Methyprylon (Systemic)
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VA CLASSIFICATION
Primary: CN309
Note: For a listing of dosage forms and brand names by country availability, see Dosage Forms section(s).
*Not commercially available in the U.S.
†Not commercially available in Canada.
Category:
Sedative-hypnotic—
Indications
Accepted
—Methyprylon has been used for the treatment of insomnia. {06} However, this medication generally has been replaced by other sedative-hypnotic agents for the treatment of insomnia.
—Methyprylon has been shown to be effective for at least 7 consecutive nights. If this medication is used for the treatment of insomnia, prolonged use of methyprylon is generally not recommended. {04} {05} {06}
Pharmacology/Pharmacokinetics
Physicochemical characteristics:
Molecular weight—
183.25
Mechanism of action/Effect:
The precise mechanism of action has not been fully determined; however, in animal studies, methyprylon has been shown to increase the threshold of arousal centers in the brain stem. {05}
Protein binding:
Plasma—Moderate (60%). {05} {06}
Biotransformation:
Hepatic. Methyprylon is almost completely metabolized. {05} {06}
Half-life:
Plasma half-life is 6 to 16 hours.
Onset of action:
Within 45 minutes. {05} {06}
Duration of action:
5 to 8 hours. {05} {06}
Elimination:
Renal; less than 1% of a dose is excreted unchanged. {05} {06}
Precautions to Consider
Carcinogenicity/Mutagenicity
Studies to determine the carcinogenic or mutagenic potential of methyprylon have not been done. {03} {06}
Pregnancy/Reproduction
Fertility—
Studies in rats showed that methyprylon, administered at doses of 5 and 50 mg per kg of body weight (mg/kg) per day, had no adverse effects on reproduction. {05} {06}
Pregnancy—
Adequate and well-controlled studies in humans have not been done. However, studies in animals (rats and rabbits) at doses up to approximately 9 times the maximum recommended human dose (MRHD) have not shown that methyprylon causes teratogenic effects on the fetus (FDA Pregnancy Category B). {05} {06}
Breast-feeding
It is not known whether methyprylon is excreted in breast milk. However, problems in humans have not been documented. {05} {06}
Pediatrics
Appropriate studies have not been performed in children up to 12 years of age. {05} {06} Safety and efficacy have not been established.
Geriatrics
Elderly patients may be more sensitive to the effects of methyprylon. In addition, elderly patients are more likely to have age-related renal function impairment, which may require reduction of dosage in patients receiving methyprylon.
Drug interactions and/or related problems
The following drug interactions and/or related problems have been selected on the basis of their potential clinical significance (possible mechanism in parentheses where appropriate)—not necessarily inclusive (» = major clinical significance):
Note: Combinations containing any of the following medications, depending on the amount present, may also interact with this medication.
Addictive medications, other, especially central nervous system (CNS) depressants with habituating potential (prolonged concurrent use may increase the risk of habituation; caution is recommended)
» Alcohol or
» CNS depression–producing medications, other (See Appendix II ) (concurrent use may increase the CNS depressant effects of either these medications or methyprylon; caution is recommended and dosage of one or both agents should be reduced {04} {05} {06})
Laboratory value alterations
The following have been selected on the basis of their potential clinical significance (possible effect in parentheses where appropriate)—not necessarily inclusive (» = major clinical significance):
With diagnostic test results
Urinary steroid determinations (methyprylon may interfere with the absorbance of both urinary 17-ketosteroids, using the Holtorff Koch modification of the Zimmerman reaction, and 17-hydroxycorticosteroids, using the modified Glenn-Nelson technique)
Medical considerations/Contraindications
The medical considerations/contraindications included have been selected on the basis of their potential clinical significance (reasons given in parentheses where appropriate)— not necessarily inclusive (» = major clinical significance).
Risk-benefit should be considered when the following medical problems exist
» Drug abuse or dependence, history of (predisposition of patients to habituation and dependence {03})
Hepatic function impairment (methyprylon metabolized in liver {05} {06})
Porphyria, intermittent (condition may be exacerbated {03} {05} {06})
Renal function impairment (methyprylon excreted via kidneys {05} {06})
Sensitivity to methyprylon{05}{06}
Patient monitoring
The following may be especially important in patient monitoring (other tests may be warranted in some patients, depending on condition; » = major clinical significance):
Blood cell counts (may be required at periodic intervals for patients on prolonged therapy {05} {06})
Side/Adverse Effects
The following side/adverse effects have been selected on the basis of their potential clinical significance (possible signs and symptoms in parentheses where appropriate)—not necessarily inclusive:
Those indicating need for medical attention
Incidence less frequent
Allergic reaction (skin rash or itching)
paradoxical reaction (unusual excitement)
Incidence rare
Fever, unexplained
mental depression
neutropenia (ulcers or sores in mouth or throat)
thrombocytopenia (unusual bleeding or bruising)
{05}{06}
Those indicating need for medical attention only if they continue or are bothersome
Incidence more frequent
Dizziness
drowsiness, daytime, mild
headache
Incidence less frequent or rare
Blurred or double vision
clumsiness or unsteadiness
constipation
diarrhea
nausea
unusual weakness
vomiting
{05}{06}
Those indicating possible withdrawal and the need for medical attention if they occur after medication is discontinued
Confusion
convulsions
hallucinations
increased dreaming
increased sweating
nausea or vomiting
nightmares
restlessness or nervousness
stomach cramps
trembling
trouble in sleeping
unusual weakness
{05}{06}
Overdose
For specific information on the agents used in the management of methyprylon overdose, see:
• Barbiturates (Systemic) monograph; or
• Metaraminol in Sympathomimetic Agents—Cardiovascular Use (Parenteral-Systemic) monograph; and/or
• Norepinephrine in Sympathomimetic Agents—Cardiovascular Use (Parenteral-Systemic) monograph.
For more information on the management of overdose or unintentional ingestion, contact a Poison Control Center (see Poison Control Center Listing ).
Clinical effects of overdose
The following effects have been selected on the basis of their potential clinical significance (possible signs and symptoms in parentheses where appropriate)–not necessarily inclusive:
Symptoms of overdose
Confusion
drowsiness, severe
fast heartbeat
shortness of breath or slow or troubled breathing
staggering
swelling of feet or lower legs
weakness, severe
Note: Excitation and convulsions have been reported in patients following methyprylon overdose, especially during the recovery phase.
{05}{06}
Treatment of overdose
Recommended treatment of methyprylon overdose includes the following: {05} {06}
To decrease absorption:
Immediate gastric lavage with precautions to prevent pulmonary aspiration.
Specific treatment:
Controlling hypotension with norepinephrine, metaraminol, or other antihypotensive measures. If excitation and convulsions occur, using barbiturates but with great caution.
Hemodialysis may be beneficial; therefore, its use should be considered, especially in those patients where supportive measures are failing and adequate urinary output cannot be maintained.
Monitoring:
Monitoring respiration, pulse, and blood pressure.
Supportive care:
Using general supportive measures, along with administering appropriate intravenous fluids and maintaining an adequate airway.
Patients in whom intentional overdose is known or suspected should be referred for psychiatric consultation.
Patient Consultation
As an aid to patient consultation, refer to Advice for the Patient, Methyprylon (Systemic).
In providing consultation, consider emphasizing the following selected information (» = major clinical significance):
Before using this medication
» Conditions affecting use, especially:
Sensitivity to methyprylon
Use in the elderly—Elderly patients may be more sensitive to effects of methyprylon
Other medications, especially alcohol or other CNS depression–producing medications
Other medical problems, especially history of drug abuse or dependence
Proper use of this medication
» Importance of not using more medication than the amount prescribed because of habit-forming potential
» Proper storage
Precautions while using this medication
Regular visits to physician to check progress during prolonged therapy
Checking with physician before discontinuing medication after prolonged use; gradual dosage reduction may be necessary to avoid possibility of withdrawal symptoms
» Avoiding use of alcohol or other CNS depressants
» Suspected overdose: Getting emergency help at once
» Caution if dizziness or daytime drowsiness occurs
Side/adverse effects
Signs of potential side effects, especially allergic reaction, unexplained fever, mental depression, neutropenia, paradoxical reaction, and thrombocytopenia
Side/adverse effects more likely to occur in elderly patients, who may be more sensitive to effects of methyprylon
General Dosing Information
Prolonged use of larger than usual therapeutic doses may result in psychic or physical dependence. {05}
Following prolonged administration, methyprylon should be withdrawn gradually in order to avoid the possibility of precipitating withdrawal symptoms. {05}
For treatment of dependence
Treatment of physical dependence consists of cautious and gradual withdrawal of methyprylon or substitution of a barbiturate, such as phenobarbital, which is then gradually withdrawn. {05}
Oral Dosage Forms
METHYPRYLON CAPSULES USP
Usual adult dose
Sedative-hypnotic—Oral, 300 mg at bedtime. {04} {05} {06}
Note: Geriatric or debilitated patients may be more sensitive to the effects of the usual adult dose.
Usual pediatric dose
Sedative-hypnotic
Children up to 12 years of age: Safety and efficacy have not been established. {03} {05} {06}
Children 12 years of age and over: Dosage must be individualized. {05} {06}
Strength(s) usually available
Note: Withdrawn from the U.S. market in June 1965 and the Canadian market in September 1990.
U.S.—
Not commercially available.
Canada—
Not commercially available.
Packaging and storage:
Store below 40 °C (104 °F), preferably between 15 and 30 °C (59 and 86 °F), unless otherwise specified by manufacturer. Store in a tight, light-resistant container.
Auxiliary labeling:
• Avoid alcoholic beverages.
• May cause drowsiness.
Note: Controlled substance in the U.S.
METHYPRYLON TABLETS USP
Note: Methyprylon tablets are not commercially available in Canada.
Usual adult dose
Sedative-hypnotic
Oral, 200 to 400 mg at bedtime. {05}
Note: Geriatric or debilitated patients may be more sensitive to the effects of the usual adult dose.
Usual pediatric dose
Sedative-hypnotic
Children up to 12 years of age: Safety and efficacy have not been established. {03} {05}
Children 12 years of age and over: Dosage must be individualized. {05} {06}
Strength(s) usually available
U.S.—
Not commercially available.
Canada—
Not commercially available.
Packaging and storage:
Store below 40 °C (104 °F), preferably between 15 and 30 °C (59 and 86 °F), unless otherwise specified by manufacturer. Store in a tight, light-resistant container.
Auxiliary labeling:
• Avoid alcoholic beverages.
• May cause drowsiness.
Note: Controlled substance in the U.S.
Revised: 10/13/2000
References
- USAN 1986.
- USP/NF 1985.
- PDR 1986: 1495.
- CPS 1988, Noludar (Roche, Canada): 613.
- PDR 1988, Noludar (Roche): 1733.
- PDR 1989 (Roche): 1742.
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