Didanosine
VIDEX
What it isA dideoxynucleoside reverse transcriptase inhibitor (NRTI) that, after intracellular phosphorylation, terminates HIV proviral DNA chain elongation.
Why this oneAn older, now rarely used HIV agent historically valued as a thymidine-sparing backbone option.
What limits itIt causes dose-related peripheral neuropathy and pancreatitis, requires acid buffering or enteric coating, and its toxicity is amplified by tenofovir, allopurinol, and ribavirin.
FDA label
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| FDA dosing | Population | Start | Target | Max |
|---|---|---|---|---|
| HIV-1 infection (combination antiretroviral therapy) | Adults (weight-based) | >=60 kg: 400 mg QD; 25-<60 kg: 250 mg QD; 20-<25 kg: 200 mg QD | Same (fixed weight-based dose) | 400 mg QD |
| HIV-1 infection (combination antiretroviral therapy) | Peds 6-18 y, >=20 kg, able to swallow capsules | Same weight-based table as adults (200-400 mg QD) | Same | 400 mg QD |
Renal Adults: CrCl 30-59: 200 mg QD (>=60 kg) / 125 mg QD (<60 kg); CrCl 10-29: 125 mg QD; CrCl <10, CAPD or hemodialysis: 125 mg QD (>=60 kg; <60 kg <10 mL/min use pediatric powder); no post-hemodialysis supplement. Peds: consider reduction (insufficient data)
Hepatic No adjustment needed
With tenofovir DF: reduce to 250 mg QD (>=60 kg) or 200 mg QD (<60 kg) taken with tenofovir + light meal or fasted (CrCl >=60 only; not established below)
Instructions
- Take on an empty stomach
- Swallow capsules intact
Contraindications
- Coadministration with allopurinol (increases didanosine exposure/toxicity)
- Coadministration with ribavirin (increased ddATP; fatal hepatic failure, peripheral neuropathy, pancreatitis, lactic acidosis reported)
Cautions
- Pancreatitis — dose-related, may be fatal; higher risk with stavudine, renal impairment without dose adjustment, advanced HIV, elderly
- Lactic acidosis/severe hepatomegaly with steatosis; suspend for symptoms
- Hepatic toxicity; avoid hydroxyurea + didanosine + stavudine (fatal hepatic events)
- Non-cirrhotic portal hypertension (incl. cases needing transplant/fatal) — discontinue if evident
- Peripheral neuropathy
- Retinal changes and optic neuritis
- Immune reconstitution syndrome; fat redistribution
Adverse reactions
- Diarrhea
- Peripheral neuropathy/neurologic symptoms
- Nausea
- Headache
- Rash
- Vomiting
Pregnancy Category B; use only if benefit justifies risk — fatal lactic acidosis reported with didanosine + stavudine in pregnancy (use that combo only if clearly needed); pregnancy registry 1-800-258-4263
Lactation Do not breastfeed (HIV transmission risk + potential infant toxicity; excreted in rat milk)
⚠ BOXED WARNINGS
- Pancreatitis
- Lactic acidosis and severe hepatomegaly with steatosis
Principal riskBoxed warning: fatal and nonfatal pancreatitis, and lactic acidosis with severe hepatomegaly and steatosis.
Classes and tags
Clinical profile
Mechanism of action: Didanosine ballicule
