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Cardiovascular agents. Moustafa K Soltan. Cardiovascular agents are the drugs which act on heart and vascular system These drugs are used for treatment of angina, cardiac arrhythmia, hypertension, hyperlipidemia, and disorders of blood coagulation and platelet aggregation . Antianginal agents.
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Cardiovascular agents Moustafa K Soltan
Cardiovascular agents are the drugs which act on heart and vascular system • These drugs are used for treatment of angina, cardiac arrhythmia, hypertension, hyperlipidemia, and disorders of blood coagulation and platelet aggregation .
Antianginal agents • The English word angina (refers to a painful choking constriction or tightness somewhere in the body • Angina pectoris: chest pain due to ischemia (a lack of blood and hence oxygen supply) of the heart muscle • the principal symptom of Angina pectoris is characterized by a severe constricting pain in the chest, often radiating from the pericardium to the left shoulder and down the arm
Types of angina pectoris 1- stable angina occurs during exercise 2- unstable angina occurs during rest Treatment of angina pectoris 1- nitrovasodiltors 2- calcium channel blockers 3-drugs with anti platelet aggregation
1- Nitrovasodiltors Mode of action
Glyceryl trintrate 1-used sublingual or transdermal 2- it acts by decreasing cardiac work and reduce oxygen demands
N.B Organic nitrates (as glyceryl trinitrate) are preferred to be taken sublingualy for the following reason : # Only 15% of the cardiac output is delivered to the liver , this allows a transient but effective circulating level of the intact organic nitrate before it is inactivated . Metabolism of glyceryl trinitrate in the liver by reacting with glutathione leads to the conversion of a potent lipid-soluble vasodilator substance (glyceryl trinitrate)to a water-soluble metabolite of lower biological potency (glyceryl mononitrate) that is readily excreted in the urine .
Amyl nitrite Isopentyl nitrite or isoamyl nitrite has onset time (1/4 minute ) and its duration of action is ( one minute ) . Erythrityl tetranitrate : Erythritol tetranitrate or ( 1, 2, 3, 4-butanetetrol tetranitrate ) has onset time ( 15 minutes ) , longer duration ( 180 m ) so it is used in treatment and as a prophylactic agent against angina .
Penta-erythritol tetranitrate : 2, 2-bis (hydroxymethyl)-1, 3-propanediol tetranitrate Its onset time ( 20 m ) and longer duration ( 5 hours ) , and it is used as prophylacting to reduce the severity and frequency of anginal attacks .
Isosorbide dinitrate: 1,4 : 3,6 – dianhydrosorbitol – 2,5 –dinitrate Its onset time ( 3 m ) and duration (60 m) and it is effective in Treatment or prophylaxis of acute anginal attacks.
1- Dihydropyridine derivatives ( 1 , 4- DHP ) Nifedipine , Nicardipine , Nitrendipine , Nimodipine , Amlodipine and Felodipine . 2- 1 , 5 –Benzothiazepine derivatives Diltiazem 3- Aralkylamine derivatives : Bepridil and Verapamil .
1- Dihydropyridine derivatives ( 1 , 4- DHP ) Nifedipine 3,5-dimethyl2,6-dimethyl-4-(2-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylate Nifedipine is the prototype of 1,4-DHP class and is used in treatment of angina and hypertension .
Nicardipine 2-[benzyl(methyl)amino]ethyl methyl 2,6-dimethyl-4-(3-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylate Nicardipine is used in treatment of mild, moderate, and severe hypertension It has less negative inotropic effect than Nifedipine .This may be attributed to: Nicardipine lacks the anticoplannerity of phenyl and 1,4-DHP rings which is the first riquirement for fitting on the receptor .
Nitrendipine ethyl methyl 2,6-dimethyl-4-(3-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylate Nitrendipine is an effective vasodilator and is used in treatment of essential hyperetension .
Nimodipine 3-(2-methoxyethyl)5-propan-2-yl2,6-dimethyl-4-(3nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylate . Nimodipine is used in treatment of subarachnoid hemorrhage-associated neurological deficits, so it dilates the cerebral blood vessels .
Amlodipine 3-ethyl 5-methyl 2-[(2-aminoethoxy)methyl]-4-(2-chlorophenyl)-6-methyl-1,4-dihydropyridine-3,5-dicarboxylate Amlodipine has greater selectivity for the vascular smooth muscle than myocardial tissue , it is used in treatment of angina and essential hypertension. Amlodipine is used as a non-sustained-release product and can given once dialy due to its high binding to plasma protein ( more than 90% ) , andhas a twenty four hours duration of action compared with other calcium channel blockers
Felodipine ethyl 5-methyl 4-(2,3-dichlorophenyl)-2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylate Felodipine is an effective vasodilator and is used in treatment of angina and hypertension . It exhibits a high degree of protein binding and has a half-life ranging from ( 10-18 hrs ) .
2- 1 , 5 –Benzothiazepine derivatives : Diltiazem) ( + )-cis-3-( Acetoxy )-5-( 2-( dimethylamino )ethyl )-2,3-dihydro-2-( 4-methoxyphenyl )1,5-benzothiazepin-4( 5H ) one . Diltiazem is used in patients with variant angina , and is used as antiarrhythmic agent . The first-pass metabolism of Diltiazem resulted in deacetylation , oxidative O- demethylation or N-demethylation where the deacetylated metabolite has about 40-50% of the potency of the parent compound .
3- Aralkylamine derivatives Verapamil 5-( ( 3,4-dimethoxyphenethyl )-methylamino )-2-( 3,4-dimethoxyphenyl )-2-isopropylvaleronitrile . Verapamil is used in the treatment of angina pectoris ,and arrhythmias . The levorotatory enantiomer is the most potent . The first-pass metabolism involves N-demethylation followed by O-demethylation and the metabolites of Verapamil have no significant biological activity
Bepridil N-benzyl-N-(3-isobutoxy-2-pyrrolidin-1-yl-propyl)aniline. Bepridil is a second generation alkylamine-type channel blocker, its action is less specific than Verapamil but it is used for stable angina, and it has a half-life of 33hrs and is highly bounded to protein ( 99% ) .
Antianginal agent with antiplatelet activity Dipyridamol 2,6-Bis-( diethanolamino )-4,8-dipiperidino-pyrimido( 5,4-d )pyrimidine . its action is selective on the coronary system and is indicated for long-term therapy of chronic angina pectoris . The drug inhibits adenosine deaminase in erythrocytes and interferes with the uptake of the vasodilator adenosine by erythrocytes . These actions potentate the effect of prostacyclin acting as an inhibitor to platelet aggregation ( antithrombotic action ).
Questions 1- Give selective method for analysis of organic nitrates ? 2- Illustrate synthetic pathway of Isosorbide dinitrate ?