SAFETY UPDATE: Ritonavir or Cobicistat and potent corticosteroid eye drops

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On September 28th, 2018 – Health Canada issued an information update regarding labeling changes in the product monograph for fluorometholone acetate (FlarexTM) eye drops. Systemic corticosteroid adverse reactions such as Cushingoid symptoms or adrenal suppression may occur after intensive or long-term, continuous fluorometholone use in persons treated with CYP3A4 inhibitors including ritonavir (NorvirTM, KaletraTM ) or cobicistat (in PrezcobixTM, StribildTM, GenvoyaTM), which are used as antiretroviral ‘boosters’ in the treatment of HIV.

The product monographs for other potent ophthalmic corticosteroids, including difluprednate (DurezolTM) and dexamethasone (MaxidexTM, MaxitrolTM, TobradexTM) include similar drug interaction warnings with ritonavir and cobicistat.

The combination of potent corticosteroid eye drops with ritonavir or cobicistat should be avoided unless the benefit outweighs the increased risk, in which case patients should be monitored for systemic corticosteroid adverse reactions.

For more information: Click here to view the Health Canada advisory

The drug interaction between ritonavir or cobicistat and other corticosteroid products such as inhalers, nasal sprays, and intra-articular injections is well documented.

For more information about how to manage or monitor the drug interaction between ritonavir or cobicistat and ophthalmic/ inhaled/ injectable corticosteroids, Click here to download the BC-CfE Pharmacovigilance Safety Alert Bulletin (June 2010) on this topic.

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During the Canada Post strike announced September 25, 2025, the following measures will be undertaken to minimize service disruption to BC-CfE clients and providers.

  • The BC-CfE Laboratory has transitioned to private courier for delivery of outgoing reports and documents. Results required urgently can be faxed upon request. (Lab Contact Information: Phone 604-806-8775; FAX 604-806-9463)
  • The BC-CfE Drug Treatment Program (DTP) will fax outgoing forms and documents to the provider’s office. (DTP Contact Information: Phone 604-806-8515; FAX 604-806-9044)
  • St. Paul’s Hospital Ambulatory Pharmacy has transitioned to private courier for delivery of medications. We recommend requesting medication at least 2 weeks in advance in case of delivery delays, particularly to rural/remote parts of BC. (Contact Information: Phone 1-800-547-3622; FAX 604-806-8675)

During the Canada Post strike, we recommend that documents be faxed or couriered to our sites, versus utilization of regular mail service

The BC-CfE Laboratory is streamlining reporting processes for certain tests in order to simplify distribution and record-keeping, and to ensure completeness of results. Beginning September 2, 2025, results for the ‘Resistance Analysis of HIV-1 Protease and Reverse Transcriptase’ (Protease-RT) and ‘HIV-1 Integrase Resistance Genotype’ tests will be combined into a single ‘HIV-1 Resistance Genotype Report’.
For more details and example reports, please click on the button below

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