Metaraminol

log Kow= -0.27

0.6

-0.27

SOLUBILITY IN ALCOHOL: 1 G/100 ML /BITARTRATE/

INSOL IN CHLOROFORM, ETHER, ACETONE /BITARTRATE/

1.28e+01 g/L

Crystals; MP: 176-177 °C; pH of 1% aq soln: about 3.5; freely sol in water /l-form Bitartrate/

PRACTICALLY ODORLESS /BITARTRATE/

Hygroscopic; Specific optical rotation: -19.75 deg @ 20 °C/D; freely sol in water /l-form hydrochloride/

Manufacturers, packers, and distributors of drug and drug products for human use are responsible for complying with the labeling, certification, and usage requirements as prescribed by the Federal Food, Drug, and Cosmetic Act, as amended (secs 201-902, 52 Stat. 1040 et seq., as amended; 21 U.S.C. 321-392).

SRP: At the time of review, criteria for land treatment or burial (sanitary landfill) disposal practices are subject to significant revision. Prior to implementing land disposal of waste residue (including waste sludge), consult with environmental regulatory agencies for guidance on acceptable disposal practices.

MAO INHIBITORS...HAVE THE POTENTIAL FOR DRUG INTERACTION WITH METARAMINOL THROUGH INHIBITION OF OXIDATIVE DEAMINATION OF SYMPATHOMIMETIC AMINES. THE RESULT MAY BE AN INCREASED TISSUE STORE OF NOREPINEPHRINE, WHICH WILL PRODUCE A HEIGHTENED HYPERTENSIVE RESPONSE SECONDARY TO THE INDIRECT ACTIONS OF METARAMINOL. /BITARTRATE/

GUANETHIDINE, RESERPINE, & METHYLDOPA AFFECT POSTGANGLIONIC NERVE ACTIVITY, EITHER BY DECREASING NOREPINEPHRINE STORES OR BY EFFECTING ITS RELEASE. THEREFORE, THESE DRUGS WILL INTERFERE WITH THE INDIRECT NOREPINEPHRINE-RELEASING ACTIONS OF METARAMINOL & MAY LIMIT ITS EFFICACY. /BITARTRATE/

C - Cardiovascular system

QC - Cardiovascular system

Metaraminol is a potent sympathomimetic amine that increases both systolic and diastolic blood pressure. Metaraminol is indicated for prevention and treatment of the acute hypotensive state occurring with spinal anesthesia. It is also indicated as adjunctive treatment of hypotension due to hemorrhage, reactions to medications, surgical complications, and shock associated with brain damage due to trauma or tumor. Metaraminol acts on both α1-adrenergic receptors but appears to have no effect on β-adrenergic receptors. It acts by increasing the force of the heart's pumping action as well as constricting peripheral blood vessels.

Metaraminol acts through peripheral vasoconstriction by acting as a pure alpha-1 adrenergic receptor agonist, consequently increasing systemic blood pressure (both systolic & diastolic). Its effect is thought to be associated with the inhibition of adenyl cyclase which leads to an inhibition of the production of cAMP. Another effect of Metaraminol is that it releases norepinephrine from its storage sites indirectly.

BY DIRECT ACTION ON ALPHA ADRENERGIC RECEPTORS & INDIRECT ACTION THROUGH THE RELEASE OF NOREPINEPHRINE FROM STORAGE SITES...PRODUCES VASOCONSTRICTION, INCREASED PERIPHERAL VASCULAR RESISTANCE, & A RESULTANT INCREASED BLOOD PRESSURE. REFLEX BRADYCARDIA USUALLY OCCURS &...RENAL & CEREBRAL BLOOD FLOW DECREASES. /BITARTRATE/

CARDIAC INOTROPY INCREASES, BUT LESS SO THAN WITH NOREPINEPHRINE & CARDIAC OUTPUT REMAINS UNCHANGED OR MAY SLIGHLY DECREASE IF BRADYCARDIA OCCURS. SOME BETA ADRENERGIC MEDIATED VASODILATION OCCURS WITH METARAMINOL, BUT ALPHA EFFECTS PREDOMINATE. /BITARTRATE/

FOLLOWING IV ADMIN OF 1.5 MG/KG TO RABBITS, THERE WAS A POSITIVE CORRELATION BETWEEN PLASMA DRUG LEVEL & ITS VASOPRESSOR EFFECT. DRUG IS APPARENTLY DIRECT-ACTING SYMPATHOMIMETIC AMINE & ITS ACTION IS PROBABLY TERMINATED BY ITS DILUTION IN BODY FLUIDS & TISSUE UPTAKE.