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. 2015 Sep;40(9):590–600.

Table 1.

Carbidopa/Levodopa Products22–24,26,30–34,40–48,50

Product
Manufacturer 		Dosinga Mechanism/Pharmacokinetics Potential Adverse Events Monitoring Parameters
Sinemet (carbidopa/levodopa tablet)b
Merck
Parcopa ODT (carbidopa/levodopa ODT)c
Mylan 		10/100 mg
25/100 mg
25/250 mg
Starting dosage: usually 25/100 mg TID; weekly titration based on response

  • Levodopa = dopamine prodrug; crosses BBB; converted to dopamine by dopa decarboxylase.

  • Adding carbidopa blocks peripheral conversion of levodopa to dopamine; more levodopa crosses into CNS, with fewer peripheral adverse events and less levodopa needed.

  • Absorption: proximal small intestine (food may delay); saturable; competes with LNAAs

  • Metabolism: GI tract, kidney, liver

  • Excretion: 70% in urine; half-life: approximately 1 hour

  • CNS: confusion, sedation, vivid dreams, dizziness, hallucinations, psychosis, depression

  • GI: nausea, vomiting, changes in bowel habits

  • Other: orthostasis, leg edema, dyskinesia, dystonia, hemolytic anemia, leukopenia

  • Blood pressure

  • Pulse

  • Changes in

  • mental status

  • Clinical response Note: May turn urine dark or brown/black.
Sinemet CR (carbidopa/levodopa sustained-release tablet)b
Merck 		25/100 mg
50/200 mg
Starting dosage: 50/200 mg BID
Rytary ER (carbidopa/levodopa ER tablet)
Impax Pharmaceuticals 		23.75/95 mg
36.25/145 mg
48.75/195 mg
61.25/245 mg
Dosing is TID and may be increased to five times daily in advanced disease
Duopa (carbidopa/levodopa enteral suspension)
AbbVie 		4.63/20 mg/1 mL (100-mL cassettes); suspension delivered via infusion pump in small intestinee (PEG-J tube)
Stalevo (carbidopa/levodopa/entacapone)b,d
Novartis
Combines carbidopa/levodopa with COMTI		 12.5/50/200 mg
18.75/75/200 mg
25/100/200 mg
31.25/125/200 mg
37.5/150/200 mg
50/200/200 mg
a

A daily carbidopa dose of 75–100 mg is required to inhibit peripheral conversion of levodopa to dopamine. Dose reductions of 10% to 30% may be needed when carbidopa/levodopa is used with other agents, e.g., COMTIs/Stalevo, dopamine agonists, monamine oxidase Binhibitors.

b

Generic available.

c

Parcopa ODT contains phenylalanine; avoid in patients with phenylketonuria.

d

Do not split tablets.

e

Administered into the jejunum via a percutaneous endoscopic gastrostomy with jejunal tube (PEG-J) with an infusion pump.

BBB = blood–brain barrier; BID = twice daily; CNS = central nervous system; COMTI = catechol-O-methyltransferase inhibitor; GI = gastrointestinal; CR = controlled release; ER = extended release; LNAA = large neutral amino acid; ODT = orally disintegrating tablets; TID = three times daily.