Hovilpri

Hovilpri is used to treat lesions caused by herpes simplex virus (HSV) infection that have not improved with the medicines acyclovir, valacyclovir, or famciclovir, in adults with weakened immune systems (immunocompromised). Hovilpri does not cure HSV infection.

Hovilpri (pritelivir) is an antiviral that inhibits the herpes simplex virus (HSV) helicase-primase complex, an enzyme complex the virus needs to unwind and copy its DNA. By blocking this complex, pritelivir prevents new viral DNA synthesis in both HSV-1 and HSV-2. Because it works differently from acyclovir and foscarnet, it remains active against HSV strains resistant to nucleoside analogs or foscarnet, and cross-resistance is unlikely. Hovilpri belongs to the drug class called helicase-primase inhibitors.

Herpes simplex virus has two types: HSV-1, which mainly causes cold sores (labial herpes) but is increasingly a cause of genital herpes, and HSV-2, which causes most cases of genital herpes. Both cause recurring, painful sores. In severe cases, they can lead to complications including encephalitis, meningitis, disseminated disease, keratitis, and neonatal herpes.

Hovilpri (pritelivir) received FDA approval on October 10, 2026.

• Take Hovilpri exactly as your healthcare provider tells you to take it.
• The usual dose of Hovilpri is: On Day 1 (first day of treatment): take 400 mg by mouth (four 100 mg tablets) at one time. After Day 1: take 100 mg by mouth (one 100 mg tablet) 1 time a day.
• Take Hovilpri with or without food.
• Take Hovilpri as prescribed by your healthcare provider until your HSV lesions have healed.
• If you take medicines that reduce stomach acid: If you take an H2-receptor blocker (such as famotidine, ranitidine), take Hovilpri at least 2 hours before or 12 hours after taking the H2-receptor blocker. If you take an antacid (such as Tums, Mylanta, Maalox), take Hovilpri 2 hours before or 2 hours after taking the antacid.
• If you miss a dose of Hovilpri, take it as soon as you remember. If you don't remember until the next day's scheduled dose, take 2 tablets at that time.
• If you take too much Hovilpri, call your healthcare provider or the Poison Help line (1-800-222-1222), or go to the nearest hospital emergency room right away.

Avoid taking the following proton pump inhibitor medicines during treatment with Hovilpri:

• esomeprazole or rabeprazole
• omeprazole or lansoprazole (daily dose above 20 mg)
• pantoprazole (daily dose above 40 mg).

Talk to your healthcare provider before taking any of these medicines.

Hovilpri may affect the way other medicines work, and other medicines may affect the way Hovilpri works. Tell your healthcare provider about all the medicines you take. Especially tell your healthcare provider if you take medicines used to lower stomach acid, including:

• proton pump inhibitors (PPIs) (such as esomeprazole, rabeprazole, omeprazole, lansoprazole, or pantoprazole).
• H2-receptor blockers (such as famotidine, ranitidine).
• antacids (medicines such as Tums, Mylanta, Maalox).

See "How should I take Hovilpri?" and "What should I avoid while taking Hovilpri?" if you take any of these medicines.

Know the medicines you take. Keep a list of them to show your healthcare provider and pharmacist when you get a new medicine.

Before taking Hovilpri, tell your healthcare provider about all of your medical conditions, including if you:

• are pregnant or plan to become pregnant. It is not known if Hovilpri will harm your unborn baby.
• are breastfeeding or plan to breastfeed. It is not known if Hovilpri passes into your breast milk. Talk with your healthcare provider about the best way to feed your baby if you take Hovilpri.

Tell your healthcare provider about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements.

It is not known if Hovilpri is safe and effective in children less than 18 years of age.

The most common side effect of Hovilpri is headache.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088 or Asahi Kasei Therapeutics, Inc. at 1-844-835-6947.

Hovilpri was evaluated in PRIOH-1, a randomized, open-label trial in 101 immunocompromised adults with mucocutaneous HSV infection refractory to acyclovir, valacyclovir, or famciclovir. Participants received Hovilpri or investigator’s choice treatment (mostly IV foscarnet) for up to 28 days, extended to 42 days if lesions were improving.

• All lesions healed by Day 28: 63% with Hovilpri vs 34% with investigator’s choice (p=0.0047).
• All lesions healed by Day 42: 82% vs 42%.
• In a separate single-arm part of the trial, lesions healed by Day 28 in 40% of 35 participants with acyclovir/foscarnet-refractory infection or foscarnet intolerance, and by Day 42 in 66%.

Store Hovilpri tablets between 68°F and 77°F (20°C to 25°C).

Keep Hovilpri and all medicines out of the reach of children.

Active ingredient: pritelivir mesylate

Inactive ingredients: colloidal silicon dioxide, croscarmellose sodium, magnesium stearate, mannitol, and microcrystalline cellulose. The film-coat contains hydroxypropyl methylcellulose, polyethylene glycol, and calcium diphosphate.

Hovilpri is distributed by Asahi Kasei Therapeutics, Inc., Cary, North Carolina 27518.

Hovilpri is a registered trademark of Asahi Kasei Therapeutics, Inc. or its subsidiary.

For more information, go to www.HOVILPRI.com or call 1-844-835-6947.