Search
didanosine; dideoxyinosine (Videx, ddI)
Tradename: Videx.
Indications: treatment of HIV infection
Dosage: (administration)
1) take on an empty stomach
2) tablets should be thoroughly chewed, manually crushed or dispersed in at least 1 oz of water
3) adult > 60 kg: 200 mg PO BID
4) adult < 60 kg: 125 mg PO BID
Videx EC (enteric coated), swallowed whole, not chewed
Tabs: 25, 50, 100, 150 mg.
Powder: 100, 167, 250, 375 mg.
Dosage adjustment in renal failure:
creatinine clearance dosage
> 50-90 mL/min 12 hour dosing
10-50 mL/min 24 hour dosing
< 10 mL/min* 50% of dose every 24 hours
* dose after hemodialysis
Pharmacokinetics:
1) degraded at acidic pH (food reduces absorption by 50%)
2) elimination 1/2life is 1.6 hours (4.5 hours ESRD)
3) 50% renally cleared
4) patients with creatinine clearance < 60 mL/min may be at greater risk of toxicity
Adverse effects:
1) common (> 10%)
- peripheral neuropathy
- dose-dependent
- painful
- predominantly distal, symmetric sensory polyneuropathy
- pancreatitis
- headache
- anxiety
- irritability
- insomnia
- restlessness
- abdominal pain
- nausea
- diarrhea
2) uncommon (< 1%)
- anemia, granulocytopenia, leukopenia, thrombocytopenia, hepatitis, hypersensitivity, retinal depigmentation, seizures
3) other [2]
- rash
- chills
- syndrome of hepatic steatosis & lactic acidosis [5]
- increased risk of heart attack [7]
- non-cirrhotic portal hypertension [8]
Drug interactions:
1) increased risk of pancreatitis in combination with:
a) alcohol
b) ganciclovir
2) separate administration of ddI by at least 2 hours from:
a) fluoroquinolones
b) tetracyclines
c) H2 blockers
d) dapsone
e) ketoconazole (inactivated by ddI)
3) zalcitabine (ddC) SHOULD NOT BE USED in combination; increased risk of neurotoxicity
Laboratory:
- didanosine in serum/plasma
Mechanism of action:
1) synthetic purine nucleoside analog of deoxyadenosine
2) converted to 5'triphosphate (active anti-viral metabolite) by cellular enzymes
3) inhibits replication of HIV by competitively inhibiting HIV reverse transcriptase
Interactions
drug interactions
drug adverse effects of antiretroviral agents
General
nucleoside reverse transcriptase inhibitor (NRTI)
Properties
MISC-INFO: elimination route LIVER
KIDNEY
pregnancy-category B
safety in lactation -
Database Correlations
PUBCHEM correlations
References
- The Pharmacological Basis of Therapeutics, 9th ed.
Gilman et al, eds. Permagon Press/McGraw Hill, 1996
- Drug Information & Medication Formulary, Veterans Affairs,
Central California Health Care System, 1st ed., Ravnan et al
eds, 1998
- Medical Knowledge Self Assessment Program (MKSAP) 11, American
College of Physicians, Philadelphia 1998
- Kaiser Permanente Northern California Regional Drug
Formulary, 1998
- Journal Watch 20(17):137, 2000
Miller et al Ann Intern Med 133:192, 2000
- Sanford Guide to antimicrobial therapy 2001
- FDA MedWatch (link for both abacavir & didanosine)
http://www.fda.gov/medwatch/safety/2008/safety08.htm#abacavir
- FDA MedWatch
Videx/Videx EC (didanosine): Labeling Revision - Risk of Non-Cirrhotic Portal Hypertension
http://www.fda.gov/Safety/MedWatch/SafetyInformation/SafetyAlertsforHumanMedicalProducts/ucm199343.htm