Nitric acid Isosorbide dinitrate

Various esters of nitric acid (HNO3) and polyvalent alcohols relax vascular smooth muscle, e.g., nitroglycerin (gly-ceryltrinitrate) and isosorbide dinitrate. The effect is more pronounced in venous chan in arterial beds. 

Isosorbide Dinitrate Isosorbiddinitrate, 1,4 3,6-dianhydrosorbate-2,5-dinitrate (19.1.4), is synthesized by intermolecular dehydration of D-sorbite into isosorbide (19.1.3) using para-toluenesulfonic acid and subsequent nitration of the two hydroxyl groups by nitric acid [5-7]. 

Organic nitrates (and nitrites) are simple nitric and nitrous acid esters of alcohols. They differ in their volatility for example, isosorbide dinitrate is solid at room temperature, nitroglycerin is only moderately volatile, whereas amyl nitrate is extremely volatile. These compounds cause a rapid reduction in myocardial oxygen demand followed by rapid relief of symptoms. They are effective in stable and unstable angina, as well as Prinzmetal s or variant angina pectoris. 

The oldest class of clinically used NO donors are the organic nitrates (R-ONO2) (Fig. 20.3), which are nitric acid esters of mono and polyhydric alcohols, including glyceryl trinitrate (GTN A.l), pentaerithrityl tetranitrate (PETN A.2), isosorbide dinitrate (ISDN A.3), and isosorbide-5-mononitrate (ISMN A.4). Metabolites of GTN, viz., glyceryl mononitrate (GMN) and glyceryl dinitrate (GDN), are pharmacologically active, but less potent than GTN. 

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