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indicationFor the treatment of bronchospasm, chronic bronchitis, asthma, and emphysema.
pharmacologyOrciprenaline (also known as metaproterenol), a synthetic amine, is structurally and pharmacologically similar to isoproterenol. Orciprenaline is used exclusively as a bronchodilator. The pharmacologic effects of beta adrenergic agonist drugs, such as orciprenaline, are at least in part attributable to stimulation through beta adrenergic receptors of intracellular adenyl cyclase, the enzyme which catalyzes the conversion of adenosine triphosphate (ATP) to cyclic- 3',5'- adenosine monophosphate (c-AMP). Increased c-AMP levels are associated with relaxation of bronchial smooth muscle and inhibition of release of mediators of immediate hypersensitivity from cells, especially from mast cells.
mechanism of actionOrciprenaline is a moderately selective beta(2)-adrenergic agonist that stimulates receptors of the smooth muscle in the lungs, uterus, and vasculature supplying skeletal muscle, with minimal or no effect on alpha-adrenergic receptors. Intracellularly, the actions of orciprenaline are mediated by cAMP, the production of which is augmented by beta stimulation. The drug is believed to work by activating adenylate cyclase, the enzyme responsible for producing the cellular mediator cAMP.
toxicitySymptoms of overdose include angina, hypertension or hypotension, arrhythmias, nervousness, headache, tremor, dry mouth, palpitation, nausea, dizziness, fatigue, malaise and insomnia. LD50=42 mg/kg (orally in rat).
biotransformationHepatic and gastric. The major metabolite, orciprenaline-3-0-sulfate, is produced in the gastrointestinal tract. Orciprenaline is not metabolized by catechol-0-methyltransferase nor have glucuronide conjugates been isolated to date.
absorption3% (oral bioavailability of 40%)
half life6 hours
drug interactionsAcebutolol: Antagonism
Alseroxylon: Increased arterial pressure
Amitriptyline: The tricyclic antidepressant, amitriptyline, increases the sympathomimetic effect of orciprenaline.
Amoxapine: The tricyclic antidepressant, amoxapine, increases the sympathomimetic effect of orciprenaline.
Betaxolol: Beta-Blockers (Beta1 Selective) like betaxolol may diminish the bronchodilatory effect of Beta2-Agonists like orciprenaline. Therapy should be monitored.
Clomipramine: The tricyclic antidepressant, clomipramine, increases the sympathomimetic effect of orciprenaline.
Deserpidine: Increased arterial pressure
Desipramine: The tricyclic antidepressant, desipramine, increases the sympathomimetic effect of orciprenaline.
Doxepin: The tricyclic antidepressant, doxepin, increases the sympathomimetic effect of orciprenaline.
Imipramine: The tricyclic antidepressant, imipramine, increases the sympathomimetic effect of orciprenaline.
Isocarboxazid: Increased arterial pressure
Linezolid: Possible increase of arterial pressure
Methyldopa: Increased arterial pressure
Midodrine: Increased arterial pressure
Moclobemide: Moclobemide increases the sympathomimetic effect of orciprenaline.
Nortriptyline: The tricyclic antidepressant, nortriptyline, increases the sympathomimetic effect of orciprenaline.
Pargyline: Increased arterial pressure
Phenelzine: Increased arterial pressure
Protriptyline: The tricyclic antidepressant, protriptyline, increases the sympathomimetic effect of orciprenaline.
Rasagiline: Increased arterial pressure
Reserpine: Increased arterial pressure
Tranylcypromine: Increased arterial pressure
Trimipramine: The tricyclic antidepressant, trimipramine, increases the sympathomimetic effect of orciprenaline.