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Sephira Med Centres

Scan · vardenafil

What do strong CYP3A4 inhibitors do to Levitra?

Medically reviewed by Dr. Yuki Tanaka, MD - Clinical pharmacology, Toronto

Last reviewed · 3 min read · Updated

Bone review card, cobalt edge, lime chip: tiny 2.5 under a ceiling

They raise exposure. Ritonavir 600 mg twice daily with vardenafil 5 mg raised AUC 49-fold and Cmax 13-fold and stretched half-life to about 26 hours. The cap is a single 2.5 mg tablet in a 72-hour period. Cobicistat uses the same 72-hour 2.5 mg cap. Indinavir, saquinavir, atazanavir, ketoconazole 400 mg, itraconazole 400 mg, and clarithromycin cap 2.5 mg in 24 hours. Ketoconazole 200 mg, itraconazole 200 mg, and erythromycin cap 5 mg in 24 hours. Those 2.5 mg tablets exist for this math.

Why 2.5 exists on this ladder

The 2.5 mg film-coated tablet is the inhibitor floor. It is not a joke dose and not a QT bargain.

Strength inventory sits on the four-tablet scan. Usual uninhibited start remains 10 mg.

The 24-hour 2.5 mg list

Indinavir, saquinavir, atazanavir, ketoconazole 400 mg daily, itraconazole 400 mg daily, and clarithromycin cap a single 2.5 mg swallow in 24 hours.

Indinavir 800 mg three times daily with vardenafil 10 mg had raised AUC 16-fold and Cmax 7-fold and doubled half-life. That is why the cap collapsed.

The 72-hour 2.5 mg cap

A single 2.5 mg vardenafil dose must not be exceeded in a 72-hour period with ritonavir. Cobicistat uses the same cap.

Once daily would be too often on those boosters.

What does ritonavir do to exposure?

Ritonavir 600 mg twice daily with vardenafil 5 mg produced a 49-fold AUC rise and a 13-fold Cmax rise. Half-life went to about 26 hours.

That is the ugliest labelled interaction. Do not freelance a 10 mg start on that pair.

The 5 mg in 24 hours list

Ketoconazole 200 mg daily, itraconazole 200 mg daily, and erythromycin cap a single 5 mg swallow in 24 hours.

Ketoconazole 200 mg daily with vardenafil 5 mg had raised AUC 10-fold and Cmax 4-fold. The 5 mg cap is not a usual adult start.

Erythromycin 500 mg three times daily with vardenafil 5 mg produced a 4-fold AUC rise and a 3-fold Cmax rise. Same 5 mg in 24 hours cap.

Cobicistat matches the long cap

Cobicistat is listed with ritonavir: no more than 2.5 mg in a 72-hour period.

A modern booster milligram does not open a 10 mg Levitra. Ask the clinician who owns the antiviral.

Sources

  1. DailyMed vardenafil hydrochloride tablets, setid d2dce236-257e-44b6-93a9-9f0280257c6a

Checked against the current label and reviewed by Dr. Yuki Tanaka. See Scan, Tag, Board-check, Post.

Board thread

Answers follow the U.S. Levitra label.

Lois Q., Humber Bay Grapefruit with 10 mg. Same as ritonavir?

Board reply

Grapefruit juice is named as likely to raise exposure. It is not the 49-fold ritonavir sitting. Do not treat juice as a licensed booster, and do not ignore it as water.

Ava D., Yorkville Ritonavir plus 10 mg vardenafil from a weekend clinic. Keep it?

Board reply

Do not take it. The labelled cap on ritonavir is 2.5 mg once in 72 hours. Call the clinic and the prescriber who owns the ritonavir. Forty-nine-fold AUC is not a rounding error.

Hector V., Downsview Nail course of ketoconazole 200 mg. What Levitra is left?

Board reply

A single 5 mg swallow in 24 hours is the labelled cap on ketoconazole 200 mg daily. Confirm the course is still running before anyone writes 10 mg.