Acetazolamide-induced adynamic ileus

Abstract

Acetazolamide is a carbonic anhydrase inhibitor diuretic, the prototype of sulfonamide-derived drugs. Its most common clinical use is in the preoperative treatment of closed angle glaucoma and continuation therapy of open angle glaucoma [1, 2] and of secondary glaucoma. We report a case of a 75-year-old man with a history of hypertension controlled with a combination of amiloride (5 mg) and hydrochlorothiazide (50 mg). He reported regular bowel habits, and there was no past history of gastrointestinal disease. He had no complaints of constipation or abdominal pain. Two months before, he had a cataract extraction from the right eye. Ten days after the surgery, he complained of pain in the eye, and was found to have uncontrolled inflammatory glaucoma with high-intraocular pressure (32 mmHg). Therefore, acetazolamide 125 mg/bid and prednisone 25 mg/day were prescribed. Mid-epigastric abdominal cramp pains associated with constipation appeared 2 days after the start of therapy. Symptoms progressively grew worse, limiting the patient’s feeding, so after a week the acetazolamide was stopped by the patient. The abdominal pain gradually disappeared in about 3 days, and the patient got back to feeding regularly, and the alvus returned to normal. With the exception of these drugs, he did not take any other therapies. The ophthalmologist continued therapy with prednisone (12.5 mg/day) and added tobramycin (3 mg) and dexamethasone (1 mg) collyrium, but after a week the high-intraocular pressure (42 mmHg) recurred, so the acetazolamide (250 mg/bid) was resumed, and the patient was admitted to hospital. During the following 24 h constipation, abdominal cramp pain recurred with increasingly severe and located in the mid-epigastrium and in the right iliac fossa. The physical examination revealed a tender abdomen in all quadrants without the signs of peritonitis, and with no peristalsis detectable. Laboratory tests showed only an increased C-reactive protein (5.6 mg/dl). An electrocardiogram and chest X-ray were normal. An abdominal Xray series showed coprostasis and diffuse air-fluid levels. Assuming that the adynamic ileus was due to the acetazolamide, the drug was discontinued, and a liquid diet, intravenous hydration and enemata were started. Mannitol (200 cm i.v. per bid) was prescribed to reduce the ocular hypertension. Symptoms progressively reduced and disappeared in 48 h, with the reappearance of bowel sounds, and disappearance of the distention. An abdominal X-ray series confirmed the absence of coprostasis and air-fluid levels. After 1 month, in a follow-up control, no sign of gastrointestinal disease was found. Acetazolamide (Diamox ) is a carbonic anhydrase inhibitor used in the treatment of glaucoma, epileptic seizures, benign intracranial hypertension (pseudotumor cerebri), altitude sickness, cystinuria and dural ectasia [1, 2]. The carbonic anhydrase form a family of enzymes that catalyze the rapid conversion of carbon dioxide to bicarbonate and protons, a reaction that occurs rather slowly in the absence of a catalyst [1, 3]. The active site of most carbonic anhydrases contains a zinc ion; they are therefore classified as metalloenzymes. Carbonic anhydrases are wide-spread zinc enzymes, present in mammals in at least M. Gallerani (&) M. Coletti B. Boari Division of Internal Medicine, Department of Medicine, St. Anna Hospital, Corso Giovecca 203, 44100 Ferrara, Italy e-mail: m.gallerani@ospfe.it