Lopressor

Lopressor HCT

metoprolol tartrate USP and hydrochlorothiazide USP

50/25 Tablets

100/25 Tablets

100/50 Tablets

Beta Blocker/Diuretic Antihypertensive

Rx only

Prescribing Information

Lopressor HCT has the antihypertensive effect of Lopressor, metoprolol tartrate, a selective beta-adrenoreceptor blocking agent, and the antihypertensive and diuretic actions of hydrochlorothiazide. It is available as tablets for oral administration. The 50/25 tablets contain 50 mg of metoprolol tartrate USP and 25 mg of hydrochlorothiazide USP; the 100/25 tablets contain 100 mg of metoprolol tartrate USP and 25 mg of hydrochlorothiazide USP; and the 100/50 tablets contain 100 mg of metoprolol tartrate USP and 50 mg of hydrochlorothiazide USP. Metoprolol tartrate USP is (±)-1-(Isopropylamino)-3-[p-(2-methoxyethyl)phenoxy]-2-propanol L-(+)-tartrate (2:1) salt, and its structural formula is

Metoprolol tartrate USP is a white, crystalline powder. It is very soluble in water; freely soluble in methylene chloride, in chloroform, and in alcohol; slightly soluble in acetone; and insoluble in ether. Its molecular weight is 684.82.

Hydrochlorothiazide is 6-chloro-3, 4-dihydro-2 H-1,2,4-benzothiadiazine-7- sulfonamide 1,1-dioxide, and its structural formula is

Hydrochlorothiazide USP is a white, or practically white, practically odorless, crystalline powder. It is freely soluble in sodium hydroxide solution, in n-butylamine, and in dimethylformamide; sparingly soluble in methanol; slightly soluble in water; and insoluble in ether, in chloroform, and in dilute mineral acids. Its molecular weight is 297.73.

Inactive Ingredients: Cellulose compounds, colloidal silicon dioxide, D&C Yellow No. 10 (100/50-mg tablets), FD&C Blue No. 1 (50/25-mg tablets), FD&C Red No. 40 and FD&C Yellow No. 6 (100/25-mg tablets), lactose, magnesium stearate, povidone, sodium starch glycolate, corn starch, stearic acid, and sucrose.

Lopressor is a beta-adrenergic receptor blocking agent. In vitro and in vivo animal studies have shown that it has a preferential effect on beta adrenoreceptors, chiefly located in cardiac muscle. This preferential effect is not absolute, however, and at higher doses, Lopressor also inhibits beta adrenoreceptors, chiefly located in the bronchial and vascular musculature.

Clinical pharmacology studies have confirmed the beta-blocking activity of metoprolol in man, as shown by (1) reduction in heart rate and cardiac output at rest and upon exercise, (2) reduction of systolic blood pressure upon exercise, (3) inhibition of isoproterenol-induced tachycardia, and (4) reduction of reflex orthostatic tachycardia.

Relative beta selectivity has been confirmed by the following: (1) In normal subjects, Lopressor is unable to reverse the beta-mediated vasodilating effects of epinephrine. This contrasts with the effect of nonselective (beta plus beta) beta blockers, which completely reverse the vasodilating effects of epinephrine. (2) In asthmatic patients, Lopressor reduces FEV and FVC significantly less than a nonselective beta blocker, propranolol at equivalent beta-receptor blocking doses.

Lopressor has no intrinsic sympathomimetic activity and only weak membrane-stabilizing activity. Lopressor crosse