didanosine (Rx)

Brand and Other Names:Videx, Videx EC
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Dosing & Uses

AdultPediatric

Dosage Forms & Strengths

capsule, extended release

  • 125mg
  • 200mg
  • 250mg
  • 400mg

powder for oral solution

  • 2 g
  • 4 g
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HIV Infection

≤60 kg: Extended-release 250 mg PO qDay; 125 mg PO q12hr

>60 kg: Extended-release 400 mg PO qDay; suspension 200 mg PO q12hr

Dosage Modifications

Coadministration with tenofovir

  • >60 kg: Decrease didanosine dose to 250 mg/day
  • ≤60 kg: Decrease didanosine dose to 200 mg/day

Renal Impairment

>60 kg

  • CrCl >60 mL/min: Normal dose
  • CrCl 30-59 mL/min: 200 mg PO qDay (extended release/solution) or divided q12hr (solution only)
  • CrCl 10-29 mL/min: 125 mg (extended release) or 150 mg (solution) PO qDay
  • CrCl <10 mL/min; PD/HD: 125 mg (extended release) or 100 mg (solution) PO qDay

≤60 kg

  • CrCl >60 mL/min: Normal dose
  • CrCl 30-59 mL/min: Extended release 125 mg PO qDay; solution 150 mg PO qDay or divided q12hr
  • CrCl 10-29 mL/min: 125 mg (extended release) or 100 mg (solution) PO qDay
  • CrCl <10 mL/min; PD/HD: Solution only: 75 mg PO qDay

Dosing Consideration

Monitoring

  • Amylase q4-8Weeks; CBC with different, aminotransferases, K+, triglycerides q6-12Weeks
  • Neurologic evaluation q4Weeks
  • Periodic retinal exams

Dosage Forms & Strengths

capsule, extended release

  • 125mg
  • 200mg
  • 250mg
  • 400mg

powder for oral solution

  • 10mg/mL (reconstituted)

tablet for oral suspension

  • 100mg
  • 150mg
  • 200mg
more...

HIV Infection

Indicated for treatment of HIV infection in combination with other antiretroviral agents

Oral solution

  • NIH HIV guidelines (March 2016)
    • 2 weeks to <3 months: 50 mg/m² PO q12hr 
    • 3-8 months: 100 mg/m² PO q12hr
    • >8 months: 120 mg/m² (range 90-150 mg/m²) PO q12hr
  • Manufacturer prescribing information
    • 2 week to 8 months: 100 mg/m² PO q12hr
    • >8 months: 120 mg/m² PO q12hr

Capsule

  • Weight-based dosing (6-18 years)
    • Children who can safely swallow enteric-coated beadlets or delayed-release capsules (Videx EC or generic capsules)
    • 20 to <25 kg: 200 mg PO qDay
    • 25 to <60 kg: 250 mg PO qDay
    • ≥60 kg: As adults; 400 mg PO qDay (oral suspension: 200 mg PO q12hr)

Dosing Consideration

Monitoring

  • Amylase q4-8Weeks; CBC with different, aminotransferases, K+, triglycerides q6-12Weeks
  • Neurologic evaluation q4Weeks
  • Periodic retinal exams
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Interactions

Interaction Checker

and didanosine

No Results

     activity indicator 
    No Interactions Found
    Interactions Found

    Contraindicated

      Serious - Use Alternative

        Significant - Monitor Closely

          Minor

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            Adverse Effects

            >10%

            Diarrhea (19-28%)

            Peripheral neuropathy (17-20%)

            Increased amylase (15-17%)

            Abdominal pain (7-13%)

            1-10%

            Increased LFT

            Increased uric acid

            Pancreatitis (patients >65 years had higher frequency of pancreatitis than younger patients)

            Pruritus

            Rash

            Postmarking Reports

            Noncirrhotic portal hypertension

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            Warnings

            Black Box Warnings

            Fatal and nonfatal pancreatitis reported; suspend if pancreatitis suspected and discontinue if confirmed

            Lactic acidosis and severe hepatomegaly with steatosis (including fatal cases) reported with use of nucleoside analogues alone or in combination

            Fatal lactic acidosis reported in pregnant women who have received didanosine and stavudine with other antiretroviral agents. Use the combination with caution in pregnant women

            Contraindications

            Hypersensitivity

            Coadministration with allopurinol (may increase didanosine toxicity)

            Coadministration with ribavirin (increases actrive metabolite dideoxyadenosine 5’-triphosphate levels, causing fatal hepatic failure, peripheral neuropathy, pancreatitis, and symptomatic hyperlactatemia/lactic acidosis)

            Cautions

            (All NRTIs): Risk of potentially fatal lactic acidosis & severe hepatomegaly with steatosis when used alone or in combination with other antiretrovirals

            Risk of potentially fatal pancreatitis, increases if used in combo with stavudine

            Risk of potentially fatal bleeding from esophageal varices in patients with non-cirrhotic portal hypertension

            Discontinue if pancreatitis occurs; reduce dose for other ADR's

            Risk of immune reconstitution syndrome if used in combination w/ other antiretroviral drugs

            Risk of retinal changes and optic neuritis

            Rapidly degrades in acidic pH, however, EC is protected from stomach acids

            Noncirrhotic portal hypertension reported; discontinue if signs/symptoms occur (eg, elevated liver enzymes, esophageal varices, hematemesis, ascites, splenomegaly)

            Coadministration of methadone with Videx pediatric powder may significant decrease didanosine concentrations

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            Pregnancy & Lactation

            Pregnancy Category: B

            Lactation: Not known whether distributed into milk. Because of both the potential for HIV transmission and the potential for serious adverse reactions in nursing infants, mothers should be instructed not to breastfeed.

            Pregnancy Categories

            A:Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

            B:May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

            C:Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

            D:Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

            X:Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

            NA:Information not available.

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            Pharmacology

            Mechanism of Action

            Nucleoside Reverse Transcriptase Inhibitor (NRTI)

            Inhibits in vitro replication of HIV via chain termination & interference with HIV-RNA dependent DNA polymerase

            Pharmacokinetics

            Bioavailability: 42% (adults); 25% (children)

            Protein Bound: <5%

            Metabolism: Liver

            Excretion: Urine

            Vd: 28 L/m² (children); 1.08 L/kg

            Half-life elimination: 0.8 hr (children and adolescents); 1.5 hr (adults)

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            Administration

            Powder for Oral Solution Preparation

            Prior to dispensing, the pharmacist must reconstitute dry powder to an initial concentration of 20 mg/mL and immediately mix the resulting solution with antacid to a final concentration of 10 mg/mL

            Initial solution (20 mg/mL): Reconstitute the product to 20 mg per mL by adding 100 mL or 200 mL of purified water USP, to the 2 g or 4 g of powder, respectively

            Final solution (10 mg/mL): Immediately mix one part of the 20 mg/mL initial solution with one part of any commercially available antacid that contains as active ingredients aluminum hydroxide (400 mg/5 mL), magnesium hydroxide (400 mg/5 mL), and simethicone (40 mg/5 mL) for a final dispensing concentration of 10 mg/mL

            Oral Administration

            Oral solution dispensed as 10 mg/mL with antacid as diluent

            Take on empty stomach, at least 30 minutes before food or 2 hr after food; Cmax and AUC reduced by ~46% and 19% respectively in the presence of food

            EC not approved for aged <6 yr and for children who weigh <20 kg and unable to swallow capsule whole

            Storage

            Reconstituted oral solution (10 mg/mL): Refrigerate for up to 30 days at 36-46°F (2-8°C); discard any unused portion after 30 days

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            Formulary

            FormularyPatient Discounts

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            The above information is provided for general informational and educational purposes only. Individual plans may vary and formulary information changes. Contact the applicable plan provider for the most current information.

            Tier Description
            1 This drug is available at the lowest co-pay. Most commonly, these are generic drugs.
            2 This drug is available at a middle level co-pay. Most commonly, these are "preferred" (on formulary) brand drugs.
            3 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs.
            4 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            5 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            6 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            NC NOT COVERED – Drugs that are not covered by the plan.
            Code Definition
            PA Prior Authorization
            Drugs that require prior authorization. This restriction requires that specific clinical criteria be met prior to the approval of the prescription.
            QL Quantity Limits
            Drugs that have quantity limits associated with each prescription. This restriction typically limits the quantity of the drug that will be covered.
            ST Step Therapy
            Drugs that have step therapy associated with each prescription. This restriction typically requires that certain criteria be met prior to approval for the prescription.
            OR Other Restrictions
            Drugs that have restrictions other than prior authorization, quantity limits, and step therapy associated with each prescription.
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