https://interactions.guidetherapeutiquevih.com/en/interaction-details?id=15601

Atazanavir / cobicistat

Sildenafil (Viagra)

Modification of dose and/or administration time necessary.

No pharmaceutical opinion available for this interaction.

Mechanism

Atazanavir / cobicistat can inhibit the metabolism (CYP 3A4) and increase the plasma concentration of Sildenafil (Viagra).

Atazanavir / cobicistat

Pharmacodynamic effects

–

Recommendations

–

Alternative solution(s)

–

Sildenafil (Viagra)

Pharmacodynamic effects

Possible increase of adverse effects.

Recommendations

Start at the lowest possible dose (12.5 mg) and increase up to a maximum of 25 mg per 48 hours according to response and adverse effects.

If already used, reduce the dose to a maximum of 25 mg per 48 hours.

Monitor closely clinical efficacy and appearance of adverse effects.

In patients already being treated with this combination and tolerating it, if deemed appropriate, keep actual treatment and exercise close monitoring of adverse effects.

Give extra caution to patients with hepatic or renal insufficiency, or older than 65 years.

Alternative solution(s)

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Monitor

Sildenafil toxicity: hypotension, tachycardia, headache, dizziness, flushing, visual changes (difficulty distinguishing blue and green) and syncope.

Tests

–

Pharmacokinetic parameters

–

Comment

Caution: Liver impairment (Child Pugh A and B): increases AUC to 84% and kidney failure (Clcr < 30 ml/min): increases AUC to 100% and age > 65 years old can also increase the concentrations of sildenafil.

Contraindicated with sildenafil (Revatio). See sildenafil (Revatio).

Reference
  • 3230
    Atazanavir/cobicistat (Evotaz), Bristol-Myers Squibb, Québec, Canada, 8 septembre 2017.
  • 244
    Sildénafil (Viagra), Pfizer, Québec, Canada, 26 mai 2015.
  • 2375
    Sildenafil (Revatio), Pfizer, Quebec, Canada, 30 oct 2017.