A 65-year-old male is undergoing rehabilitation after a stroke. Ten days ago, he presented to the emergency department with abrupt onset of left upper and lower extremity weakness. He has a history of hypertension, hypercholesterolemia, gastroesophageal reflux disease and hypothyroidism. He does not use tobacco, alcohol or illicit drugs. His blood pressure is 140/90 mm Hg and pulse is 72/min. He has weakness and increased tone in the left upper and lower extremities. You prescribe diazepam to this patient in order to decrease muscle spasticity of involved extremities. This patient should primarily be cautioned to avoid which of the following drugs?

Question

A 65-year-old male is undergoing rehabilitation after a stroke.  Ten days ago, he presented to the emergency department with abrupt onset of left upper and lower extremity weakness.  He has a history of hypertension, hypercholesterolemia, gastroesophageal reflux disease and hypothyroidism.  He does not use tobacco, alcohol or illicit drugs.  His blood pressure is 140/90 mm Hg and pulse is 72/min.  He has weakness and increased tone in the left upper and lower extremities.  You prescribe diazepam to this patient in order to decrease muscle spasticity of involved extremities.  This patient should primarily be cautioned to avoid which of the following drugs?

Quizplus · Accepted Answer

Diazepam is a long-acting benzodiazepine indicated as follows: The most common side effect of diazepam is sedation. Diazepam may also impair coordination and balance (sometimes avoided in the elderly for fear of falls), decrease memory and concentration, and produce confusion. These effects are amplified by the co-administration of other CNS-depressants. As a class, all benzodiazepines should be excluded from use in conjunction with alcohol, barbiturates, neuroleptics, or 1^st generation antihistamines. Among drugs listed in the answer choices, only chlorpheniramine causes sedation and should not be used with diazepam. Chlorpheniramine is a 1^st generation antihistamine that acts by blocking both central and peripheral H1 receptors. Chlorpheniramine and other 1^st generation antihistamines can be very sedating because they easily penetrate the blood-brain barrier and accumulate in the CNS. The most sedating of this generation of antihistamines are diphenhydramine (Benadryl), promethazine, and hydroxyzine. Despite the associated sedation, these antihistamines are often still used to prevent/treat allergic reactions and motion sickness and as antiemetics. (Choice B) Loratadine is a second-generation antihistamine that blocks peripheral H1 histamine receptors. It does not enter the CNS and does not cause drowsiness. (Choice D) Ranitidine is a H2 receptor antagonist that inhibits gastric acid secretion. It has a slight affinity to the CYP450 enzyme, but studies have shown that ranitidine does not have clinically significant interactions with diazepam. (Choice E) Lansoprazole is a proton pump inhibitor that decreases gastric acid secretion. Although both diazepam and lansoprazole are metabolized by the P450 system, studies have shown that lansoprazole does not have clinically significant interactions with diazepam. Educational objective: First generation H1-histamine receptor antagonists, including diphenhydramine and chlorpheniramine, can cause significant sedation, especially when used with other medications that cause CNS depression (such as benzodiazepines). __________ References: Influence of lansoprazole treatment on diazepam plasma concentrations (http://www.ncbi.nlm.nih.gov/pubmed/1424419) Ranitidine does not impair oxidative or conjugative metabolism: noninteraction with antipyrine, diazepam, and lorazepam (http://www.ncbi.nlm.nih.gov/pubmed/6319067)

A 65-Year-Old Male Is Undergoing Rehabilitation After a Stroke