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Side Effects


The following adverse reactions are discussed in more detail in the WARNINGS AND PRECAUTIONS section of labeling.

Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, the incidence of adverse reactions (number of unique patients experiencing an adverse reaction per total number of patients treated) observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the incidence of adverse reactions observed in clinical practice.

Because the controlled trials performed during premarketing development both used a titration design (1.25 mg per day for 6 weeks, followed by 2.5 mg per day for 6 weeks), with a resultant confounding of time and dose, it was impossible to adequately evaluate the effects of dose on the incidence of adverse events.

The most common adverse reactions (treatment difference incidence at least 3% greater than placebo incidence) reported in the double-blind, placebo-controlled trials during ZELAPAR treatment were constipation, skin disorders, vomiting, dizziness, dyskinesia, insomnia, dyspnea, myalgia, and rash (See Table 1).

Of the 194 patients treated with ZELAPAR in the double-blind, placebo-controlled trials, 5% discontinued due to adverse reactions compared to 1% of the 98 patients who received placebo. Most common adverse reactions causing discontinuation of treatment included dizziness, chest pain, accidental injury, and myasthenia.

Incidence In Controlled Clinical Trials

Table 1 lists the adverse events reported in the placebo-controlled trials after at least one dose of ZELAPAR (incidence 2% or greater).

Table 1: Treatment-Emergent Adverse Events* Incidence in Double-Blind, Placebo-Controlled Trials (Events ≥ 2% of Patients Treated with ZELAPAR and Numerically More Frequent than the Placebo Group)

Body System/ Adverse Event ZELAPAR† 1.25/2.5 mg
N=194 %
Placebo †
N=98 %
Body as a Whole
Back Pain 5 3
Chest Pain 2 0
Pain 8 7
Cardiovascular System
Hypertension 3 2
Digestive System
Constipation 4 0
Diarrhea 2 1
Dysphagia 2 1
Dyspepsia 5 3
Flatulence 2 1
Nausea 11 9
Stomatitis 5 4
Tooth Disorder 2 1
Vomiting 3 0
Hemic and Lymphatic System
Ecchymosis 2 0
Metabolic and Nutritional Disorders
Hypokalemia 2 0
Musculoskeletal System
Leg Cramps 3 1
Myalgia 3 0
Nervous System
Ataxia 3 1
Depression 2 1
Dizziness 11 8
Dry Mouth 4 2
Dyskinesia 6 3
Hallucinations 4 2
Headache 7 6
Insomnia 7 4
Somnolence 3 2
Tremor 3 1
Respiratory System
Dyspnea 3 0
Pharyngitis 4 2
Rhinitis 7 6
Skin and Appendages
Rash 4 1
Skin Disorders** 6 2
* Patients may have reported multiple adverse experiences during the study or at discontinuation; thus patients may be included in more than one category.
** Skin disorders represent any new skin abnormality that would not be characterized as rash or neoplastic lesion. These include events such as skin ulcer, fungal dermatitis, skin hypertrophy, contact dermatitis, herpes simplex, dry skin, sweating, urticaria, and pruritus.
† Patients received concomitant levodopa.

Treatment-emergent adverse reactions for certain events were reported at a higher frequency by patients ≥ 65 years of age compared to patients < 65 years [see Use in Specific Populations].

No consistent differences in the incidences of adverse reactions were observed between male and female patients.

There were insufficient data to assess the impact of race on the incidence of adverse reactions.

Read the Zelapar (selegiline hydrochloride) Side Effects Center for a complete guide to possible side effects



Serious, sometimes fatal reactions have been reported in patients treated with concomitant meperidine (e.g., Demerol and other tradenames) and MAO inhibitors including selective MAO-B inhibitors [see CONTRAINDICATIONS].


The combination of MAO inhibitors and dextromethorphan has been reported to cause brief episodes of psychosis or bizarre behavior. Therefore, in view of ZELAPAR's MAO inhibitory activity, dextromethorphan should not be used concomitantly with ZELAPAR [see CONTRAINDICATIONS].

MAO Inhibitors

ZELAPAR should not be administered along with other selegiline products (e.g., EMSAM or ELDEPRYL®) because of the increased risk of non-selective MAO inhibition that may lead to a hypertensive crisis [see CONTRAINDICATIONS].

Sympathomimetic Medications

Uncontrolled hypertension, including hypertensive crisis, has been reported when taking the recommended dose of swallowed selegiline and a sympathomimetic medication (ephedrine).

Tyramine/Selegiline Interaction

The enzyme, monoamine oxidase (MAO) (primarily type A), in the gastrointestinal tract and liver provides protection from ingested amines (e.g., tyramine) that, if absorbed, have the capacity to cause uncontrolled hypertension (tyramine reaction). If MAO is inhibited in the gastrointestinal tract and liver, ingestion of exogenous amines contained in some foods such as fermented cheese, herring, or over-the-counter cough/cold medicines may be absorbed systemically causing release of norepinephrine and a rise in systemic blood pressure with the potential for uncontrolled hypertension. Selective MAO-B inhibitors lose their selectivity for MAO-B when taken in doses higher than recommended. Nonselective MAO-A inhibitors or MAO-B inhibitors in higher than recommended doses may result in MAO-A inhibition in the gastrointestinal tract and liver.

Results of a tyramine challenge study indicate that ZELAPAR is relatively selective for MAO-B at the recommended dose. In most cases, there is no need for dietary tyramine restriction in patients prescribed ZELAPAR [see CLINICAL PHARMACOLOGY] at the recommended dose. Because the selectivity for inhibiting MAO-B diminishes as the dose of ZELAPAR is increased above the recommended daily dose, patients should not take more than 2.5 mg of ZELAPAR daily.

Reports of hypertensive reactions have occurred in patients who ingested tyraminecontaining consumables (i.e., food or drink) while receiving swallowed selegiline at the recommended dose (a dose believed to be relatively selective for MAO-B). Hypertensive crisis has also been reported with ZELAPAR use that was not above the recommended dosing.

Uncontrolled hypertension has been reported when taking the recommended dose of swallowed selegiline and a sympathomimetic medication (ephedrine).

Tricyclic Antidepressants And Selective Serotonin Reuptake Inhibitors

Severe toxicity has also been reported in patients receiving the combination of tricyclic antidepressants and swallowed selegiline, or selective serotonin reuptake inhibitors and swallowed selegiline [see WARNINGS AND PRECAUTIONS].

Drugs That Induce CYP450

Adequate studies have not been done investigating the effect of CYP3A4-inducers on selegiline. Drugs that induce CYP3A4 (e.g., phenytoin, carbamazepine, nafcillin, phenobarbital, and rifampin) should be used with caution.

Dopaminergic Antagonists

It is possible that dopamine antagonists, such as antipsychotics or metoclopramide, could diminish the effectiveness of ZELAPAR.

Read the Zelapar Drug Interactions Center for a complete guide to possible interactions

This monograph has been modified to include the generic and brand name in many instances.

Last reviewed on RxList: 9/29/2014

Side Effects

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You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.

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