Methadone Hydrochloride Side Effects

ADVERSE REACTIONS The following serious adverse reactions are described, or described in greater detail, in other sections: • Addiction, Abuse, and Misuse (see WARNINGS ) • Life Threatening Respiratory Depression (see WARNINGS ) • QT Prolongation (see WARNINGS ) • Neonatal Opioid Withdrawal Syndrome (see WARNINGS ) • Interactions with CNS Depressants (see WARNINGS ) • Serotonin Syndrome (see WARNINGS ) • Adrenal Insufficiency (see WARNINGS ) • Severe Hypotension (see WARNINGS ) • Gastrointestinal Adverse Reactions (see WARNINGS ) • Seizures (see WARNINGS ) • Withdrawal (see WARNINGS ) • Hypoglycemia (see WARNINGS ) The following adverse reactions associated with the use of methadone were identified in clinical studies or post-marketing reports.

Because some of these reactions were reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

The major hazards of methadone are respiratory depression and, to a lesser degree, systemic hypotension.

Respiratory arrest, shock, cardiac arrest, and death have occurred.

The most frequently observed adverse reactions include lightheadedness, dizziness, sedation, nausea, vomiting, and sweating.

These effects seem to be more prominent in ambulatory patients and in those who are not suffering severe pain.

In such individuals, lower doses of methadone are advisable.

Other adverse reactions that have been reported in patients (including opioid addicts taking methadone for detoxification or maintenance) receiving methadone include the following: Body as a Whole : asthenia (weakness), edema, headache Cardiovascular: Arrhythmias, bigeminal rhythms, bradycardia, extrasystoles, tachycardia, Torsade de Pointes, ventricular fibrillation, ventricular tachycardia.

ECG abnormalities, prolonged QT interval, T-wave inversion, cardiomyopathy, flushing, heart failure, hypotension, palpitations, phlebitis, syncope Digestive: Abdominal pain, anorexia, biliary tract spasm, constipation, dry mouth, glossitis Hematologic and Lymphatic: Reversible thrombocytopenia has been described in opioid addicts with chronic hepatitis.

Metabolic and Nutritional: Hypokalemia, hypomagnesemia, weight gain Central Nervous System: Agitation, confusion, seizures, disorientation, dysphoria, euphoria, insomnia, hallucinations, seizures, visual disturbances, congenital oculomotor disorders (nystagmus, strabismus) Respiratory: Pulmonary edema Skin and Appendages: Intramuscular and Subcutaneous: Local tissue reactions (pain, erythema, swelling), particularly with continuous subcutaneous infusion Intravenous: Pruritis, urticaria, other skin rashes, and rarely, hemorrhagic urticaria Special Senses: Visual disturbances Urogenital: Antidiuretic effect, amenorrhea, urinary retention or hesitancy, reduced libido and/or potency Serotonin Syndrome : Cases of serotonin syndrome, a potentially life-threatening condition, have been reported during concomitant use of opioids with serotonergic drugs.