No

Anti-Parkinson's Agent (Dopamine Agonist)

Treatment of Parkinson's disease

C

Hypersensitivity to levodopa or any component; narrow-angle glaucoma; use of MAO inhibitors within prior 14 days (however, may be administered concomitantly with the manufacturer's recommended dose of an MAO inhibitor with selectivity for MAO type B); history of melanoma or any undiagnosed skin lesions

Use with caution in patients with history of cardiovascular disease (including myocardial infarction and arrhythmias); pulmonary diseases such as asthma, psychosis, wide-angle glaucoma, peptic ulcer disease; as well as in renal, hepatic, or endocrine disease. Sudden discontinuation of levodopa may cause a worsening of Parkinson's disease. Elderly may be more sensitive to CNS effects of levodopa. May cause or exacerbate dyskinesias. May cause orthostatic hypotension; Parkinson's disease patients appear to have an impaired capacity to respond to a postural challenge. Use with caution in patients at risk of hypotension (such as those receiving antihypertensive drugs) or where transient hypotensive episodes would be poorly tolerated (cardiovascular disease or cerebrovascular disease). Observe patients closely for development of depression with concomitant suicidal tendencies. Safety and effectiveness in pediatric patients have not been established. Some products may contain tartrazine. Dopaminergic agents have been associated with a syndrome resembling neuroleptic malignant syndrome on withdrawal or significant dosage reduction after long-term use. Pyridoxine may reverse effects of levodopa. Toxic reactions have occurred with dextromethorphan.

Cardiovascular: Orthostatic hypotension, arrhythmias, chest pain, hypertension, syncope, palpitations, phlebitis

Central nervous system: Dizziness, anxiety, confusion, nightmares, headache, hallucinations, on-off phenomenon, decreased mental acuity, memory impairment, disorientation, delusions, euphoria, agitation, somnolence, insomnia, gait abnormalities, nervousness, ataxia, EPS, falling

Gastrointestinal: Anorexia, nausea, vomiting, constipation, GI bleeding, duodenal ulcer, diarrhea, dyspepsia, taste alterations, sialorrhea, heartburn

Genitourinary: Discoloration of urine, urinary frequency

Hematologic: Hemolytic anemia, agranulocytosis, thrombocytopenia, leukopenia, decreased hemoglobin and hematocrit, abnormalities in AST and ALT, LDH, bilirubin, BUN, Coombs' test

Neuromuscular & skeletal: Choreiform and involuntary movements, paresthesia, bone pain, shoulder pain, muscle cramps, weakness

Ocular: Blepharospasm

Renal: Difficult urination

Respiratory: Dyspnea, cough

Miscellaneous: Hiccups, discoloration of sweat

Symptoms of overdose include palpitations, dysrhythmias, spasms, hypertension

Use fluids judiciously to maintain pressures; may precipitate a variety of arrhythmias

Benzodiazepines may inhibit the antiparkinsonian effects of levodopa; monitor for reduced effect

Antipsychotics may inhibit the antiparkinsonian effects of levodopa via dopamine receptor blockade; use antipsychotics with low dopamine blockade (clozapine, olanzapine, quetiapine)

High-protein diets may inhibit levodopa's efficacy; avoid high protein diets

Iron binds levodopa and reduces its bioavailability; separate doses of iron and levodopa

Concurrent use of levodopa with nonselective MAOIs may result in hypertensive reactions via an increased storage and release of dopamine, norepinephrine, or both. Use with carbidopa to minimize reactions if combination is necessary; otherwise avoid combination.

L-methionine, phenytoin, pyridoxine, and spiramycin may inhibit levodopa's antiparkinsonian effects

Tacrine may inhibit the effects of levodopa via enhanced cholinergic activity; monitor

Increases dopamine levels in the brain, then stimulates dopaminergic receptors in the basal ganglia to improve the balance between cholinergic and dopaminergic activity

Duration: Variable, usually 6-12 hours

Time to peak serum concentration: Oral: 1-2 hours

Metabolism: Majority of drug is peripherally decarboxylated to dopamine; small amounts of levodopa reach the brain where it is also decarboxylated to active dopamine

Half-life: 1.2-2.3 hours

Elimination: Primarily in urine (80%) as dopamine, norepinephrine, and homovanillic acid

Oral:

0.5 g/m² or

<30 lb: 125 mg

30-70 lb: 250 mg

>70 lb: 500 mg

Adults: 500-1000 mg/day in divided doses every 6-12 hours; increase by 100-750 mg/day every 3-7 days until response or total dose of 8000 mg is reached

A significant therapeutic response may not be obtained for 6 months

High protein diets may decrease the efficacy of levodopa when used for parkinsonism via competition with amino acids in crossing the blood-brain barrier.

Serum growth hormone concentration

False-positive reaction for urinary glucose with Clinitest®; false-negative reaction using Clinistix®; false-positive urine ketones with Acetest®, Ketostix®, Labstix®

No information available to require special precautions

Dopaminergic therapy in Parkinson's disease (ie, treatment with levodopa) is associated with orthostatic hypotension. Patients medicated with levodopa should be carefully assisted from the chair and observed for signs of orthostatic hypotension.

Take exactly as directed; do not change dosage or discontinue without consulting prescriber. Therapeutic effects may take several weeks or months to achieve and you may need frequent monitoring during first weeks of therapy. Take with meals if GI upset occurs, before meals if dry mouth occurs, after eating if drooling or if nausea occurs. Take at the same time each day. Maintain adequate hydration (2-3 L/day of fluids unless instructed to restrict fluid intake); void before taking medication. Do not use alcohol and prescription or OTC sedatives or CNS depressants without consulting prescriber. Urine or perspiration may appear darker. You may experience drowsiness, dizziness, confusion, or vision changes (use caution when driving, climbing stairs, or engaging in tasks requiring alertness until response to drug is known); orthostatic hypotension (use caution when changing position - rising to standing from sitting or lying); increased susceptibility to heat stroke, decreased perspiration (use caution in hot weather - maintain adequate fluids and reduce exercise activity); constipation (increased exercise, fluids, or dietary fruit and fiber may help); dry skin or nasal passages (consult prescriber for appropriate relief); nausea, vomiting, loss of appetite, or stomach discomfort (small frequent meals, frequent mouth care, chewing gum, or sucking lozenges may help). Report unresolved constipation or vomiting; chest pain or irregular heartbeat; difficulty breathing; acute headache or dizziness; CNS changes (hallucination, loss of memory, nervousness, etc); painful or difficult urination; abdominal pain or blood in stool; increased muscle spasticity or rigidity; skin rash; or significant worsening of condition. Pregnancy/breast-feeding precautions: Inform prescriber if you are or intend to be pregnant. Consult prescriber if breast-feeding.

Sustained release product should not be crushed

Capsule: 100 mg, 250 mg, 500 mg

Tablet: 100 mg, 250 mg, 500 mg

Cara JF and Johanson HJ, "Growth Hormone for Short Stature Not Due to Classic Growth Hormone Deficiency," Pediatr Clin North Am, 1990, 37(6):1229-54.

Hoehn MM and Rutledge CO, "Acute Overdose With Levodopa: Clinical and Biochemical Consequences," Neurology, 1975, 25(8):792-4.

Nutt JG and Fellman JH, "Pharmacokinetics of Levodopa," Clin Neuropharmacol, 1984, 7(1):35-49.

Sporer KA, "Carbidopa-Levodopa Overdose," Am J Emerg Med, 1991, 9(1):47-8.