Case study: Dexamethasone and ritonavir interaction
Background information
A hospital pharmacist submitted a Yellow Card report raising his concerns over the interaction between ritonavir and topical corticosteroids. The report was related to a young male who was on long-term antiretroviral therapy (ART).
He was seen for an acute for keratoconjunctivitis and prescribed dexamethasone eye drops to be taken every two hours. Within a short period, he was completely adrenalised with Cushing’s syndrome. The pharmacist stated that due to few alternative treatments for keratoconjunctivitis, the ART regimen was changed to allow dexamethasone to be continued and the patient recovered. The pharmacist felt warnings about interactions needed to be clearer, particularly for dexamethasone because there aren’t many alternative treatment options for keratoconjunctivitis and therefore HIV medications may need to be changed.
Investigation
The Medicines and Healthcare products Regulatory Agency (MHRA) received notification of an additional UK case of an interaction between dexamethasone and ritonavir reported by a pharmaceutical company. This case also involved topical dexamethasone and described resulting Cushingoid reactions.
Response
A regular review of all available safety information examined these reports. MHRA experts agreed with the pharmacist’s concerns in the Yellow Card report. This interaction was thought to be linked to a protein found mainly in the liver and intestine that break down and removes toxins and medicines from the body. As a result, MHRA took regulatory action to ensure the product information was improved. Information was added about potential side effects, including the interaction between ophthalmic dexamethasone and ritonavir, to highlight that Cushing’s syndrome and/or adrenal suppression may occur after intensive or long-term therapy in patients, including children.
It was advised that treatment should be gradually reduced, not stopped abruptly. MHRA also published a Drug Safety Update article to communicate advice from the product information and raise awareness among healthcare professionals.
Additional information
Corticosteroids are an anti-inflammatory drug used to reduce the symptoms of an overactive immune system often inflammation. Ritonavir is used to control HIV infection in combination with other drugs.
Keratoconjunctivitis is an uncommon condition and can cause soreness, itching and redness of the eyes and
eyelids. AKC and VKC are a bit like eczema affecting the surface membrane of your eye instead of the skin.
Cushingoid/Cushing’s syndrome is a condition caused by having too much of a hormone called cortisol in your body. It can be serious if it's not treated.
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