Didanosine (ddl)

HOW SUPPLIEDTablets (buffered, chewable): 25 mg, 50 mg, 100 mg, 150 mgPowder for oral solution (buffered): 100 mg/packet, 167 mg/packet, 250 mg/ packet,Powder for oral solution (pediatric): 4-oz, 8-oz glass bottles containing 2 g and 4 g of Videx, respectivelyACTIONInhibits the enzyme HIV-RNA-dependent DNA polymerase (reverse transcriptase) and terminates DNA chain growth.INDICATIONS & DOSAGEHIV inftion when antiretroviral thera­py is warranted -Adults weighing 60 kg (1321b) and over: 200 mg (tablets) P.O. q 12 hours; or 250 mg buffered powder P.O. q 12 hours.Adults under 60 kg: 125 mg (tablets) P.O. q 12 hours; or 167 mg buffered powder P.O. q 12 hours.Children: 90 to ISO mg/m 2 P.O. q 12 hours.Dosage adjustment: Dialysis patients should receive 25% of usual dose.ADVERSE REACTIONSCNS: headache, seizures, confusion, anxiety, nervousness, abnormal thinking, twitching, depression, peripheral neuropathy, dizziness, asthenia, insomnia.

CV: hypertension, edema, heart failure.

EENT: retinal changes, optic neuritis.

GI: diarrhea, nausea, vomiting, abdominal pain, pancreatitis, dry mouth, anorexia.

Hematologic: leukopenia, granulocytosis, thrombocytopenia, anemia.

Hepatic: hepatic failure, elevated liver enzymes.

Respiratory: dyspnea, pneumonia .

Skin: rash, pruritus, alopecia.

Other: pain, infection, sarcoma, allergic reactions, myopathy, increased serum uric acid levels, chills, fever.
INTERACTIONS

Drug-drug. Antacids containing magnesium or aluminum hydroxides: enhanced adverse effects of the antacid component (including diarrhea or constipation) when administered with didanosine tablets or pediatric suspension. Avoid concomitant use.

Dapsone, drugs that require gastric acid for adequate absorption, ketoconazole: decreased absorption from buffering action. These drugs are administered 2 hours before didanosine.

Fluoroquinolones, tetracyclines: decreased absorption from buffering agents in didanosine tablets or antacids in pediatric suspension. Avoid concomitant use. Itraconazole: decreased serum levels of itraconazole. Avoid concomitant use.

Drug-food. Any food: decreased rate of absorption. Drug is given on an empty stomach at least 30 minutes before a meal.
EFFECTS ON DIAGNOSTIC TESTS

None reported.
CONTRAINDICATlONS

Contraindicated in patients with history of hypersensitivity to any component of the formulation.
SPECIAL CONSIDERATIONS

* Use cautiously in patients with history of pancreatitis; fatalities have occurred. Also, it is used cautiously in patients with peripheral neuropathy, renal or hepatic impairment, or hyperuricemia. Liver and renal function tests must be monitored.
* Administer didanosine on an empty stomach, regardless of the dosage form used; administering drug with meals can decrease absorption by 50%.
* To administer single-dose packets containing buffered powder for oral solution, contents is poured into 4 oz (120 ml) of water. Fruit juice or other beverages that may be acidic should not be used. Then, mixture is stirred for 2 or 3 minutes until the powder dissolves completely. Drug is administered immediately.
* The powder for oral solution has been associated with a high incidence of diarrhea. The manufacturer suggests switching to the tablet formulation if diarrhea is a problem.

Alert: The pediatric powder for oral solution must be prepared by a pharmacist before dispensing. It must be constituted with purified USP water and then diluted with an antacid (either Mylanta Double Strength liquid or Maalox TC Suspension) to a final concentration of 10 mg/ml. The admixture is stable for 30 days if refrigerated (at 36° to 460 F [2° to 8° C]). The solution should be shaken well beFore measuring the dose.

Alert: Don't confuse drug with other antivirals that use abbreviations for identification.

Patient teaching

* Take drug on an empty stomach.
* Because the tablets contain buffers that raise stomach pH to levels that prevent degradation of the active drug, chew tablets thoroughly before swallowing and drink at least 1 oz (30 ml) of water with each dose. Learn how to prepare crushed tablets or buffered powder form for ingestion, if appropriate.
* If on a sodium-restricted diet, know that each two-tablet dose of didanosine contains 529 mg of sodium; each single packet of buffered powder for oral solution contains 1.38 g of sodium.
* Report symptoms of pancreatitis, such as abdominal pain, nausea, vomiting, diarrhea.


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