Baclofen

CLINICAL USE

Chronic severe spasticity of voluntary muscles

DOSE IN NORMAL RENAL FUNCTION

5 mg, 3 times a day; increase dose gradually up to 100 mg/day

PHARMACOKINETICS

  • Molecular weight                           :213.7
  • %Protein binding                           :30
  • %Excreted unchanged in urine     : 70
  • Volume of distribution (L/kg)       :0.7
  • half-life – normal/ESRD (hrs)      :3–4/–

    DOSE IN RENAL IMPAIRMENT

    GFR (mL/MIN)

  • 20 to 50     : 5 mg, 3 times a day and titrate according to response
  • 10 to 20     : 5 mg, twice a day and titrate according to response
  • <10           : 5 mg, once a day and titrate according to response

    DOSE IN PATIENTS UNDERGOING RENAL REPLACEMENT THERAPIES

  • CAPD                :Unknown dialysability. Dose as in GFR <10 mL/min
  • HD                     :Dialysed.1 Dose as in GFR
  • <10           : mL/min
  • HDF/high flux   :Dialysed.1 Dose as in GFR
  • <10           : mL/min
  • CAV/VVHD      :Unknown dialysability. Dose as in GFR 10 to 20 mL/min

    IMPORTANT DRUG INTERACTIONS

    Potentially hazardous interactions with other drugs

  • Anti-arrhythmics: enhanced muscle relaxant effect with procainamide
  • Antidepressants: enhanced muscle relaxant effect with tricyclics
  • Antihypertensives: enhanced hypotensive effect

    ADMINISTRATION

    Reconstition

    Route

    Oral, intrathecal injection

    Rate of Administration

    Comments

  • Take with or after food
  • Baclofen can be given intrathecally (at doses greatly reduced compared with oral dose), by bolus injection, or continuous infusion. Individual titration of dosage is essential due to variability in response. Test doses must be given. Maintenance dose: 10–2000 micrograms/day

    OTHER INFORMATION

    W

  • ithdraw treatment gradually over 1–2 weeks to avoid anxiety and confusional state, etc
  • Drowsiness and nausea frequent at the start of therapy
  • Use with caution as a case report of encephalopathy has been reported in a haemodialysis patient.
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