Selegiline

INTRODUCTION

Indications

Management of Parkinson's disease (with levodopa or levodopa/carbidopa) in patients who fail to respond to levodopa/carbidopa alone.

Action

Following conversion by MAO to its active form, selegiline inactivates MAO by irreversibly binding to it at type B (brain) sites. Inactivation of MAO leads to increased amounts of dopamine available in the CNS. Therapeutic Effects: Increased response to levodopa/dopamine therapy in Parkinson's disease.

Adverse Reactions/Side Effects

CNS: confusion, dizziness, fainting, hallucinations, insomnia, vivid dreams. GI: nausea, abdominal pain, dry mouth.

PHYSICAL THERAPY IMPLICATIONS

Examination and Evaluation

• Assess gait and motor function to help determine antiparkinson effects, especially when starting drug therapy, or during dosing changes or addition of other antiparkinson drugs. Motor function should be assessed at different times of the day, such as when drugs are reaching peak therapeutic levels (i.e., 30–60 min after oral dose), as well as when drug effects are minimal (just before the next dose).

• Document increased motor side effects such as involuntary movements (dyskinesias), fluctuations in response (on-off phenomenon, end-of-dose akinesia), or other abnormal movement patterns. Notify physician because increased motor side effects might require dose adjustment or a change in medication regimen.

• Monitor confusion, hallucinations, and other psychologic problems. Repeated or excessive symptoms may require change in dose or medication.

• Assess dizziness and fainting that affects gait, balance, and other functional activities (see Appendix C). Report balance problems and functional limitations to the physician, and caution the patient and family/caregivers to guard against falls and trauma.

Interventions

• Implement therapeutic exercises (coordination exercises, gait training, cardiovascular conditioning) to complement the effects of drug therapy and help achieve optimal function.

• Guard against falls and trauma (hip fractures, head injury, and so forth). Implement fall-prevention strategies (See Appendix E), especially if patient exhibits Parkinson's symptoms (postural instability, rigidity) combined with drug side effects (dizziness, fainting).

Patient/Client-Related Instruction

• Advise patient to avoid alcohol because of the increased risk of sedation and adverse effects.

• Instruct patient to report other troublesome side effects such as severe or prolonged sleep loss, vivid dreams, or GI reactions (nausea, abdominal pain, dry mouth).

Pharmacokinetics

Absorption: Appears to be well absorbed following oral administration.

Distribution: Widely distributed.

Metabolism and Excretion: Metabolism involves some conversion to amphetamine and methamphetamine. 45% excreted in urine as metabolites.

Half-life: Unknown; orally disintegrating tablets 1.3 hr.