inner “driving agent” layer of polyethylene oxide which absorbs water, expands, and expresses the active ingredient through the single hole in the shell at a constant rate .…”

Venlafaxine Pharmacobezoar Causing Intestinal Ischemia Requiring Emergent Hemicolectomy

“…Pharmaceuticals, including extended- or sustained-release (SR) products, with significant unabsorbable components, are prone to bezoar formation. For example, nifedipine SR products consist of an insoluble cellulose acetate shell that is excreted whole [5]. Finally, massive tablet ingestions, regardless of formulation, have caused pharmacobezoars [6, 7].…”

Curse of the ghost pills: the role of oral controlled-release formulations in the passage of empty intact shells in faeces. Two case reports and a literature review relevant to psychiatry

“…Some manufactures specifically advise not to prescribe certain CR formulations if patients have a history of GI narrowing [Prisant and Spaulding, 2006]. CR formulations can be a source of false positives on physical investigations, such as barium enema, and may appear as polyps on an endoscopy [Prisant and Spaulding, 2006]. Clinicians need to be aware and well informed of the pros and cons related to CR formulations to be able to inform patients and others and to be able to practice safely given that CR medications are frequently prescribed and newer ones will be appearing on the market.…”