Date of report 21 Dec 2021
Reported case interaction between
Ritonavir and Daclatasvir
Ritonavir and Daclatasvir
Drugs suspected to be involved in the DDI-summary
Complete list of drugs taken by the patient
Metformin 850 mg OD, Sofosbuvir 300mg/Daclatasvir 60mg
Clinical case description
Social Hx:
- Injecting drug user
- Alcoholic
- Heavy smoker
Medical Hx:
- Living with HIV five years ago and on HAART
- Diagnosed with DM type II 2 years ago and on Metformin
Upon follow up after 4 weeks starting Hep C (Tab Sofosbuvir 300mg/Daclatasvir 60mg) :
- Patient complaint easy feel tired and lose of appetite
- Physical examination - jaundice
- Elevated ALT (71 U/L), anaemia (HB = 9 d/L)
- Blood glucose plasma level = 11 mm/mol
Suspect:
- Toxicity of Daclatasvir ( CYP3A4 metabolite) due to inhibition of Ritonavir (CYP3A4 inhibitor) decrease the elimination and remain in the plasma.
- Action is to reduce the Daclatasvir dose from 60mg to 30mg.
Clinical Outcome
Drug Interaction Probability Scale (DIPS)
Editorial Comment
This interaction is highlighted in the Daklinza Prescribing Information ie a PK study is described showing a decrease in exposure of daclatasvir (non dose normalized data) with the recommendation to 'decrease the daclatasvir dose to 30 mg once daily'. This case highlights the importance of the prescriber/health care professional having ready access to the relevant information before starting treatment. This patient should not have been on daclatasvir 60 mg. Note that hepatic impairment (CP-A, CP-B or CP-C) has no effect on daclatasvir exposure unlike the major impact on HCV protease inhibitors. This patient was CP-B.