Nitroglycerine is used in Angina pectoris. The mechanism of action is primarily a: (A) Arteriolar dilator, (B) Post capillary venodilator, (C) Increase oxygen myocardial demand, (D) Decrease myocardial work load
Answer is B. (Post capillary venodilator): (540 KDT 7th edition)NITRATES (GTN, Nitroglycerine)* Most prominent action is exerted on vascular smooth muscleNitrates dilate veins more than arteries|Peripheral pooling of blood|Decreased venous return (ie preload on heart is reduced)|End diastolic size and pressure are reduced|Decreased cardiac work* Nitroglycerine are used sublingually because terminates first pass metabolism* *** Nitroglycerine is effective when retained sublingually because it is non-ionic and has very high lipid solubility (22-Goodman)