block Ca ions from entering cells

Ca channel antagonists

-treatment of 

hypertension and angina

-vasodilation of vascular smooth muscle (VSM)

(arteries not veins?)

-decrease heart rate, force of contraction, and conduction

Ca blocker effect on 

-vasodilation of vascular smooth muscle (VSM)

-decrease arterial pressure

-increases coronary perfusion 

                      arteries>veins 

3 Classifications of 

Ca Channel Blockers

dihydropyridines

verapamil

diltiazem

Verapamil

direct effect

-vasodilation of vsm arteries

-- decrease arterial pressure

--increase coronary perfusion

-decrease HR, contraction and conduction

Verapamil

indirect effect

-decrease BP= activation of baroreceptor

• in healthy pt will cause net effect:
• increase HR, force of contraction and conduction
• which can lead to increased load and action and cause heart failure

DONT USE ON HEALTHY HEART

Verapamil

pharmacokinetics

large first pass effect

-only 20% bioavability

-mostly metabolized in liver

Verapamil 

indications 

-angina

-essential hypertension

-dysrhythmias

-migraine prophylaxis

CC Rx

Verapamil

ADR's

CONSTIPATION

Vasodilation (intended effect)

-gingival hyperplasia

-excessive heart effects

--heart block

--bradycardia

CC Rx

Diltizem

overview

--less effect on heart

--more effect on VSM

-50% bioavability (hepatic)

--less ADRs

CCB Rx

Nifedipine

mechanism of action

most effect on VSM with baroreceptor reflex

-liiiittle heart action

-direct effect: dec BP

-indirect: baroreceptor 

--inc HR, contraction

Nifedipine

indications

and 

ADRS

-indicated for angina and hypertension

-ADRS: vasodilation: dizzy HA and edema

-can aggitate angina

-some negative inotropic effects

CCB Rx

Other Dihydropyridines

-____+ dipine

*nimodipine: not indicated for HT or angina

-specialized use in brain

*clevidipine: IV only