ABSTRACT
The effect of pretreatment with graded concentration of diltiazem on the inotropic responses to amrinone were studied on isolated atria of rabbit. The responses to amrinone were modified by diltiazem in a biphasic manner; initial potentiation followed by inhibition. The potentiation is proposed to be due to synergistic rise in cytosolic calcium ion concentration by diltiazem and amrinone. The inhibition by diltiazem in higher concentration may be due to blockade of calcium ion influx and depletion of intracellular calcium ion from storage sites.
Subject(s)
Amrinone/pharmacology , Calcium Channel Blockers/pharmacology , Cardiotonic Agents/pharmacology , Diltiazem/pharmacology , Myocardial Contraction/drug effects , Phosphodiesterase Inhibitors/pharmacology , Animals , Atrial Function , Drug Synergism , Heart Atria/drug effects , Heart Atria/metabolism , In Vitro Techniques , RabbitsABSTRACT
In a double blind short term clinical study, nitroxazepine has been found to be superior over placebo in reducing the diastolic blood pressure in mild hypertensive patients. In short term open clinical trial design nitroxazepine (25 mg PO, HS) has been found to be superior and better tolerated than diazepam (5 mg PO, HS). In open clinical trial design, nitroxazepine (25 mg PO, HS) reduced the diastolic blood pressure to the target level (100 mm Hg and less) effectively controlling the uncontrolled hypertensive patients receiving maintenance dose of beta blockers. There was no such beneficial effect in patients receiving maintenance doses of other antihypertensive drugs (pilot study). Adverse drug reactions like disturbed sleep in one, uneasiness in 3, palpitation in one and dryness of mouth in one patient have been observed.
Subject(s)
Antihypertensive Agents/therapeutic use , Blood Pressure/drug effects , Dibenzoxazepines/therapeutic use , Hypertension/drug therapy , Adrenergic beta-Antagonists/therapeutic use , Adult , Antihypertensive Agents/adverse effects , Diazepam/adverse effects , Diazepam/therapeutic use , Dibenzoxazepines/adverse effects , Double-Blind Method , Humans , Hypertension/physiopathology , Pilot ProjectsABSTRACT
Diltiazem, a calcium channel blocker was studied to observe its effects on the acetylcholine contractile responses of isolated frog rectus abdominis muscle. This response was modified in a dual manner i.e., initial potentiation, followed by inhibition. Diltiazem may not have anticholinesterase like mechanism, as it potentiated the responses to both acetylcholine and succinylcholine. Rectus muscle preparation, incubated in calcium free frog Ringer, showed dose dependent inhibition of acetylcholine contractile responses by diltiazem. The study suggests that diltiazem inhibits calcium ion influx across receptor operated calcium channels and may also inhibit calcium ion release from intracellular structures.