Psychopharmacology Insights: Clozapine and Constipation
Sep 29, 2023
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Psychopharmacology expert, Jonathan Meyer, M.D., talks about the severe side effect of clozapine: constipation. He discusses the cause of constipation due to the drug's strong anticholinergic effects and effective management strategies such as using laxatives and tapering certain medications. The podcast also highlights the importance of managing treatment-resistant illness and provides insights on secretagogues for constipation in clozapine users.
Clozapine can cause severe constipation due to its anticholinergic effects, and managing constipation effectively is crucial to prevent serious medical complications.
To manage constipation caused by clozapine, it is important to gradually discontinue other systemically-acting anticholinergic medications, taper off non-psychiatric anticholinergic medications, temporarily stop supplemental iron, encourage reporting lack of bowel movement, maintain fluid intake and exercise regularly, and consider appropriate laxatives if needed.
Deep dives
Clozapine-induced constipation: A serious adverse effect
Clozapine can cause severe constipation due to its strong anticholinergic effects. The average colonic transit time (CTT) in adults is 24 hours, but in patients on clozapine, the median CTT increases to 110 hours. Common laxatives like docusate only reduce CTT to 62 hours. It is crucial to manage constipation effectively as it can lead to serious medical complications, including ileus which can be fatal.
Strategies for managing clozapine-induced constipation
To manage constipation caused by clozapine, it is important to minimize the use of other systemically-acting anticholinergic medications. Strongly anticholinergic psychotropics and anti-parkinsonian agents should be gradually discontinued when initiating clozapine therapy. Non-psychiatric anticholinergic medications should also be tapered off. Additionally, supplemental iron should be temporarily stopped during clozapine treatment. Patients should be encouraged to report any lack of bowel movement for more than 48 hours, maintain adequate fluid intake, and engage in regular exercise.
Treatment approaches for clozapine-induced constipation
When managing constipation in patients on clozapine, bulk-forming laxatives containing psyllium should be avoided due to slow motility. The initial step involves starting the patient on docusate. If constipation persists, an osmotic laxative like PEG3350 or lactulose can be added. If needed, a stimulant laxative such as senna or bisacodyl can be introduced. In cases where these combinations are ineffective, newer secretagogues like lubiprostone, lenacletide, lenactolotide, or prucalopride can be considered. Severe abdominal pain or feculent vomiting are considered emergencies and require immediate medical attention.
In this episode, we explore a common yet severe side effect of clozapine: Constipation. Why does this drug cause such drastic changes in colonic transit times, and how can we manage it effectively?
Faculty: Jonathan Meyer, M.D. Host: Richard Seeber, M.D.