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Methadone
Each tablet for Oral administration contains: Methadone Hydrochloride................. 5 mg, 10 mg (Warning: May be habit forming) Inactive Ingredients: The tablets contain magnesium stearate, microcrystalline cellulose, and starch (com), Chemically, methadone hydrochloride is 3-Heptan-One, 6-(dimethylamino-4,4-diphenyl-, hydrochloride. Methadone hydrochloride
acts as a narcotic
analgesic.
Methadone hydrochloride is a synthetic narcotic analgesic with multiple actions quantitatively similar to those at morphine, the most prominent of which involve the central nervous system and organs composed of smooth muscle. The principal actions of therapeutic value are analgesia and sedation and detoxification or temporary maintenance in narcotic addiction. The methadone abstinence syndrome, although qualitatively similar to that of morphine, differs in that the onset is slower, the course is more prolonged, and the symptoms are less severe. When administered orally, methadone is approximately one-half as
potent as when given parenterally. Oral administration
results in a delay of the onset, a lowering of the peak, and an
increase in the duration
of analgesic effect.
Methadone hydrochloride is indicated for relief of severe pain, for detoxification treatment of narcotic addiction, and for temporary maintenance treatment of narcotic addiction.
For Relief of Severe Pain Dosage should be adjusted according to the severity of the pain and the response of the patient. Occasionally it may be necessary to exceed the usual dosage recommended in cases of exceptionally severe pain or in those patients who have become tolerant to the analgesic effects of narcotics. The usual adult dosage is 2.5 mg to 10 mg every three or four hours as necessary. For Detoxification Treatment THE DRUG SHALL BE ADMINISTERED DAILY UNDER CLOSE SUPERVISION AS FOLLOWS: A detoxification treatment course shall not exceed 21 days and may not be repeated earlier than four weeks after completion of the preceding course. The oral form of administration is preferred. However, if the patient is unable to ingest oral medication, he may be started on the parenteral form initially. In detoxification, the patient may receive methadone when there are significant symptoms of withdrawal. The dosage schedules indicated below are recommended but could be varied in accordance with clinical judgment. Initially, a single oral dose of 15 to 20 mg of methadone will often be sufficient to suppress withdrawal symptoms. Additional methadone may be provided if withdrawal symptoms are not suppressed or if symptoms reappear. When patients are physically dependent on high doses, it maybe necessary to exceed these levels. Forty mg per day in single or divided doses will usually constitute an adequate stabilizing dosage level. Stabilization can be continued for two to three days, and then the amount of methadone normally will be gradually decreased. The rate at which methadone is decreased will be determined separately with each patient. The dose of methadone ran be decreased on a daily basis or at two-day intervals, but the amount of intake shall always be sufficient to keep withdrawal symptoms at a tolerable level. In hospitalized patients, a daily reduction of 20 percent of the total daily dose maybe tolerated and may cause little discomfort. In ambulatory patients, a somewhat slower schedule may be needed. If methadone is administered for more than three weeks, the procedure is considered to have progressed from detoxification or treatment of the acute withdrawal syndrome to maintenance treatment, even though the goal and intent may be eventual total with-drawal. HOW SUPPLIED Methadone Hydrochloride Tablets USP Dispense in a well-closed container as defined in the USP/NF. Store at Controlled Room Temperature 15°-30°C (59°-86°F) Caution: Federal law
prohibits dispensing without prescription.
THE MAJOR HAZARDS OF METHADONE AS OF OTHER NARCOTIC ANALGESICS, ARE RESPIRATORY DEPRESSION AND TO A LESSER DEGREE, CIRCULATORY DEPRESSION. RESPIRATORY ARREST SHOCK, AND CARDIAC ARREST 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 chronic pain. In such individuals, lower doses are advisable. Some adverse reactions may be alleviated in the ambulatory patient if he lies down. Other adverse reactions include the following:
Interaction with Pentazocine Patients who are addicted to heroin or who are on the methadone maintenance program may experience withdrawal symptoms when given pentazocine. Interaction with Rifampin The concurrent administration of rifampin may possibly reduce the blood concentration of methadone. The mechanism by which rifampin may decrease blood concentrations of methadone is not fully understood although enhanced microsomal drug-metabolized enzymes may influence drug disposition. Interaction with Monoamine Oxidase (MAO) Inhibitors Therapeutic doses of meperidine have precipitated severe reactions in patients concurrently receiving monoamine oxidase inhibitors or those who have received such agents within 14 days. Similar reactions thus far have not been reported with methadone; but if the use of methadone is necessary in such patients, a sensitivity test should be performed in which repeated small incremental doses are administered over the course of several hours while the patient's condition and vital signs are under careful observation. Interaction with Other Central-Nervous-Systern Depressants Methadone should be used with caution and in reduced dosage
in patients who are concurrently receiving other narcotic
analgesics, general anesthetics, phenothiazines, other tranquilizers,
sedative-hypnotics, tricyclic antidepressants, and other CNS
depressants (including alcohol). Respiratory depression, hypotension,
and profound sedation
or coma may result.
DRUG DEPENDENCE-METHADONE CAN PRODUCE DRUG DEPENDENCE OF THE MORPHINE TYPE AND, THEREFORE HAS THE POTENTIAL FOR BEING ABUSED. PSYCHIC DEPENDENCE, PHYSICAL DEPENDENCE AND TOLERANCE MAY DEVELOP UP ON REPEATED ADMINISTRATION OF METHADONE AND IT SHOULD BE PRESCRIBED AND ADMINISTERED WITH THE SAME DEGREE OF CAUTION APPROPRIATE TO THE USE OF MORPHINE. Interaction with Other Central-Nervous-System Depressants Methadone should be used with caution and in reduced dosage in patients who are concurrently receiving other narcotic analgesics, general anesthetics, phenothiazines, other tranquilizers, sedative-hypnotics, tricyclic antidepressants, and other CNS depressants (including alcohol). Respiratory depression, hypotension, and profound sedation or coma may result. Anxiety Since methadone, as used by tolerant subjects at a constant maintenance dosage, is not a tranquilizer, patients who are maintained on this drug will react to life problems and stresses with the same symptoms of anxiety as do other individuals. The physician should not confuse such symptoms with those of narcotic abstinence and should not attempt to treat anxiety by increasing the dosage of methadone. The action of methadone in maintenance treatment is limited to the control of narcotic symptoms and is ineffective for relief of general anxiety. Head injury and increased Intracranial Pressure The respiratory depressant effects of methadone and its capacity to elevate cerebrospinal-fluid pressure may be markedly exaggerated in the presence of increased intracranial pressure. Furthermore, narcotics produce side effects that may obscure the clinical course of patients with head injuries. In such patients, methadone must be used with caution and only if it is deemed essential. Asthma and Other Respiratory Conditions Methadone should be used with caution in patients having an acute asthmatic attack, in those with chronic obstructive pulmonary disease or cor pulmonale, and in individuals with a substantially decreased respiratory reserve, preexisting respiratory depression, hypoxia, or hypercapnia. In such patients, even usual therapeutic doses of narcotics may decrease respiratory drive while simultaneously increasing airway resistance to the point of apnea. Hypotensive Effect The administration of methadone may result in severe hypotension in an individual whose ability to maintain his blood pressure has already been compromised by a depleted blood volume or concurrent administration of such drugs as the phenothiazines or certain anesthetics. Use in Ambulatory Patients Methadone may impair the mental and/or physical abilities required for the performance of potentially hazardous tasks, such as driving a car or operating machinery. The patient should be cautioned accordingly. Methadone, like other narcotics, may produce ortho-static hypotension in ambulatory patients. Use in Pregnancy Safe use in pregnancy has not been established in relation to possible adverse effects on fetal development. Therefore, methadone should not be used in pregnant women unless, in the judgment of the physician, the potential benefits outweigh the possible hazards. Methadone is not recommended for obstetric analgesia because its long duration of action increases the probability of respiratory depression in the newborn. Use in Children Methadone is not recommended for use as an analgesic in children, since documented clinical experience has been insufficient to establish a suitable dosage regimen for the pediatric age group.
Interaction with Pentazocine Patients who are addicted to heroin or who are on the methadone maintenance program may experience withdrawal symptoms when given pentazocine. Interaction with Rifampin The concurrent administration of rifampin may possibly reduce the blood concentration of methadone. The mechanism by which rifampin may decrease blood concentrations of methadone is not fully understood although enhanced microsomal drug-metabolized enzymes may influence drug disposition. Acute Abdominal Conditions The administration of methadone or other narcotics may obscure the diagnosis or clinical course in patients with acute abdominal conditions. Interaction with Monoamine Oxidase (MAO) Inhibitors Therapeutic doses of meperidine have precipitated severe reactions in patients concurrently receiving monoamine oxidase inhibitors or those who have received such agents within 14 days. Similar reactions thus far have not been reported with methadone; but if the use of methadone is necessary in such patients, a sensitivity test should be performed in which repeated small incremental doses are administered over the course of several hours while the patient's condition and vital signs are under careful observation. Special-Risk Patients Methadone should be given with caution and the initial
dose should be reduced
in certain patients, such
as the elderly or debilitated and those with severe impairment
of hepatic or renal
function, hypothyroidism,
Addison's disease, prostatic
hypertrophy, or
urethral stricture.
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