Didanosine Side Effects

Brand Names: Videx EC, Videx

Please note - some side effects for Didanosine may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA at http://www.fda.gov/medwatch/ or 1-800-FDA-1088 (1-800-332-1088).

Side Effects of Didanosine - for the Consumer

Didanosine Chewable/Dispersible Buffered Tablets

All medicines may cause side effects, but many people have no, or minor side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Didanosine Chewable/Dispersible Buffered Tablets:

Breast enlargement; changes in body fat; darkened complexion with purple markings; diarrhea; dry mouth; headache; itching; muscle pain; skin and facial wasting; vomiting.

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); blurred vision or other vision changes; chest pain or discomfort, numbness of an arm or leg, or shortness or breath; confusion; dark urine; dizziness; fainting; fast, shallow breathing; fast, slow, or irregular heartbeat; fever or chills; lightheadedness; low body temperature; nausea and vomiting; numbness, tingling, or pain in hands or feet; seizures; severe muscle pain or cramping; stomach pain; tiredness; weakness; yellowing of skin or eyes.

Didanosine Delayed-Release Enteric-Coated Capsules

All medicines may cause side effects, but many people have no, or minor side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Didanosine Delayed-Release Enteric-Coated Capsules:

Breast enlargement; changes in body fat; darkened complexion with purple markings; diarrhea; dry mouth; headache; itching; muscle pain; skin and facial wasting.

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); blurred vision or other vision changes; chest pain or discomfort, numbness of an arm or leg, or shortness of breath; confusion; dark urine; dizziness; fainting; fast, shallow breathing; fast, slow, or irregular heartbeat; fever or chills; lightheadedness; low body temperature; nausea or vomiting; numbness, tingling, or pain in hands or feet; seizures; severe muscle pain or cramping; stomach pain; tiredness; weakness; yellowing of skin or eyes.

Didanosine Powder Pack

All medicines may cause side effects, but many people have no, or minor side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Didanosine Powder Pack:

Breast enlargement; changes in body fat; darkened complexion with purple markings; diarrhea; dry mouth; headache; itching; muscle pain; skin and facial wasting.

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); blurred vision or other vision changes; chest pain or discomfort, numbness of an arm or leg, or shortness of breath; confusion; dark urine; dizziness; fainting; fast, shallow breathing; fast, slow, or irregular heartbeat; fever or chills; lightheadedness; low body temperature; nausea or vomiting; numbness, tingling, or pain in hands or feet; seizures; severe muscle pain or cramping; stomach pain; tiredness; weakness; yellowing of skin or eyes.

Didanosine Solution

All medicines may cause side effects, but many people have no, or minor side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Didanosine Solution:

Breast enlargement; changes in body fat; darkened complexion with purple markings; diarrhea; dry mouth; headache; itching; muscle pain; skin and facial wasting.

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); blurred vision or other vision changes; chest pain or discomfort, numbness of an arm or leg, or shortness of breath; confusion; dark urine; dizziness; fainting; fast, shallow breathing; fast, slow, or irregular heartbeat; fever or chills; lightheadedness; low body temperature; nausea or vomiting; numbness, tingling, or pain in hands or feet; seizures; severe muscle pain or cramping; stomach pain; tiredness; weakness; yellowing of skin or eyes.

Didanosine Side Effects - for the Professional

Didanosine

• In adults, the most common adverse reactions (greater than 10%, all grades) are diarrhea, peripheral neurologic symptoms/neuropathy, nausea, headache, rash, and vomiting. (6.1)
• Adverse reactions in pediatric patients were consistent with those in adults. (6.1)

Side Effects by Body System

General

Many of the side effects associated with nucleoside reverse transcriptase inhibitor therapy (myopathy, pancreatitis, liver failure, lactic acidosis, etc.) are attributable to their direct toxic effect on mitochondria which causes decreased mitochondrial energy-generating capacity.

Patients with renal dysfunction and/or liver disease may be at increased risk of toxicity due to decreased clearance of didanosine.

The adverse effects of didanosine are sometimes difficult to distinguish from the symptomatology observed during the clinical course of AIDS, as well as from the possible adverse effects of other drugs used in the treatment of HIV infection. During the Expanded Access Program (EAP), adverse effects resulted in drug discontinuation in 42% of patients with AIDS and 34% of patients with ARC.

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. Patients treated with didanosine in combination with stavudine, with or without hydroxyurea, may be at an increased risk for pancreatitis and fatal/nonfatal hepatotoxicity, and severe peripheral neuropathy.

Gastrointestinal

Gastrointestinal side effects have included pancreatitis, which has resulted in several deaths. During the EAP in which patients received clinically recommended dosages, the incidence at 5 months for pancreatitis, increased amylase, or abdominal pain was 5% to 8%. Nausea (8% to 23%), dry mouth (23%), diarrhea (17% to 23%), vomiting, and elevated lipase have been reported. Anorexia, dyspepsia, flatulence, sialoadenitis, and parotid gland enlargement have been reported during postmarketing experience.

The factors that increase the risk of pancreatitis in patients with HIV infection are an AIDS diagnosis, CD4+ count less than 100 cells/mm3, baseline hyperamylasemia, substantial alcohol intake, elevated liver transaminases, concurrent treatment with pancreatotoxic medications, and prior history. Resolution is generally seen 2 to 3 weeks following discontinuation of therapy, although fatal cases have been reported. Permanent discontinuation of didanosine in patients developing pancreatitis is suggested, because rechallenge often results in recurrent disease.

A retrospective cohort study evaluated the risk of pancreatitis with didanosine combination therapy. Patients with HIV can develop pancreatitis from the virus itself or from direct toxicity of several antiretroviral drugs.

Hepatic

Lactic acidosis and severe hepatomegaly with steatosis, including fatal cases, have been reported with the use of nucleoside analogs alone or in combination with other antiretroviral agents. Caution should be exercised when administering didanosine to any patient with known risk factors for liver disease. However, cases have also been reported in patients with no known risk factors. Fatal lactic acidosis has been reported in pregnant women who received the combination of didanosine and stavudine with other antiretroviral agents.

Hyperlactatemia and lactic acidosis are often a life-threatening and serious concern with the use of didanosine in combination with other antiretrovirals. Lactate elevation is a common issue in patients on stable antiretroviral therapy and increased levels without acidosis may result from increased production, release, or diminished clearance.

HIV reverse transcriptase inhibitors are competitive inhibitors of DNA polymerase and the greatest affinity appears to be in the mitochondria. Depletion of mitochondrial DNA diminishes cellular respiratory function leading to increased production of lactic acid. Excess lactic acid leaks out of the cell into systemic circulation and can progress to lactic acidosis if hydrogen ions drop the blood pH. Additionally, disturbances in metabolic homeostasis with antiretrovirals can cause hypertriglyceridemia and insulin resistance leading to steatohepatitis and decreased liver function.

Hyperlactatemia appears to be more common with didanosine while lactic acidosis is an infrequent occurrence.

In a report following patients on combined therapy with didanosine and tenofovir, one patient developed didanosine-related toxicity characterized by lactic acidosis with liver failure after 3 months on didanosine 200 mg/day with tenofovir.

Hepatic side effects have included elevated AST (SGOT), ALT (SGPT), and bilirubin. In addition, fulminant hepatitis has been associated with didanosine and has resulted in death. Symptomatic hyperlactatemia, lactic acidosis and hepatic steatosis, hepatitis, and liver failure have been reported during postmarketing experience.

Nervous system

Nervous system side effects have been reported as the most common serious adverse effects of didanosine. Peripheral neuropathy occurred in 16% of patients treated during the EAP. Early trials of didanosine therapy reported a higher incidence. Those studies, however, used higher dosages than more recent trials using lower therapeutic dosages and early trials included patients with very advanced HIV disease. One-year rates of developing peripheral neuropathy ranged from 6% to 15% in the latter trials. Other nervous system side effects have included headache (10%), insomnia (30%), restlessness, and seizures.

Neuropathy presents as tingling, numbness, or pain in the hands or soles of the feet which progresses up the legs. The incidence is higher in patients with a history of neuropathy and/or low CD4+ counts (less than 50 cells/mm3). Following discontinuation of didanosine, neuropathy usually resolves within 2 to 12 weeks.

Metabolic

Metabolic side effects have included elevated serum uric acid, serum alkaline phosphatase, serum amylase, and serum gamma-glutamyltransferase during postmarketing experience. Hyperuricemia developed in 4% of patients treated during the EAP.

There has been one case report of acute gouty arthritis developing 14 weeks after didanosine was added to the treatment regimen of a patient receiving ritonavir, both known to infrequently cause hyperuricemia. The symptoms resolved upon discontinuation of didanosine and a short course of indomethacin.

Hematologic

Hematologic side effects have included anemia, neutropenia, and thrombocytopenia in 2% to 8% of patients. Leukopenia has been reported during postmarketing experience.

Cardiovascular

Cardiovascular side effects have rarely included dyspnea, orthopnea, edema, pericarditis, and left ventricular failure. Underlying cardiomyopathy may be aggravated by treatment with didanosine due to high sodium content in the various dosage forms.

Ocular

Diffuse dysfunction of the retinal epithelium has been reported in two patients during therapy with didanosine. Both patients experienced bilateral visual deficit including night blindness and a peripheral visual fold reduction. Symptoms were first noted after 31 and 34 weeks of therapy. Deficits in both patients appeared to be partially reversible upon discontinuation of didanosine.

Ocular side effects have included retinal changes and optic neuritis. Dry eyes and retinal depigmentation have been reported during postmarketing experience.

Endocrine

Endocrine side effects are uncommon but have included hypertriglyceridemia, impaired glucose tolerance, hyperglycemia, and hypoglycemia. Insulin-dependent diabetes mellitus has also been reported.

Dermatologic

Dermatologic side effects have included rash/pruritus (7% to 9%) and at least one case of cutaneous leukocytoclastic vasculitis. Alopecia has been reported during postmarketing experience.

Other

Other side effects have included asthenia, chills, fever, pain, and redistribution/accumulation of body fat during postmarketing experience.

Musculoskeletal

Musculoskeletal side effects have included myalgia with or without increases in creatine kinase, rhabdomyolysis (including acute renal failure and hemodialysis), arthralgia, and myopathy during postmarketing experience.

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