The following adverse reactions are discussed in greater detail in other sections:

• Pancreatitis [see BOXED WARNING, WARNINGS AND PRECAUTIONS]
• Lactic acidosis/severe hepatomegaly with steatosis [see BOXED WARNING, WARNINGS AND PRECAUTIONS]
• Hepatic toxicity [see WARNINGS AND PRECAUTIONS]
• Non-cirrhotic portal hypertension [see WARNINGS AND PRECAUTIONS]
• Peripheral neuropathy [see WARNINGS AND PRECAUTIONS]
• Retinal changes and optic neuritis [see WARNINGS AND PRECAUTIONS]

Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

Adults

Selected clinical adverse reactions that occurred in adult patients in clinical studies with VIDEX are provided in Tables 3 and 4.

Table 3: Selected Clinical Adverse Reactions from Monotherapy Studies

Table 4: Selected Clinical Adverse Reactions from Combination Studies

Pancreatitis resulting in death was observed in one patient who received VIDEX (didanosine) plus stavudine plus nelfinavir in Study AI454-148 and in one patient who received VIDEX plus stavudine plus indinavir in the START 2 study. In addition, pancreatitis resulting in death was observed in 2 of 68 patients who received VIDEX plus stavudine plus indinavir plus hydroxyurea in an ACTG clinical trial [see WARNINGS AND PRECAUTIONS].

The frequency of pancreatitis is dose related. In phase 3 studies, incidence ranged from 1% to 10% with doses higher than are currently recommended and from 1% to 7% with recommended dose.

Selected laboratory abnormalities in clinical studies with VIDEX are shown in Tables 5-7.

Table 5: Selected Laboratory Abnormalities from Monotherapy Studies

Table 6: Selected Laboratory Abnormalities from Combination Studies (Grades 3-4)

Table 7: Selected Laboratory Abnormalities from Combination Studies (All Grades)

Pediatric Patients

In clinical trials, 743 pediatric patients between 2 weeks and 18 years of age have been treated with didanosine. Adverse reactions and laboratory abnormalities reported to occur in these patients were generally consistent with the safety profile of didanosine in adults.

In pediatric phase 1 studies, pancreatitis occurred in 2 of 60 (3%) patients treated at entry doses below 300 mg/m²/day and in 5 of 38 (13%) patients treated at higher doses. In study ACTG 152, pancreatitis occurred in none of the 281 pediatric patients who received didanosine 120 mg/m² every 12 hours and in less than 1% of the 274 pediatric patients who received didanosine 90 mg/m² every 12 hours in combination with zidovudine [see Clinical Studies].

Retinal changes and optic neuritis have been reported in pediatric patients.

Postmarketing Experience

The following adverse reactions have been identified during postapproval use of didanosine. Because they are reported voluntarily from a population of unknown size, estimates of frequency cannot be made. These reactions have been chosen for inclusion due to their seriousness, frequency of reporting, causal connection to VIDEX, or a combination of these factors.

Blood and Lymphatic System Disorders – anemia, leukopenia, and thrombocytopenia.

Body as a Whole – alopecia, anaphylactoid reaction, asthenia, chills/fever, pain, and redistribution/accumulation of body fat [see WARNINGS AND PRECAUTIONS].

Digestive Disorders – anorexia, dyspepsia, and flatulence.

Exocrine Gland Disorders – pancreatitis (including fatal cases) [see BOXED WARNING, WARNINGS AND PRECAUTIONS], sialoadenitis, parotid gland enlargement, dry mouth, and dry eyes.

Hepatobiliary Disorders – symptomatic hyperlactatemia/lactic acidosis and hepatic steatosis [see BOXED WARNING, WARNINGS AND PRECAUTIONS]; non-cirrhotic portal hypertension [see WARNINGS AND PRECAUTIONS]; hepatitis and liver failure.

Metabolic Disorders – diabetes mellitus, hypoglycemia, and hyperglycemia.

Musculoskeletal Disorders – myalgia (with or without increases in creatine kinase), rhabdomyolysis including acute renal failure and hemodialysis, arthralgia, and myopathy.

Ophthalmologic Disorders – retinal depigmentation and optic neuritis [see WARNINGS AND PRECAUTIONS].

Use with Stavudine- and Hydroxyurea-Based Regimens

When didanosine is used in combination with other agents with similar toxicities, the incidence of these toxicities may be higher than when didanosine is used alone. Thus, patients treated with VIDEX in combination with stavudine, with or without hydroxyurea, may be at increased risk for pancreatitis and hepatotoxicity, which may be fatal, and severe peripheral neuropathy [see WARNINGS AND PRECAUTIONS]. The combination of VIDEX and hydroxyurea, with or without stavudine, should be avoided.

Read the Videx (didanosine pediatric powder for oral solution) Side Effects Center for a complete guide to possible side effects »

Established Drug Interactions

Clinical recommendations based on the results of drug interaction studies are listed in Table 8. Pharmacokinetic results of drug interaction studies are shown in Tables 12 and 13 [see CONTRAINDICATIONS, CLINICAL PHARMACOLOGY].

Table 8: Established Drug Interactions with VIDEX

Exposure to didanosine is increased when coadministered with tenofovir disoproxil fumarate [Table 8 and see CLINICAL PHARMACOKINETICS, Table 12)]. Increased exposure may cause or worsen didanosine-related clinical toxicities, including pancreatitis, symptomatic hyperlactatemia/lactic acidosis, and peripheral neuropathy. Coadministration of tenofovir disoproxil fumarate with VIDEX should be undertaken with caution, and patients should be monitored closely for didanosine-related toxicities and clinical response. VIDEX should be suspended if signs or symptoms of pancreatitis, symptomatic hyperlactatemia, or lactic acidosis develop [see DOSAGE AND ADMINISTRATION, WARNINGS AND PRECAUTIONS]. Suppression of CD4 cell counts has been observed in patients receiving tenofovir disoproxil fumarate with didanosine at a dose of 400 mg daily.

Predicted Drug Interactions

Predicted drug interactions with VIDEX are listed in Table 9.

Table 9: Predicted Drug Interactions with VIDEX

Last reviewed on RxList: 12/6/2011
This monograph has been modified to include the generic and brand name in many instances.