Pharm

Carbidopa-Levodopa

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Carbidopa-Levodopa, Levodopa, Carbidopa/Levodopa, Levodopa-Carbidopa, Levodopa/Carbidopa, Sinemet, Stalevo, Dopa decarboxylase inhibitor, Dopamine Precursor, Rytary, Duopa, Inbrija

  • Precautions
  • General pointers
  1. Sinemet (regular release) is by far the single most effective agent
    1. This agent should be the first line and main agent used for Parkinsonism
    2. All other agents are adjuncts only
  2. Dosing Threshold
    1. Identify the individual patient's optimal dose and use this dose at each dosing interval
    2. Using a lower dose below threshold will be inadequate
  3. Food Interactions
    1. Take at least one hour before a meal or 2 hours after a meal
  4. Wearing off of effect
    1. See frequency of dosing of Sinemet below
    2. Most common cause of Insomnia
    3. May cause anxiety, nocturnal cramps
  5. Dyskinesia (e.g. Choreiform movements)
    1. Dyskinesia is more age related than that of duration of Levodopa use
    2. Reducing each Levodopa dose decreases this adverse effect
    3. Amantadine decreases Dyskinesia
  6. Adverse Effects: Educate patients about serious effects (most are reduced by tapering dose)
    1. Drowsiness
    2. Pathologic Gambling, Hypersexuality, Excessive shopping/spending
    3. Hallucinations or Delusions
    4. Swelling
  • Preparations
  1. Carbidopa/Levodopa (Sinemet)
    1. Preferred option over sustained release
      1. Lower cost
      2. Better pharmacokinetics
      3. Less Drug Interactions
    2. Start at 25/100 orally three times daily
    3. Increase by one tablet every 1-2 days as needed
    4. Maximum : 3 tablets per dose, three times daily (no benefit to higher doses, but frequency may be increased)
    5. Frequency of dose
      1. Initially give dose three times daily
      2. Long term, dose may wear off early
        1. Frequency may need to be increased to every 6 hours (at same number of tablets at each dose)
  2. Carbidopa/Levodopa Sustained release (Sinemet CR)
    1. Start at 50/200 orally twice daily
    2. Increase by one tablet every 3 days as needed
    3. Maximum : 8 tablets daily
    4. No benefit over immediate release in motor function, and absorption may be sporadic in some patients
  3. Carbidopa/Levodopa fast onset, sustained release (Rytary)
    1. Onset within 1 hour, duration of 6 hours
    2. Start with lowest dose taken 3 times daily
    3. Costs 3-4 times more than generic Carbidopa/Levodopa
    4. May decrease "off time", the wearing off of activity between doses
    5. Consider in advanced Parkinsonism for "off time" problems despite four time daily dosing
    6. Typical Dose: 3-4 caps three times daily
    7. Requires higher dosing than other preparations due to lower bioavailability
    8. (2015) Presc Lett 22(7): 41
  4. Carbidopa/Levodopa/Entacapone (Stalevo)
    1. Start at 12.5/50/200 PO bid
    2. Increase slowly
    3. Maximum : 8 tablets daily
  5. Carbidopa/Levodopa Enteral Suspension (Duopa)
    1. Convert from immediate release dosing to administer over 16 hours (max daily dose 2000 mg)
  6. Inbrija (inhaled Levodopa)
    1. Indicated in off-time motor rigidity or Tremor
    2. Rapid onset (10 min after inhalation) and duration of 1 hour used for prn "off time" rigidity or Tremor
    3. Less expensive ($30/dose) than Apokyn ($200/dose), an injectable option for off-time
    4. Requires dexterity to replace capsule in Inhaler
    5. Avoid in underlying lung disease (e.g. Asthma, COPD) due to bronchospasm risk
    6. (2019) Presc Lett 26(5)