|Systematic (IUPAC) name|
|Metabolism||Rapidly demethylated in the body followed by hydroxylation.|
|Excretion||Via urine (as unchanged and metabolites); more rapid in acidic urine.|
|Molecular mass||163.259 g/mol|
|(what is this?)|
Mephentermine is a cardiac stimulant. It was formerly used in Wyamine nasal decongestant inhalers and before that as a stimulant in psychiatry.
ATC Classification: C01CA11 - mephentermine ; Belongs to the class of adrenergic and dopaminergic cardiac stimulants excluding glycosides. Used in the treatment of heart failure.
Mechanism of Action
Mephentermine appears to act by indirect stimulation of β-adrenergic receptors causing the release of norepinephrine from its storage sites. It has a positive inotropic effect on the myocardium. AV conduction and refractory period of AV node is shortened with an increase in ventricular conduction velocity. It dilates arteries and arterioles in the skeletal muscle and mesenteric vascular beds, leading to an increase in venous return.
Onset: 5-15 minutes (IM), immediate (IV).
Duration: 4 hr (IM), 30 minutes (IV).
Indication & Dosage
Maintenance of blood pressure in hypotensive states Adult: 30-45 mg as a single dose, repeated as necessary or followed by IV infusion of 0.1% mephentermine in 5% dextrose, rate and duration of administration will depend on patient's response.
Hypotension secondary to spinal anaesthesia in obstetric patients Adult: 15 mg as a single dose, repeat if needed.
Hypotension caused by phenothiazines. Hypertension. Pheochromocytoma.
Patient on MAOIs. For shock due to loss of blood or fluid, give fluid replacement therapy primarily, CVS disease, hypertension, hyperthyroidism, chronic illnesses. Lactation, pregnancy.
Adverse Drug Reactions
Drowsiness, incoherence, hallucinations, convulsions, tachycardia. Fear, anxiety, restlessness, tremor, insomnia, confusion, irritability and psychosis. Nausea, vomiting, reduced appetite, urinary retention, dyspnoea, weakness.
Potentially Fatal: AV block, CNS stimulation. Cerebral haemorrhage and pulmonary oedema, ventricular arrhythmias.
Antagonises effect of hypotensive agents. Severe hypertension with MAOIs and possibly TCAs. Additive vasoconstricting effects with ergot alkaloids, oxytocin.
Potentially Fatal: Risk of arrhythmia in patients undergoing anesthesia with cyclopropane and halothane.
- WHITTINGTON RM (May 1963). "Mephentemine Sulphate as a Hypertensive Agent in General Practice". J Coll Gen Pract 6 (2): 336–7. PMC 1878111. PMID 14000433.
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