Dosing & Uses
Dosage Forms & Strengths
capsule, extended release
- 125mg
- 200mg
- 250mg
- 400mg
powder for oral solution
- 2 g
- 4 g
HIV Infection
≤60 kg: Extended-release 250 mg PO qDay; 125 mg PO q12hr
>60 kg: Extended-release 400 mg PO qDay; suspension 200 mg PO q12hr
Dosage Modifications
Coadministration with tenofovir
- >60 kg: Decrease didanosine dose to 250 mg/day
- ≤60 kg: Decrease didanosine dose to 200 mg/day
Renal Impairment
>60 kg
- CrCl >60 mL/min: Normal dose
- CrCl 30-59 mL/min: 200 mg PO qDay (extended release/solution) or divided q12hr (solution only)
- CrCl 10-29 mL/min: 125 mg (extended release) or 150 mg (solution) PO qDay
- CrCl <10 mL/min; PD/HD: 125 mg (extended release) or 100 mg (solution) PO qDay
≤60 kg
- CrCl >60 mL/min: Normal dose
- CrCl 30-59 mL/min: Extended release 125 mg PO qDay; solution 150 mg PO qDay or divided q12hr
- CrCl 10-29 mL/min: 125 mg (extended release) or 100 mg (solution) PO qDay
- CrCl <10 mL/min; PD/HD: Solution only: 75 mg PO qDay
Dosing Consideration
Monitoring
- Amylase q4-8Weeks; CBC with different, aminotransferases, K+, triglycerides q6-12Weeks
- Neurologic evaluation q4Weeks
- Periodic retinal exams
Dosage Forms & Strengths
capsule, extended release
- 125mg
- 200mg
- 250mg
- 400mg
powder for oral solution
- 10mg/mL (reconstituted)
tablet for oral suspension
- 100mg
- 150mg
- 200mg
HIV Infection
Indicated for treatment of HIV infection in combination with other antiretroviral agents
Oral solution
NIH HIV guidelines (March 2016)
Manufacturer prescribing information
- 2 week to 8 months: 100 mg/m² PO q12hr
- >8 months: 120 mg/m² PO q12hr
Capsule
Weight-based dosing (6-18 years)
- Children who can safely swallow enteric-coated beadlets or delayed-release capsules (Videx EC or generic capsules)
- 20 to <25 kg: 200 mg PO qDay
- 25 to <60 kg: 250 mg PO qDay
- ≥60 kg: As adults; 400 mg PO qDay (oral suspension: 200 mg PO q12hr)
Dosing Consideration
Monitoring
- Amylase q4-8Weeks; CBC with different, aminotransferases, K+, triglycerides q6-12Weeks
- Neurologic evaluation q4Weeks
- Periodic retinal exams
Interactions
Interaction Checker
No Results

Contraindicated
Serious - Use Alternative
Significant - Monitor Closely
Minor

Adverse Effects
>10%
Diarrhea (19-28%)
Peripheral neuropathy (17-20%)
Increased amylase (15-17%)
Abdominal pain (7-13%)
1-10%
Increased LFT
Increased uric acid
Pancreatitis (patients >65 years had higher frequency of pancreatitis than younger patients)
Pruritus
Rash
Postmarking Reports
Noncirrhotic portal hypertension
Warnings
Black Box Warnings
Fatal and nonfatal pancreatitis reported; suspend if pancreatitis suspected and discontinue if confirmed
Lactic acidosis and severe hepatomegaly with steatosis (including fatal cases) reported with use of nucleoside analogues alone or in combination
Coadministration with stavudine is contraindicated because of increased risk of serious and/or life-threatening events; suspend treatment if clinical or laboratory findings suggestive of lactic acidosis or pronounced hepatotoxicity occurs
Fatal lactic acidosis reported in pregnant women who have received didanosine and stavudine with other antiretroviral agents. Use the combination with caution in pregnant women
Contraindications
Hypersensitivity
Coadministration with allopurinol (may increase didanosine toxicity)
Coadministration with ribavirin (increases actrive metabolite dideoxyadenosine 5’-triphosphate levels, causing fatal hepatic failure, peripheral neuropathy, pancreatitis, and symptomatic hyperlactatemia/lactic acidosis)
Coadministration with stavudine
Cautions
(All NRTIs): Risk of potentially fatal lactic acidosis & severe hepatomegaly with steatosis when used alone or in combination with other antiretrovirals
Risk of potentially fatal pancreatitis, increases if used in combo with stavudine
Risk of potentially fatal bleeding from esophageal varices in patients with non-cirrhotic portal hypertension
Discontinue if pancreatitis occurs; reduce dose for other ADR's
Risk of immune reconstitution syndrome if used in combination w/ other antiretroviral drugs
Risk of retinal changes and optic neuritis
Rapidly degrades in acidic pH, however, EC is protected from stomach acids
Noncirrhotic portal hypertension reported; discontinue if signs/symptoms occur (eg, elevated liver enzymes, esophageal varices, hematemesis, ascites, splenomegaly)
Coadministration of methadone with Videx pediatric powder may significant decrease didanosine concentrations
Patients treated in combination with stavudine may be at increased risk for pancreatitis, lactic acidosis, and hepatic toxicity; coadministration is contraindicated
Treatment has been associated with loss of subcutaneous fat, which is most evident in the face, limbs, and buttocks; incidence and severity of lipoatrophy are related to cumulative exposure, and is often not reversible when treatment is stopped; patients receiving therapy should be frequently examined and questioned for signs of lipoatrophy, and if feasible, therapy should be switched to an alternative regimen if there is suspicion of lipoatrophy
Pregnancy & Lactation
Pregnancy
To monitor maternal-fetal outcomes of pregnant women exposed to didanosine and other antiretroviral agents, an Antiretroviral Pregnancy Registry has been established; physicians are encouraged to register patients by calling 1-800-258-4263
There are no adequate and well-controlled studies of didanosine in pregnant women; drug should be used during pregnancy only if potential benefit justifies potential risk
Lactation
The Centers for Disease Control and Prevention recommend that HIV-infected mothers not breastfeed infants to avoid risking postnatal transmission of HIV; a study in rats showed that following oral administration, didanosine and/or its metabolites were excreted into the milk of lactating rats; it is not known if didanosine is excreted in human milk; because of both potential for HIV transmission and potential for serious adverse reactions in nursing infants, mothers should be instructed not to breastfeed if they are receiving didanosine
Pregnancy Categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk. C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done. D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk. X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist. NA: Information not available.Pharmacology
Mechanism of Action
Nucleoside Reverse Transcriptase Inhibitor (NRTI)
Inhibits in vitro replication of HIV via chain termination & interference with HIV-RNA dependent DNA polymerase
Pharmacokinetics
Bioavailability: 42% (adults); 25% (children)
Protein Bound: <5%
Metabolism: Liver
Excretion: Urine
Vd: 28 L/m² (children); 1.08 L/kg
Half-life elimination: 0.8 hr (children and adolescents); 1.5 hr (adults)
Administration
Powder for Oral Solution Preparation
Prior to dispensing, the pharmacist must reconstitute dry powder to an initial concentration of 20 mg/mL and immediately mix the resulting solution with antacid to a final concentration of 10 mg/mL
Initial solution (20 mg/mL): Reconstitute the product to 20 mg per mL by adding 100 mL or 200 mL of purified water USP, to the 2 g or 4 g of powder, respectively
Final solution (10 mg/mL): Immediately mix one part of the 20 mg/mL initial solution with one part of any commercially available antacid that contains as active ingredients aluminum hydroxide (400 mg/5 mL), magnesium hydroxide (400 mg/5 mL), and simethicone (40 mg/5 mL) for a final dispensing concentration of 10 mg/mL
Oral Administration
Oral solution dispensed as 10 mg/mL with antacid as diluent
Take on empty stomach, at least 30 minutes before food or 2 hr after food; Cmax and AUC reduced by ~46% and 19% respectively in the presence of food
EC not approved for aged <6 yr and for children who weigh <20 kg and unable to swallow capsule whole
Storage
Reconstituted oral solution (10 mg/mL): Refrigerate for up to 30 days at 36-46°F (2-8°C); discard any unused portion after 30 days
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