Guidelines for the Use of Antiretroviral Agents in Pediatric HIV Infection
Nucleoside and Nucleotide Analogue Reverse Transcriptase Inhibitors (NRTIs)
Last Updated: March 1, 2016; Last Reviewed: March 1, 2016
|Didanosine (ddI, Videx)
For additional information see Drugs@FDA: http://www.accessdata.fda.gov/scripts/cder/drugsatfda/
Videx Pediatric Powder for Oral Solution: Reconstituted 10 mg/mL
Videx Enteric-Coated (EC) Delayed-Release Capsules (EC Beadlets): 125 mg, 200 mg, 250 mg, and 400 mg
Generic Didanosine Delayed-Release Capsules: 125 mg, 200 mg, 250 mg, and 400 mg
Tablets for Oral Suspension: 100 mg, 150 mg, and 200 mg
|Dosing Recommendations||Selected Adverse Events|
Neonatal/Infant Dose (Aged 2 Weeks to <3 Months):
Pediatric/Adolescent Dose of Didanosine when Combined with Tenofovir Disoproxil Fumarate (TDF):
Drug Interactions (see also the Guidelines for the Use of Antiretroviral Agents in HIV-1-Infected Adults and Adolescents and http://www.hiv-druginteractions.org/)
- Absorption: The presence of antacids in didanosine oral solution and tablets for oral suspension has the potential to decrease the absorption of a number of medications if given at the same time. Many of these interactions can be avoided by timing doses to avoid giving other medications concurrently with didanosine oral solution.
- Mechanism unknown: Didanosine serum concentrations are increased when didanosine is co-administered with tenofovir disoproxil fumarate (TDF) and this combination should be avoided if possible.
- Renal elimination: Drugs that decrease renal function can decrease didanosine clearance.
- Enhanced toxicity: Didanosine mitochondrial toxicity is enhanced by ribavirin.
- Overlapping toxicities: The combination of stavudine with didanosine may result in enhanced toxicity. That combination should not generally be used (see below).
- More common: Diarrhea, abdominal pain, nausea, and vomiting.
- Less common (more severe): Peripheral neuropathy, electrolyte abnormalities, and hyperuricemia. Lactic acidosis and hepatomegaly with steatosis, including fatal cases, have been reported, and are more common with didanosine in combination with stavudine. Pancreatitis (less common in children than in adults, more common when didanosine is used in combination with TDF or stavudine) can occur. Increased liver enzymes and retinal depigmentation and optic neuritis have been reported. Fall in CD4 T lymphocyte count is reported with use of didanosine with TDF.
- Rare: Non-cirrhotic portal hypertension, presenting clinically with hematemesis, esophageal varices, ascites, and splenomegaly, and associated with increased transaminases, increased alkaline phosphatase, and thrombocytopenia, has been associated with long-term didanosine use.
The International Antiviral Society-USA (IAS-USA) maintains a list of updated resistance mutations (see http://iasusa.org/sites/default/files/tam/october_november_2015.pdf#page=10) and the Stanford University HIV Drug Resistance Database offers a discussion of each mutation (see http://hivdb.standford.edu/DR/).
Didanosine is Food and Drug Administration (FDA)-approved for use in children as part of combination antiretroviral therapy.
Standard Dose in Children Aged >8 months
The standard dose of didanosine oral solution in children aged >8 months is 120 mg/m2 body surface area twice daily.1,2 Doses higher than 180 mg/m2 body surface area twice daily are associated with increased toxicity.3
Special Considerations in Ages 2 Weeks to <8 Months
For infants aged 2 weeks to 8 months, the FDA recommends 100 mg/m2 body surface area per dose twice daily. However, because pharmacokinetic (PK) differences in younger infants (aged 2 weeks–3 months) compared with older children raise concern for increased toxicity in this younger age group, the Panel recommends a dose of 50 mg/m2 of body surface area twice daily for infants aged 2 weeks to 3 months, with an increase to 100 mg/m2/dose twice daily at 3 months, and finally increasing to 120 mg/m2 body surface area per dose twice daily at age 8 months (as above).
Frequency of Administration (Once-Daily or Twice-Daily)
A once-daily dosing regimen may be preferable to promote adherence, and multiple studies support the favorable PKs and efficacy of once-daily dosing of 240 mg/m2 body surface area.4
Although the prescribing information recommends taking didanosine on an empty stomach, this is impractical for infants who must be fed frequently and it may decrease medication adherence by increasing regimen complexity. A comparison showed that systemic exposure measured by area under the curve was similar whether didanosine oral solution was given to children with or without food; absorption of didanosine administered with food was slower and elimination more prolonged.5 To improve adherence, some practitioners administer didanosine without regard to timing of meals. Studies in adults suggest that didanosine can be given without regard to food.6,7 A European study dosed didanosine oral solution as part of a 4-drug regimen either 1 hour before or 1 hour after meals, but allowed the extended-release formulation to be given without food restriction and showed good virologic outcome with up to 96 weeks of follow-up.8
- Fletcher CV, Brundage RC, Remmel RP, et al. Pharmacologic characteristics of indinavir, didanosine, and stavudine in human immunodeficiency virus-infected children receiving combination therapy. Antimicrob Agents Chemother. 2000;44(4):1029-1034. Available at http://www.ncbi.nlm.nih.gov/pubmed/10722507.
- Nacro B, Zoure E, Hien H, et al. Pharmacology and immuno-virologic efficacy of once-a-day HAART in African HIV-infected children: ANRS 12103 phase II trial. Bull World Health Organ. 2011;89(6):451-458. Available at http://www.ncbi.nlm.nih.gov/pubmed/21673861.
- Butler KM, Husson RN, Balis FM, et al. Dideoxyinosine in children with symptomatic human immunodeficiency virus infection. N Engl J Med. 1991;324(3):137-144. Available at http://www.ncbi.nlm.nih.gov/pubmed/1670591.
- King JR, Nachman S, Yogev R, et al. Single-dose pharmacokinetics of enteric-coated didanosine in HIV-infected children. Antivir Ther. 2002;7(4):267-270. Available at http://www.ncbi.nlm.nih.gov/pubmed/12553481.
- Stevens RC, Rodman JH, Yong FH, Carey V, Knupp CA, Frenkel LM. Effect of food and pharmacokinetic variability on didanosine systemic exposure in HIV-infected children. Pediatric AIDS Clinical Trials Group Protocol 144 Study Team. AIDS Res Hum Retroviruses. 2000;16(5):415-421. Available at http://www.ncbi.nlm.nih.gov/pubmed/10772527.
- Sanchez-Conde M, Palacios R, Sanz J, et al. Efficacy and safety of a once daily regimen with efavirenz, lamivudine, and didanosine, with and without food, as initial therapy for HIV Infection: the ELADI study. AIDS Res Hum Retroviruses. 2007;23(10):1237-1241. Available at http://www.ncbi.nlm.nih.gov/pubmed/17961110.
- Hernandez-Novoa B, Antela A, Gutierrez C, et al. Effect of food on the antiviral activity of didanosine enteric-coated capsules: a pilot comparative study. HIV Med. 2008;9(4):187-191. Available at http://www.ncbi.nlm.nih.gov/pubmed/18298579.
- Scherpbier HJ, Bekker V, Pajkrt D, Jurriaans S, Lange JM, Kuijpers TW. Once-daily highly active antiretroviral therapy for HIV-infected children: safety and efficacy of an efavirenz-containing regimen. Pediatrics. 2007;119(3):e705-715. Available at http://www.ncbi.nlm.nih.gov/pubmed/17308244.