Videx
didanosine (ddI, 2,3-dideoxyinosine)
Pharmacologic class: Nucleoside reverse transcriptase inhibitor
Therapeutic class: Antiretroviral, antiviral
Pregnancy risk category B
FDA Box Warning
• Pancreatitis has occurred when drug was used alone or in combination regimens in treatment-naive or treatment-experienced patients. Suspend therapy in patients with suspected pancreatitis; discontinue in patients with confirmed pancreatitis.
• Drug may cause lactic acidosis and severe hepatomegaly with steatosis when used alone or in combination with other antiretrovirals. Fatal lactic acidosis has occurred in pregnant women receiving didanosine-stavudine combination with other antiretrovirals. In pregnant patients, use this combination with caution and only if benefit clearly outweighs risk.
Action
Inhibits replication of human immunodeficiency virus (HIV) by disrupting synthesis of DNA polymerase, an enzyme crucial to DNA and RNA formation
Availability
Capsules (delayed-release): 125 mg, 200 mg, 250 mg, 400 mg
Powder for oral solution (pediatric): 2 g in 4-oz glass bottle, 4 g in 8-oz glass bottle
Indications and dosages
➣ HIV infection
Adults weighing 60 kg (132 lb) or more: 400 mg (capsules) P.O. once daily
Adults weighing less than 60 kg (132 lb): 250 mg (capsules) P.O. once daily
Children: 120 mg/m2 (powder for oral solution, pediatric) P.O. q 12 hours
Dosage adjustment
• Renal impairment
Contraindications
• Hypersensitivity to drug
• Concurrent use of allopurinol or ribavirin
Precautions
Use cautiously in:
• renal or hepatic impairment, peripheral neuropathy, hyperuricemia
• elderly patients
• pregnant or breastfeeding patients
• children.
Administration
• Know that drug is usually given in conjunction with other antiretrovirals.
• Give on empty stomach 30 minutes before or 2 hours after a meal.
• Don't administer with fruit juice.
• Know that pharmacist must prepare pediatric powder for oral solution by diluting with water and antacid to a concentration of 10 mg/ml.
• Be aware that delayed-release capsules aren't intended for use in children.
Adverse reactions
CNS: dizziness, anxiety, abnormal thinking, hypoesthesia, agitation, confusion, hypertonia, asthenia, peripheral neuropathy, seizures, coma
CV: peripheral coldness, palpitations, hypotension, bradycardia, weak pulse, pseudoaneurysm, incomplete atrioventricular (AV) block, complete AV block, nodal arrhythmias, ventricular tachycardia, thrombophlebitis, embolism
EENT: diplopia, abnormal vision, ocular hypotony, iritis, retinal detachment
GI: nausea, vomiting, diarrhea, abdominal enlargement, dyspepsia, ileus, GI reflux, hematemesis, dysphagia, dry mouth, pancreatitis
GU: urinary retention, frequency, or incontinence; dysuria; cystalgia; prostatitis; renal dysfunction; nephrotoxicity
Hematologic: anemia, leukocytosis, thrombocytopenia, bleeding, neutropenia
Hepatic: hepatomegaly with steatosis, noncirrhotic portal hypertension
Metabolic: diabetes mellitus, hyperkalemia, lactic acidosis, noncirrhotic portal hypertension
Musculoskeletal: muscle contractions
Respiratory: pneumonia, crackles, rhonchi, bronchitis, pleurisy, dyspnea, wheezing, pleural effusion, pulmonary edema, pulmonary embolism, bronchospasm
Skin: diaphoresis, pallor, rash, urticaria, pruritus, bullous eruption, petechiae, cellulitis, abscess
Other: edema, development of human antichimeric antibodies
Interactions
Drug-drug. Allopurinol, ganciclovir (oral), ribavirin, tenofovir: increased didanosine blood level
Amprenavir, delavirdine, indinavir, ritonavir, saquinavir: altered didanosine pharmacokinetics
Antacids, other drugs that increase gastric pH: increased risk of didanosine toxicity
Co-trimoxazole, pentamidine: increased risk of pancreatic toxicity
Dapsone, fluoroquinolones, ketoconazole: decreased blood levels of these drugs
Itraconazole: decreased itraconazole blood level
Methadone: 50% decrease in didanosine blood level
Drug-diagnostic tests. Alanine aminotransferase, alkaline phosphatase, aspartate aminotransferase, bilirubin, uric acid: increased levels
Granulocytes, hemoglobin, platelets, white blood cells: decreased values
Drug-food. Any food: decreased rate and extent of drug absorption
Patient monitoring
See Monitor patient for signs and symptoms of pancreatitis. Withhold drug in patients with signs or symptoms of pancreatitis and discontinue drug in patients with confirmed pancreatitis.
See Monitor patient for early signs and symptoms of portal hypertension (thrombocytopenia, splenomegaly). Discontinue drug in patients with evidence of noncirrhotic portal hypertension.
See Assess carefully for signs and symptoms of lactic acidosis, such as dizziness, light-headedness, and bradycardia.
• Monitor for signs and symptoms of peripheral neuropathy.
• In patients with renal impairment, watch for drug toxicity and hypermagnesemia (suggested by muscle weakness and confusion).
Patient teaching
• Tell patient to take drug on empty stomach.
• Advise patient using buffered powder to mix it with water, not juice, and to let powder dissolve for several minutes before taking.
See Instruct patient to immediately report abdominal pain, nausea, vomiting, tiredness, fast or irregular heartbeats, easy bruising, difficulty breathing, yellowing of skin or eyes, or dark urine.
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, and foods mentioned above.
didanosine
(dye-dan-oh-seen) didanosine,Videx
(trade name),Videx EC
(trade name)Classification
Therapeutic: antiretroviralsPharmacologic: nucleoside reverse transcriptase inhibitors
Indications
Action
Therapeutic effects
Pharmacokinetics
Time/action profile (antiretroviral plasma levels)
| ROUTE | ONSET | PEAK | DURATION |
| PO | unknown | 0.25–1.5 hr | 12 hr |
Contraindications/Precautions
Adverse Reactions/Side Effects
Central nervous system
- seizures (life-threatening)
- headache (most frequent)
- dizziness
- insomnia
- lethargy
- pain
- weakness
Ear, Eye, Nose, Throat
- rhinitis (most frequent)
- ear pain
- epistaxis
- optic neuritis
- parotid gland enlargement
- photophobia
- retinal depigmentation
- sialoadenitis
Respiratory
- cough (most frequent)
- asthma
Cardiovascular
- arrhythmias
- edema
- hypertension
- vasodilation
Gastrointestinal
- hepatomegaly (with steatosis) (life-threatening)
- liver failure (life-threatening)
- non-cirrhotic portal hypertension (life-threatening)
- pancreatitis (life-threatening)
- anorexia (most frequent)
- diarrhea (most frequent)
- ↑ liver function tests (most frequent)
- nausea (most frequent)
- vomiting (most frequent)
- abdominal pain
- constipation
- dry mouth
- dyspepsia
- flatulence
- stomatitis
Genitourinary
- urinary frequency
Dermatologic
- alopecia
- ecchymoses
- rash
Endocrinologic
- fat redistribution
- hyperglycemia
Hematologic
- granulocytopenia (most frequent)
- anemia
- bleeding
- leukopenia
Metabolic
- lactic acidosis (life-threatening)
- hyperlipidemia
- hyperuricemia
- weight loss
Musculoskeletal
- rhabdomyolysis (life-threatening)
- arthritis
- myalgia
Neurologic
- peripheral neuropathy (most frequent)
- poor coordination
Miscellaneous
- chills (most frequent)
- fever (most frequent)
- anaphylactoid reactions
- immune reconstitution syndrome
Interactions
Drug-Drug interaction
Ribavirin and allopurinol ↑ levels and risk of toxicity (concurrent use not recommended).Levels are ↑ by tenofovir (dose reduction recommended).Concurrent use with ganciclovir ↑ levels (dose adjustments may be necessary).Methadone ↓ levels of didanosine (dose adjustments may be necessary).Buffers in didanosine ↑ absorption of ketoconazole, itraconazole, dapsone, tetracyclines, and fluoroquinolones (do not administer within 2 hr of didanosine).↑ risk of peripheral neuropathy with isoniazid, phenytoin, stavudine, ethambutol, and chloramphenicol (use cautiously).↑ risk of pancreatitis with other alcohol, thiazide diuretics, IV pentamidine, tetracyclines (use with extreme caution).↑ risk of bone marrow depression with other drugs causing bone marrow depression.Concurrent use with stavudine during pregnancy ↑ the risk of fetal lactic acidosis.Administration with food ↓ absorption by 50%.Route/Dosage
Renal Impairment
Oral (Adults >60 kg) CCr 30–59 mL/min— Oral solution—100 mg q 12 hr or 200 mg once daily; Videx EC capsules—200 mg once daily; CCr 10–29 mL/min—Oral solution—150 mg once daily; Videx EC capsules—125 mg once daily; CCr <10 mL/min—Oral solution—100 mg once daily; Videx EC capsules—125 mg once daily.Availability (generic available)
Nursing implications
Nursing assessment
- Monitor for change in severity of HIV symptoms and for symptoms of opportunistic infection before and during therapy.
- Monitor patient for peripheral neuropathy (distal numbness, tingling, or pain in feet or hands) during therapy. Dose may need to be decreased.
- Monitor for symptoms of pancreatitis (abdominal pain, nausea, vomiting, increased amylase, lipase, or triglyceride concentrations). If amylase is elevated 1.5–2 times the normal limit and/or the patient has symptoms of pancreatitis, didanosine should be discontinued. Pancreatitis may be fatal.
- May cause lactic acidosis and severe hepatomegaly with steatosis; increased risk in patients who are female, obese, or receiving nucleoside analog medications for extended periods of time. Monitor patient for signs (increased serum lactate levels, elevated liver enzymes, liver enlargement on palpation). Therapy should be suspended if clinical or laboratory signs occur.
- Assess for signs of non-cirrhotic portal hypertension (elevated liver enzymes, esophageal varices, hematemesis, ascites, and splenomegaly); may occur months or years after starting therapy. Monitor for early signs (thrombocytopenia and splenomegaly) during therapy. Discontinue didanosine if signs occur; may lead to liver transplantation or death.
- Lab Test Considerations: Monitor viral load and CD4 count before and routinely during therapy to determine response.
- Monitor CBC, hepatic function, and uric acid concentrations during therapy. May cause leukopenia, granulocytopenia, thrombocytopenia, and anemia. May cause ↑ AST, ALT, alkaline phosphatase, bilirubin, uric acid, amylase, lipase, and triglyceride concentrations.Lactic acidosis may occur with hepatic toxicity causing hepatic steatosis; may be fatal, especially in women. Monitor liver enzymes, serum bilirubin, albumin, complete blood count, and international normalized ratio (INR) and ultrasonography routinely; may be ↑ in patients with non-cirrhotic portal hypertension.
- May cause hyperglycemia.
- Monitor serum potassium concentrations routinely liver enzymes, serum bilirubin, albumin, complete blood count, and 119 international normalized ratio (INR) and ultrasonography should be considered. VIDEX should 120 be discontinued in patients with evidence of non-cirrhotic portal hypertension.
Potential Nursing Diagnoses
Risk for infection (Indications, Side Effects)Risk for injury (Side Effects)
Implementation
- Commonly identified by abbreviation “ddI,” but generic and brand names should be used when ordering to prevent errors.
- If solution or powder spills or leaks, a wet mop or damp sponge should be used for cleaning to avoid generation of dust. Clean surface with soap and water as needed.
- Oral: Administer every 12 hr on an empty stomach, 30 min before or 2 hr after meals. Do not administer ketoconazole, dapsone, tetracyclines, or fluoroquinolones within 2 hr (6 hr for ciprofloxacin) of didanosine.
- Swallow capsules whole; do not open, crush, or chew.
- Solution for pediatric use is mixed by pharmacist and is stable for 30 days if refrigerated. Shake admixture immediately before administering.
Patient/Family Teaching
- Instruct patient on the importance of taking didanosine exactly as directed, even if feeling better. Caution patient not to share or trade this medication with others.
- May cause dizziness. Caution patient to avoid driving or other activities requiring alertness until response to medication is known.
- Inform patient that didanosine may cause hyperglycemia. Advise patient to notify health care professional if increased thirst or hunger; unexplained weight loss; increased urination; fatigue; or dry, itchy skin occurs.
- Instruct patient to notify health care professional immediately if symptoms of lactic acidosis (tiredness or weakness, unusual muscle pain, trouble breathing, stomach pain with nausea and vomiting, cold especially in arms or legs, dizziness, fast or irregular heartbeat) or if signs of hepatotoxicity (yellow skin or whites of eyes, dark urine, light-colored stools, lack of appetite for several days or longer, nausea, abdominal pain) occur. These symptoms may occur more frequently in patients that are female, obese, or have been taking medications like didanosine for a long time.
- Instruct patient to notify health care professional of all Rx or OTC medications, vitamins, or herbal products being taken and to consult health care professional before taking other Rx, OTC, or herbal products,.
- Caution patient to avoid crowds and persons with known infections.
- Advise patient to notify health care professional immediately if numbness or tingling of the hands or feet, occurs.
- Caution patient to use a condom to prevent transmission of HIV and not to share needles with anyone.
- Inform patient that redistribution and accumulation of body fat may occur, causing central obesity, dorsocervical fat enlargement (buffalo hump), peripheral wasting, breast enlargement, and cushingoid appearance. The cause and long-term effects are not known.
- Children should have dilated retinal exams every 3–6 mo or if there is a change in vision throughout therapy.
- Emphasize the importance of regular exams to monitor for side effects.
Evaluation/Desired Outcomes
- Decreased incidence of opportunistic infection and slowed progression of HIV infection.