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Drugs reference index «Didanosine»

Didanosine

Pronunciation: (dye-DAN-oh-seen)Class: Nucleoside reverse transcriptase inhibitor

Trade Names:Videx- Powder for oral solution, pediatric 2 g- Powder for oral solution, pediatric 4 g

Trade Names:Videx EC- Capsules, delayed-release (with enteric-coated beadlets) 125 mg- Capsules, delayed-release (with enteric-coated beadlets) 200 mg- Capsules, delayed-release (with enteric-coated beadlets) 250 mg- Capsules, delayed-release (with enteric-coated beadlets) 400 mg

Pharmacology

Inhibits replication of HIV by interfering with DNA synthesis.

Pharmacokinetics

Absorption

T max is 0.25 to 1.5 h (buffered formulation), 2 h (delayed-release). Bioavailability is approximately 42% (buffered formulation). Food decreases the C max and AUC by approximately 55% when didanosine tablets were administered up to 2 h after a meal. C max and AUC of the delayed-release capsules decreased by approximately 46% and 19%, respectively, in the presence of food. Should be taken on an empty stomach.

Distribution

Less than 5% protein bound. Vd is approximately 43.7 L/m 2 .

Elimination

Half-life is approximately 1.5 h (buffered formulation). Approximately 18% recovered in the urine (buffered formulation). Renal Cl is approximately 458 mL/min (buffered formulation) in patients with CrCl of at least 90 mL/min.

Special Populations

Renal Function Impairment

Half-life is increased and Cl is decreased. Dosage reduction recommended in those with CrCl less than 60 mL/min.

Hepatic Function Impairment

Mean C max and AUC were 19% and 13% higher, respectively. No dosage adjustment required.

Indications and Usage

Treatment of HIV-1 infection in combination with other antiretrovirals.

Contraindications

Standard considerations.

Dosage and Administration

VidexAdults

PO

Patients weighing 60 kg or more

200 mg twice daily. For patients who require once-daily dosing, administer 400 mg once daily.

Patients weighing less than 60 kg

125 mg twice daily. For patients who require once-daily dosing, administer 250 mg once daily.

Children

PO

2 wk to 8 mo of age

100 mg/m 2 twice daily.

Older than 8 mo of age

120 mg/m 2 twice daily.

Videx ECAdults and Children

PO

Patients weighing 20 kg to less than 25 kg

200 mg once daily.

Patients weighing 25 kg to less than 60 kg

250 mg once daily.

Patients weighing 60 kg or more

400 mg once daily.

Renal Function ImpairmentAdults

PO

Videx CrCl 60 mL/min or more

For patients weighing at least 60 kg, administer 200 mg twice daily; for patients weighing less than 60 kg, administer 125 mg twice daily.

CrCl 30 to 59 mL/min

For patients weighing at least 60 kg, administer 200 mg once daily or 100 twice daily; for patients weighing less than 60 kg, administer 150 mg once daily or 75 mg twice daily.

CrCl 10 to 29 mL/min

For patients weighing at least 60 kg, administer 150 mg once daily; for patients weighing less than 60 kg, administer 100 mg once daily.

CrCl less than 10 mL/min and patients requiring continuous ambulatory peritoneal dialysis or hemodialysis

For patients weighing at least 60 kg, administer 100 mg once daily; for patients weighing less than 60 mg, administer 75 mg once daily.

Videx EC CrCl 60 mL/min or more

For patients weighing at least 60 kg, administer 400 mg once daily; for patients weighing less than 60 kg, administer 250 mg once daily.

CrCl 30 to 59 mL/min

For patients weighing at least 60 kg, administer 200 mg once daily; for patients weighing less than 60 kg, administer 125 mg once daily.

CrCl 10 to 29 mL/min

Administer 125 mg.

CrCl less than 10 mL/min and patients requiring continuous ambulatory peritoneal dialysis or hemodialysis

For patients weighing at least 60 kg, administer 125 mg once daily; do not administer to patients weighing less than 60 kg.

Concomitant Tenofovir Disoproxil FumarateAdults

PO

Videx EC CrCl 60 mL/min or more and weighing at least 60 kg

Administer 250 mg once daily.

CrCl 60 mL/min or more and weighing less than 60 kg

Administer 200 mg once daily.

General Advice

  • Give on an empty stomach.
  • Pediatric powder for oral suspension is first mixed with purified water to obtain a concentration of 20 mg/mL, then mixed with an antacid to obtain final concentration of 10 mg/mL.
  • Delayed-release capsule should be swallowed whole. Do not break, crush, or chew.
  • Shake solution well before using.
  • Videx EC : Patients with symptoms of peripheral neuropathy may tolerate a reduced dose after resolution of symptoms. If symptoms recur, consider permanently discontinuing treatment.
  • Videx EC : When coadministered with tenofovir disoproxil fumarate, administration with a light meal (400 kcal or less, 20% fat or less) or in the fasted state is recommended.
  • Videx : Administer on an empty stomach, at least 30 min before or 2 h after eating.

Storage/Stability

Videx

Store powder at 59° to 86°F. Once mixed, store for up to 30 days in refrigerator at 36° to 46°F. Discard unused portion after 30 days.

Videx EC

Store at 59° to 86°F.

Drug Interactions

Allopurinol

Because allopurinol may cause increased didanosine plasma levels, do not coadminister.

Antacids

Aluminum- or magnesium-containing antacids may potentiate adverse reactions associated with the antacid component of didanosine pediatric powder.

Antiretroviral agents

Antiretroviral agents have caused fatal lactic acidosis in women when coadministered with didanosine.

Delavirdine, indinavir

Administer 1 h prior to didanosine to avoid decreasing plasma levels of delavirdine or indinavir.

Drugs that cause peripheral neuropathy or pancreatitis

Increased risk of these toxicities.

Food

Reduces absorption of didanosine by as much as 50%.

Fluoroquinolones, tetracyclines

Do not administer within 2 h of didanosine.

Ganciclovir, valganciclovir

Didanosine plasma concentrations may be elevated, increasing the risk of toxicity.

Itraconazole, ketoconazole, dapsone, and other drugs whose absorption can be affected by gastric acidity

Administer at least 2 h before didanosine.

Methadone

May decrease didanosine plasma levels.

Ribavirin

Risk of didanosine toxicity may be increased. Avoid coadministration.

Tenofovir disoproxil fumarate

Didanosine plasma concentrations may be increased, necessitating a dose reduction in didanosine.

Laboratory Test Interactions

None well documented.

Adverse Reactions

Incidences of the following adverse reactions were reported with didanosine monotherapy. When didanosine is used in combination with other agents with similar adverse reactions, the incidence of these reactions, including pancreatitis and hepatotoxicity, may be higher than with didanosine alone.

CNS

Peripheral neurologic symptoms/neuropathy (20%); asthenia (postmarketing).

Dermatologic

Rash/pruritus (9%); alopecia (postmarketing).

EENT

Dry eyes, optic neuritis, retinal depigmentation (postmarketing).

GI

Diarrhea (28%); pancreatitis (7%); anorexia, dry mouth, dyspepsia, flatulence, inflammation of the salivary gland (postmarketing).

Genitourinary

Acute renal failure (postmarketing).

Hepatic

Hepatitis, liver failure, symptomatic hyperlactatemia/lactic acidosis and hepatic steatosis (postmarketing).

Hematologic-Lymphatic

Anemia, leukopenia, thrombocytopenia (postmarketing).

Hypersensitivity

Anaphylactic reactions (postmarketing).

Lab Tests

Elevated serum amylase (17%); elevated ALT and AST (9%); elevated serum alkaline phosphatase (4%); elevated serum uric acid (3%); elevated serum gamma-glutamyltransferase, hyperglycemia, hypoglycemia (postmarketing).

Metabolic-Nutritional

Diabetes mellitus, redistribution/accumulation of body fat (postmarketing).

Musculoskeletal

Arthralgia, myalgia, myopathy, rhabdomyolysis (postmarketing).

Miscellaneous

Abdominal pain (13%); chills/fever, pain, parotid gland enlargement (postmarketing).

Precautions

Warnings

Pancreatitis

Fatal and nonfatal pancreatitis have occurred during therapy regardless of the degree of immunosuppression. Withhold treatment in patients with suspected pancreatitis and discontinue in patients with confirmed pancreatitis.

Lactic acidosis and severe hepatomegaly

Lactic acidosis and severe hepatomegaly with steatosis, including fatal cases, have been reported. Fatal lactic acidosis has been reported in pregnant women receiving the combination of didanosine and stavudine with other antiretroviral agents.

Monitor

Monitor for diarrhea in patients receiving oral solution. Monitor uric acid levels closely for possible asymptomatic hyperuricemia.

Pregnancy

Category B .

Lactation

Undetermined. HIV-infected mothers should not breast-feed infants.

Children

Safety and efficacy not established in children younger than 2 wk of age.

Elderly

Select dose with caution because of greater likelihood of decreased renal function.

Renal Function

Dosage reduction is recommended with CrCl less than 60 mL/min. Adjust dose in renal impairment.

Hepatic Function

Hepatic failure has occurred in children. Dose adjustment is not needed. Hepatotoxicity and hepatic failure resulting in death have been reported during postmarketing experience in patients receiving hydroxyurea and other antiretroviral agents.

Mutagenesis

May be genotoxic.

Fat redistribution

Redistribution/accumulation of body fat (eg, central obesity, dorsocervical fat enlargement [buffalo hump]) has been observed in patients receiving antiretroviral therapy.

Hepatomegaly with steatosis

Fatal cases of severe hepatomegaly with steatosis have been reported.

Hyperuricemia

Asymptomatic hyperuricemia may occur.

Immune reconstitution syndrome

Has been reported in patients receiving combination antiretroviral therapy, including didanosine. During the initial phase of treatment, patients may develop an inflammatory response to indolent or residual opportunistic infections (eg, Mycobacterium avium ), necessitating further evaluation and treatment.

Peripheral neuropathy

Occurs frequently; may be dose-related.

Retinal changes and optic neuritis

Retinal changes and optic neuritis have been reported in adults and children.

Special diets

Each single-dose powder packet contains sodium 1,380 mg.

Overdosage

Symptoms

Diarrhea, hepatic dysfunction, hyperuricemia, pancreatitis, peripheral neuropathy.

Patient Information

  • Advise patient to take drug on empty stomach.
  • Inform patient that drug does not completely eliminate HIV virus and, therefore, does not reduce risk of transmitting HIV. Appropriate precautions must be continued.
  • Emphasize that drug does not cure AIDS or AIDS-related complex (ARC) and to report significant changes in health to health care provider.
  • Instruct patient to report these symptoms to health care provider: abdominal pain, fever, diarrhea, nausea, sore throat, flu-like symptoms, tingling pain or numbness in hands or feet, vomiting.
  • Advise patient to avoid alcoholic beverages.
  • Advise patient not to take any medicine, vitamins, or herbal products without first checking with their health care provider.

Copyright © 2009 Wolters Kluwer Health.

  • Didanosine Detailed Consumer Information (PDR)
  • Didanosine Prescribing Information (FDA)
  • Didanosine Chewable/Dispersible Buffered Tablets MedFacts Consumer Leaflet (Wolters Kluwer)
  • didanosine Concise Consumer Information (Cerner Multum)
  • didanosine Advanced Consumer (Micromedex) - Includes Dosage Information
  • Videx Prescribing Information (FDA)
  • Videx EC Prescribing Information (FDA)
  • Videx EC Delayed-Release Enteric-Coated Capsules MedFacts Consumer Leaflet (Wolters Kluwer)

See Also...

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