Dopaminergics

Question 1

Parkinson’s Disease

Answer 1

• lack of dopamine
• dopamine and acetylcholine: neurotransmitters responsible for balance, muscle coordination
• when dopamine is depleted, you see and appearance of muscle rigidity, tremors, psychomotor retardation

Question 2

Carbidopa-Levodopa (Sinemet)

Indications and MOA

Answer 2

• used for Parkinson’s
• Levodopa circulates in the plasma to the blood-brain barrier, where it crosses to be converted by enzymes into dopamine
• Carbidopa inhibits peripheral plasma breakdown of Levodopa, thereby increasing availability of Levodopa at the blood-brain barrier
• best efficacy: take on schedule with food
• best for improving motor impairment

Question 3

Carbidopa-Levodopa (Sinemet)

Caution and Contraindications

Answer 3

• avoid in narrow-angle glaucoma
• avoid in patients with major psychiatric disorders
• avoid in patients with malignant melanoma
• caution with patients who have cardiovascular disease
• caution in elderly patients
• risk of neuroleptic malignant syndrome if abruptly stopped

Question 4

Carbidopa-Levodopa (Sinemet)

Adverse Drug Effects

Answer 4

• orthostatic hypotension, somnolence, dizziness, headache, depression, nausea, constipation, dyskinesia, HTN, insomnia, abnormal dreams
• neuroleptic malignant syndrome (rare), peripheral neuropathy (rare)