Other safety alerts
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| The United States: FDA strengthens warning that untreated constipation caused by schizophrenia medicine clozapine (Clozaril) can lead to serious bowel problems |
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The US Food and Drug Administration (FDA) announces that it is strengthening an existing warning that constipation caused by the schizophrenia medicine clozapine (Clozaril, Fazaclo ODT, Versacloz, generics) can, uncommonly, progress to serious bowel complications. This can lead to hospitalization or even death if constipation is not diagnosed and treated quickly. Constipation is a frequent and known side effect of clozapine, but serious and fatal events continue to be reported.
Clozapine affects how the intestines (bowels) function in the majority of patients. It produces effects ranging from constipation (trouble having a bowel movement), which is a common occurrence, to serious but uncommon bowel problems, including complete blockage of the bowels. FDA found that because of the way clozapine works this risk is greater with clozapine than with the other schizophrenia medicines in its drug class. The risk is further increased at higher doses of clozapine and when it is co-prescribed with a type of medicine called anticholinergics, which can slow the movement in the intestines, and other medicines that cause constipation, including opioids. Many different kinds of medicines have these anticholinergic effects.
FDA is requiring a new warning and updates about this risk to be added to the prescribing information of all clozapine products. As part of FDA’s routine monitoring, FDA will continue to monitor clozapine and will report updated information to the public if it becomes available.
Patients may not feel or be aware of constipation symptoms. However, they should contact their health care professional if their bowel movements are less frequent than normal for them, especially if they do not have a bowel movement at least three times a week, they have hard or dry stools, or they have difficulty passing gas. They should contact their health care professional right away if they have symptoms that can be associated with serious bowel problems such as nausea and vomiting, bloating or belly swelling, or belly pain. They should not stop taking their clozapine medicine without first talking with their health care professional, as stopping treatment can cause their schizophrenia symptoms to return or worsen.
Health care professionals should evaluate bowel function before starting a patient on clozapine and avoid co-prescribing clozapine with other anticholinergic medicines that can cause gastrointestinal hypomotility. Advise patients frequently of the significant risk of constipation and life-threatening bowel issues and the need to stay hydrated to prevent constipation. Question patients about the frequency and quality of their bowel movements throughout treatment. Advise patients to contact a health care professional right away if they have difficulty having a bowel movement or passing stools, do not have a bowel movement at least three times a week or less than their normal frequency, or are unable to pass gas. Monitor patients for symptoms of potential complications associated with gastrointestinal hypomotility such as nausea, abdominal distension or pain, and vomiting. Consider prophylactic laxative treatment when starting clozapine in patients with a history of constipation or bowel obstruction.
FDA reviewed the period from 2006 to 2016 and identified 10 cases describing constipation that progressed to serious bowel problems resulting in hospitalization, surgery, or death. These included death of the colon wall (necrotizing colitis), blockage of blood flow to the intestines (intestinal ischemia), death of part of the intestine (intestinal necrosis), and abdominal distention leading to bowel obstruction (volvulus). This number includes only cases submitted to FDA or those found in the medical literature, so there may be additional cases about which it is unaware.
Please refer to the following website in FDA for details:
http://www.fda.gov/drugs/drug-safety-and-availability/fda-strengthens-warning-untreated-constipation-caused-schizophrenia-medicine-clozapine-clozaril-can
In Hong Kong, there are 7 registered pharmaceutical products containing clozapine. All products are prescription-only medicines. So far, the Department of Health (DH) has received 3 cases of adverse drug reaction related to clozapine, but these cases are not related to constipation that progressed to serious bowel complications. Related news was previously issued by Taiwan Food and Drug Administration and the United Kingdom Medicines and Healthcare products Regulatory Agency, and was posted on the Drug Office website on 5 Aug 2015 and 27 Oct 2017. In Dec 2016, the Registration Committee of the Pharmacy and Poisons Board discussed the matter, and decided that the sales pack labels and/or package inserts of clozapine-containing products should include the relevant safety warning. DH will remain vigilant on safety update of the drug issued by other overseas drug regulatory authorities.
Ends/Wednesday, Jan 29, 2020
Issued at HKT 16:00
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