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Selegiline; Mechanism, Uses, Contraindications, Dosage, Side effects, Interaction

Selegiline is a selective, irreversible inhibitor of Type B monoamine oxidase. It is used in newly diagnosed patients with Parkinson’s disease. It may slow the progression of the clinical disease and delay the requirement for levodopa therapy. It also may be given with levodopa upon the onset of disability. (From AMA Drug Evaluations Annual, 1994, p385) The compound without isomeric designation is Deprenyl.

Selegiline is a Monoamine Oxidase Inhibitor and Monoamine Oxidase Type B Inhibitor. The mechanism of action of selegiline is as a Monoamine Oxidase Inhibitor and Monoamine Oxidase-B Inhibitor.

Selegiline is an inhibitor of monoamine oxidase used in the treatment of depression and as adjunctive therapy in combination with levodopa and carbidopa in the therapy of Parkinson disease. Selegiline has been associated with a low rate of serum enzyme elevations during treatment but has not been linked to instances of clinically apparent acute liver injury.

Mechanism of action of Selegiline

Although the mechanisms for selegiline’s beneficial action in the treatment of Parkinson’s disease are not fully understood, the selective, irreversible inhibition of monoamine oxidase type B (MAO-B) is thought to be of primary importance. MAO-B is involved in the oxidative deamination of dopamine in the brain. Selegiline binds to MAO-B within the nigrostriatal pathways in the central nervous system, thus blocking microsomal metabolism of dopamine and enhancing the dopaminergic activity in the substantial nigra. Selegiline may also increase dopaminergic activity through mechanisms other than inhibition of MAO-B. At higher doses, selegiline can also inhibit monoamine oxidase type A (MAO-A), allowing it to be used for the treatment of depression.

The action of selegiline is thought to be related to its irreversible inhibition of monoamine oxidase type B (MAO B), the major form of the enzyme in the human brain. MAO B, which is involved in the oxidative deamination of dopamine in the brain, is inhibited when selegiline binds covalently and stoichiometrically to the isoalloxazine flavin adenine dinucleotide (FAD) at its active center. Administration of 10 mg of selegiline a day produces almost complete inhibition of MAO B in the brain. Selegiline becomes a nonselective inhibitor of all monoamine oxidase (MAO) at higher doses, possibly at 20 to 40 mg a day. At these doses, tyramine-mediated hypertensive reaction with MAO-A blockade (“cheese reactions”) may occur.

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Indications of Selegiline

Attention Deficit Disorder With Hyperactivity
Depressive Disorder
Parkinson’s Disease
ADHD
Depression
Monotherapy for initial treatment of Parkinson’s disease, as well as an adjunct therapy in patients with a decreased response to levodopa/carbidopa. Also used for the palliative treatment of mild to moderate Alzheimer’s disease and at higher doses, for the treatment of depression.

Contra-Indications of Selegiline

Malignant melanoma
Severe mental disorder with loss of personality & reality
Abnormal movements of facial muscles and tongue
Abnormal heart rhythm
Blood pressure drop upon standing
Liver problems
Kidney disease with the reduction in kidney function
Allergies to monoamine oxidase inhibitors

Side Effects of Selegiline

The most common

Dizziness
Orthostatic hypotension
Xerostomia (dry mouth)
A headache
Fatigue
Skin reactions
Hypotension
Anxiety
Constipation
Sedation (dose-dependent)
Nausea/vomiting
Weight gain/loss
Pain below the ear (from salivary gland)
Erectile dysfunction

More common

Abdominal or stomach pain, discomfort, or tenderness
chills or fever
difficulty with moving
a headache, severe and throbbing
joint or back pain
muscle aching or cramping
muscle pains or stiffness
chest pressure or squeezing pain in the chest
discomfort in arms, shoulders, neck or upper back
excessive sweating
feeling of heaviness, pain, warmth and/or swelling in a leg or in the pelvis
sudden tingling or coldness in an arm or leg
sudden slow or difficult speech
sudden drowsiness or need to sleep
fast breathing
sharp pain when taking a deep breath
fast or slow heartbeat
coughing up blood
rust colored urine
decreased amount of urine

Rare

Anxiety
change in vision
chest pain or tightness
confusion
a cough
Agitation
arm, back, or jaw pain
blurred vision
chest pain or discomfort
convulsions
extra heartbeats
fainting
hallucinations
a headache
irritability
lightheadedness
mood or mental changes
muscle pain or cramps
muscle spasm or jerking of all extremities
nervousness

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Drug Interactions of Selegiline

Selegiline may interact with the following drug, supplements, & may change the efficacy of the drugs

benzodiazepines (e.g., alprazolam, diazepam, lorazepam)
atomoxetine
cyclobenzaprine
dextroamphetamine
levodopa
MAO inhibitors (e.g., phenelzine, tranylcypromine, rasagiline)
beta-agonists (e.g., formoterol, salbutamol, salmeterol)
other beta-blockers (e.g., propranolol, metoprolol)
calcium channel blockers (e.g., amlodipine, diltiazem, nifedipine, verapamil)
carbamazepine
cyclosporine
dexamethasone
diuretics (water pills; e.g., furosemide, hydrochlorothiazide)
duloxetine
lapatinib
levodopa
sympathomimetic medications (e.g., pseudoephedrine, phenylephrine, ephedrine)
tramadol
lidocaine
MAO inhibitors (e.g., phenelzine, moclobemide, )
macrolide antibiotics (e.g., azithromycin, clarithromycin, erythromycin)
nilotinib
nonsteroidal anti-inflammatory drugs (NSAIDs; e.g., ibuprofen, naproxen)
pentoxifylline
phosphodiesterase-5-inhibitors (e.g., sildenafil, tadalafil)
selective serotonin reuptake inhibitors (SSRI; e.g., fluoxetine, paroxetine, sertraline)
tricyclic antidepressants (e.g., amitriptyline, doxepin, nortriptyline)

Pregnancy Catagory

FDA Pregnancy Category C

Pregnancy

This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Lactation

It is not known if selegiline passes into breast milk. If you are a breastfeeding mother and are taking this medication, it may affect your baby. Talk to your doctor about whether you should continue breastfeeding. The safety and effectiveness of using this medication have not been established for children.