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Farmaci Calcio Antagonisti 26 Marzo 2004

Farmaci Calcio Antagonisti 26 Marzo 2004. CENTRALI Stimolanti Metildopa Clonidina Altri Reserpina b bloccanti?. SITI DI AZIONE DEI FARMACI ANTIIPERTENSIVI. Inibitori delle catecolamine. a. b. VASODILATATORI DIRETTI Idralazina a -BLOCCANTI Prazosina CALCIOANTAGONISTI Nifedipina

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Farmaci Calcio Antagonisti 26 Marzo 2004

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  1. Farmaci Calcio Antagonisti26 Marzo 2004

  2. CENTRALI • Stimolanti • Metildopa • Clonidina • Altri • Reserpina • b bloccanti? SITI DI AZIONE DEI FARMACI ANTIIPERTENSIVI Inibitori delle catecolamine a b • VASODILATATORI DIRETTI • Idralazina • a-BLOCCANTI • Prazosina • CALCIOANTAGONISTI • Nifedipina • Verapamil • Diltiazem sinapsi Bloccanti Diuretici vasodilatazione Renina Angio tensina II vasocostrizione

  3. Formule chimiche dei calcio antagonisti Verapamil Diltiazem Nifedipine

  4. Ca2+antagonisti modalità d’azione

  5. Struttura del canale del calcio I II III IV +++ +++ +++ +++ S6 S2 S3 S5 S1 S4 Top view N III II IV I I IV C

  6. CCB binding to Ca++ channel DHP aloneBZT + DHPPAA + BZT

  7. State dependent affinity for dihydropyridines 100 0.36 nM 730 nM Ca current (%) EH= -15 mV EH= -80 mV 50 0 10-10 10-9 10-8 10-7 10-6 10-5 Nitrendipine (M)

  8. State dependent binding Depolarized -60 +40 Repolarized Resting Activated Inactivated + drug Activated * Inactivated* Prolonged recovery time course - drug

  9. Ca channel shape action potential Cardiac pacemaker Cardiac ventricle EM (mV) 0 0 -50 -80 100 ms 250 ms Vascular smooth muscle Central neuron EM (mV) 0 0 50 30 20 ms 500 ms

  10. Excitation-contraction coupling mechanismsin muscle cells Excitation Excitation Excitation Ca2+ Ca2+ Receptor Membrane SR Ca2+ Ca2+ Ca2+ SR Ca2+ SR Ca2+ Activator Ca2+ Activator Ca2+ Activator Ca2+ SKELETAL CARDIAC SMOOTH

  11. Ca2+ ANTAGONISTS: COMPARATIVE PROPERTIES V=D=N Diltiazem (Verapamil) Spasm - - SA LAD AV ecg - contractility Verapamil Diltiazem Peripheral arteriole - - N > V > D Variable effect: Usually cancelled by Afterload reduction Especially for N - - Opie. 1985 Nifedipine >V > D

  12. - Ca2+ ANTAGONISTS: COMPARATIVE PROPERTIES N >V=D experimentally V =N=D clinically Clinically D >V >N Or D =V >N Spasm - - SA LAD AV ecg Peripheral arteriole - Experimentally V=D >N Clinically ? V=D ? V >D contractility - N > V > D experimentally V >N, D clinically Nifedipine >V > D Or N >V=D Opie. 1987 RATIO NEG INOTROPIC TO VASCULAR EFFECT: V >D >N

  13. Pharmacokinetics of Ca2+ antagonists

  14. Half- life of some of the second generation calcium antagonists

  15. Effetti collaterali dei calcio antagonisti

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