Tenofovir alafenamide

Oral
Chronic hepatitis B

CrCl (mL/min)	Dosage
<15	Not recommended.

Child-Pugh class B or C: Not recommended.

Hypersensitivity.

Patient with HBV and HIV-1 co-infection. Renal and hepatic impairment. Pregnancy and lactation.

Significant: Acute renal failure and/or Fanconi syndrome.
Gastrointestinal disorders: Diarrheoa, vomiting, nausea, abdominal pain, abdominal distention, flatulence.
General disorders and administration site conditions: Fatigue.
Investigations: Decreased bone mineral density, increased serum alanine aminotransferase.
Musculoskeletal and connective tissue disorders: Arthralgia, back pain.
Nervous system disorders: Dizziness, headache.
Respiratory, thoracic and mediastinal disorders: Cough.
Skin and subcutaneous tissue disorders: Rash, pruritus.
Potentially Fatal: Lactic acidosis, hepatomegaly with steatosis.

PO: Z (Current evidence suggests that tenofovir disoproxil does not increase the risk of pregnancy-related adverse effects. Tenofovir disoproxil is one of the recommended antiviral agents in management of HIV and/or hepatitis B during pregnancy.)

This drug may cause dizziness, if affected, do not drive or operate machinery.

Perform HIV testing prior to initiation of therapy. Monitor urine glucose, urine protein prior to initiation and as clinically indicated; LFT, serum creatinine, serum phosphorus.

Increased plasma concentration with P-gp strong inhibitors (e.g. itraconazole, ketoconazole). Decreased plasma concentration with carbamazepine, phenobarbital, fosphenytoin, phenytoin, tipranavir, ritonavir, rifampin, primidone. May diminish the therapeutic effect of cladribine.

Decreased plasma concentration with St. John’s wort.

Description:
Mechanism of Action: Tenofovir alafenamide is a phosphonamidite prodrug of tenofovir which inhibits hepatitis B virus (HBV) replication through incorporation into the viral DNA by HBV reverse transcriptase resulting to DNA chain termination.
Pharmacokinetics:
Absorption: Rapidly absorbed from the gastrointestinal tract. Time to peak plasma concentration: 0.48 hours.
Distribution: Crosses placenta, enters breast milk. Plasma protein binding: 80%.
Metabolism: Hydrolysed intracellularly into tenofovir then phosphorylated to the active form, tenofovir diphosphate; minimally metabolised by CYP3A4.
Excretion: Via urine (<1%); faeces (31.7%). Elimination half-life: 0.51 hours.

Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 9574768, Tenofovir alafenamide. https://pubchem.ncbi.nlm.nih.gov/compound/Tenofovir-alafenamide. Accessed Feb. 24, 2021.

Store below 30°C.

Antivirals

J05AF13 - tenofovir alafenamide ; Belongs to the class of nucleoside and nucleotide reverse transcriptase inhibitors. Used in the systemic treatment of viral infections.

Anon. Tenofovir Alafenamide. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 04/02/2021.

Buckingham R (ed). Tenofovir. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 04/02/2021.

Joint Formulary Committee. Tenofovir Alafenamide. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 04/02/2021.

Vemlidy Tablet (Gilead Sciences, Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 04/02/2021.