DIDANOSINE (DDI)
(di-dan'o-sine)
Videx, Videx EC
Classifications: antiinfective; antiretroviral agent; nucleoside reverse transcriptase inhibitor
Prototype: Lamivudine
Pregnancy Category: B
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25 mg, 50 mg, 100 mg, 150 mg, 200 mg tablets; 125 mg, 200 mg, 250 mg, 400 mg delayed release capsules; 100 mg, 167 mg, 250 mg, 2 g, 4 g powder for oral solution
DDI interferes with the HIV RNA-dependent DNA polymerase (reverse transcriptase), thus preventing replication of the virus.
Synthetic purine nucleotide that inhibits replication of HIV.
Advanced HIV infection in patients who are intolerant to zidovudine (AZT) or who demonstrate significant clinical or immunological
deterioration during zidovudine therapy.
Hypersensitivity to any of the components in the formulation, pregnancy (category B), lactation.
Individuals with peripheral vascular disease, history of neuropathy, chronic pancreatitis, renal impairment, or any liver
impairment.
HIV Infection
Adult: PO <60 kg, tablets, 250 mg q.d. or 125 mg b.i.d. (take 2 tablets at each dose to ensure adequate buffering); <60 kg, powder, 167 mg b.i.d.;  60 kg, tablets, 400 mg q.d. or 200 mg b.i.d.; 60 kg, powder, 250 mg b.i.d.
Child: PO 120 mg/m2 b.i.d., <1 y, give a 1-tablet dose; >1 y, give a 2-tablet dose
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Oral
- Give drug on an empty stomach. Food should not be consumed within 15–30 min of drug administration.
- Give with water. Do NOT give with fruit juice or any other acid-containing liquid.
- Chewable tablets must be thoroughly chewed or crushed and dispersed in at least 30 mL (1 oz) of water and immediately swallowed.
- Mix powder for oral solution (buffered) with at least 120 mL (4 oz) of water, stir until dissolved (requires 2–3 min),
and immediately swallowed.
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Note: Powder for oral solution (pediatric) is prepared by pharmacist to yield a concentration of 10 mg/mL. Shake solution thoroughly
before administration.
- Dosage reduction may be indicated in those with renal or hepatic impairment.
- Store reconstituted liquid in a tightly closed container in refrigerator for up to 30 d.
CV: Palpitations, thrombophlebitis, arrhythmias, vasodilation. CNS:
Headache, dizziness, nervousness, insomnia, peripheral neuropathy, lethargy, poor coordination, seizures. Special Senses: Retinal depigmentation, photophobia, blurred vision, optic neuritis, diplopia, blindness. GI:
Abdominal pain, nausea, vomiting, diarrhea, constipation, stomatitis, dry mouth, pancreatitis, increased liver enzymes. Hematologic: Increased WBC, neutrophil, lymphocyte, and platelet counts; increased Hgb, thrombocytopenia, ecchymosis, hemorrhage, petechiae. Metabolic: Hypocalcemia, hypokalemia, hypomagnesemia, hyperuricemia (asymptomatic), hypertriglyceridemia. Musculoskeletal: Muscle atrophy, myalgia, arthritis, decreased strength. Respiratory:
Asthma, cough, dyspnea, epistaxis, rhinitis, rhinorrhea, hypoventilation, pharyngitis, rhonchi or rales, sinusitis, congestion. Skin: Rash, impetigo, eczema, pruritus, sweating, erythema.
Drug:
aluminum- and magnesium-containing antacids may increase the aluminum- and magnesium-associated adverse effects of tablets. The effectiveness of dapsone in prophylaxis of Pneumocystis carinii pneumonia may be reduced by concomitant didanosine. May cause additive neuropathy with zalcitabine (ddC). Food: Absorption is significantly decreased by food. Take on an empty stomach.
Absorption: Rapidly absorbed from GI tract when administered to fasting patient with antacids; 23–40% reaches systemic circulation. Peak: 0.6–1 h. Distribution: Distributed primarily to body water; 21% reaches CSF; crosses placenta. Elimination: 36% excreted in urine. Half-Life: 0.8–1.5 h.
Assessment & Drug Effects
- Monitor for S&S of pancreatitis (e.g., abdominal pain, nausea, vomiting, elevated serum amylase). Report immediately to physician
and withhold drug until ruled out.
- Monitor for S&S of peripheral neuropathy (e.g., numbness, tingling, burning, pain in hands or feet). Report to physician;
dose reduction may be indicated.
- Monitor patients with renal impairment for drug toxicity and hypermagnesemia manifested by muscle weakness and confusion.
Patient & Family Education
- Report immediately to physician any of the following: Abdominal pain, nausea, or vomiting.
- Do not breast feed while taking this drug.
Canadian drug name; 
Prototype drug