te-NOE-fo-veer al-a-FEN-a-mide

Therapeutic Classification: antiretrovirals

Pharmacologic Classification: nucleoside reverse transcriptase inhibitors

• Chronic hepatitis B virus (HBV) infection in patients with compensated liver disease.

• Converted by hydrolysis to tenofovir and subsequently phosphorylated to the active metabolite, tenofovir diphosphate, which inhibits replication of HBV through incorporation into viral DNA by the HBV reverse transcriptase resulting in disruption of DNA synthesis.

• Decreased progression/sequelae of chronic HBV infection.

Absorption: Tenofovir alafenamide is a prodrug, which is hydrolyzed into tenofovir; absorption enhanced by high-fat meals.

Distribution: Unknown.

Metabolism/Excretion: Tenofovir is phosphorylated to tenofovir diphosphate (active metabolite); 32% excreted in feces, <1% in urine.

Half-life: 0.51 hr.

(plasma concentrations)

Contraindicated in:

• End-stage renal disease (CCr <15 mL/min) (not receiving hemodialysis)
• Decompensated hepatic impairment.

Use Cautiously in:

• Coinfection with HIV and chronic HBV
• Renal impairment or receiving nephrotoxic medications (↑ risk of renal impairment)
• OB: Use during pregnancy only if potential maternal benefit justifies potential fetal risk
• Lactation: Use while breastfeeding only if potential maternal benefit justifies potential risk to infant
• Pedi: Children <12 yr (safety and effectiveness not established).

GI: ↑amylase, ↑ liver enzymes, abdominal pain, LACTIC ACIDOSIS/HEPATOMEGALY WITH STEATOSIS, nausea.

GU: ACUTE RENAL FAILURE/FANCONI SYNDROME, glycosuria.

Metab: hyperlipidemia.

MS: ↑creatine kinase, back pain.

Neuro: fatigue, headache.

Resp: cough.

Drug-Drug:

• Nephrotoxic agents, including NSAIDs, ↑ risk of nephrotoxicity; avoid concurrent use.
• Medications that compete for active tubular secretion, including acyclovir, cidofovir, ganciclovir, valacyclovir, valganciclovir, or aminoglycosides, may ↑ levels and the risk of toxicity; avoid concurrent use.
• Carbamazepine, oxcarbazepine, phenobarbital, phenytoin, rifabutin, rifampin, or rifapentine may ↓ levels and its effectiveness; concurrent use with oxcarbazepine, phenobarbital, phenytoin, rifabutin, rifampin, or rifapentine not recommended; ↑ tenofovir alafenamide dose to 50 mg once daily when used with carbamazepine.

Drug-Natural Products:

• St. John's wort may ↓ levels and its effectiveness; concurrent use not recommended.

• PO (Adults and Children 12 yr): 25 mg once daily.

• Tablets: 25 mg;
• In combination with: bictegravir and emtricitabine (Biktarvy); darunavir, cobicistat, and emtricitabine (Symtuza); elvitegravir, cobicistat, and emtricitabine (Genvoya); emtricitabine (Descovy); emtricitabine and rilpivirine (Odefsey). See Appendix [not included in this PDA edition].

• Monitor signs of hepatitis (jaundice, fatigue, anorexia, pruritus) during therapy. Upon discontinuation of therapy, monitor for exacerbations of HBV for at least several mo after stopping therapy.

• Test patient for HIV-1 infection before starting therapy; Vemlidy should not be used alone in patient with HIV-1 infection.
  • Monitor liver function tests and HBV levels during and following therapy. If therapy is discontinued, may cause severe exacerbation of HBV. Lactic acidosis may occur with hepatic toxicity causing hepatic steatosis; may be fatal, especially in women.
  • May cause renal impairment. Monitor serum creatinine, estimated CCr, urine glucose, and urine protein before starting and periodically during therapy. Also assess serum phosphorous in patients with chronic kidney disease. Discontinue medication in patients who develop clinically significant ↓ in renal function or evidence of Fanconi syndrome.
  • May cause ↑ ALT, AST, serum CK, serum amylase, LDL cholesterol, and glycosuria.

• PO: Administer once daily with food.

• Instruct patient to take medication as directed. Avoid missing doses. Advise patient to read Patient Information before starting and with each Rx refill in case of changes.
• Advise patient to notify health care professional immediately if symptoms of lactic acidosis (feel very weak or tired, have unusual [not normal] muscle pain, have trouble breathing, have stomach pain with nausea or vomiting, feel cold, especially in your arms and legs, feel dizzy or lightheaded, have a fast or irregular heartbeat) or severe liver problems (yellow skin or whites eyes, dark "tea-colored" urine, light-colored bowel stools, loss of appetite, nausea, pain, aching, or tenderness in right side of abdomen) occur.
• Instruct patient to notify health care professional of all Rx or OTC medications, vitamins, or herbal products being taken and consult health care professional before taking any new medications.
• Advise females of reproductive potential to notify health care professional if pregnancy is planned or suspected or if breastfeeding. Advise patient taking oral contraceptives to use a nonhormonal method of birth control during therapy. Inform patient of pregnancy exposure registry that monitors pregnancy outcomes in women exposed to Vemlidy during pregnancy. Register patient in the Antiretroviral Pregnancy Registry by calling 1-800-258-4263.

• Decreased progression/sequelae of chronic HBV infection.

Vemlidy