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Pharmacology
Calcium channel blockers
Question | Answer |
---|---|
ca+ enters cell via 3 types of voltage-dependent ca+ channels | L-type, N-type, T-type; L-type are long lasting channels predominant in cardiac and smooth muscle, ones blocked by most CCBs |
result of CCBs is marked decrease in transmembrane ca+ content and | prolonged vascular smooth muscle relaxation |
blocking action of CCBs occurs via 3 different receptors | diphenylalkylamine-based and benzothiazepine-based (type 1); dihydropyridine-based (type 2) |
only CCB to cross the blood brain barrier? | nimodipine (Nimitop) used for subarachnoid hemorrhage from ruptured intracranial berry aneurysm |
CCB of choice during lactation? | nifedipine (Procardia) |
dosage reduction for renal impairment is recommended only for? | nicardipine (Cardene) |
Verapamil should be avoided in CHF because? | it has the strongest negative inotropic effect |
type 1's are contraindicated for pts with EF<40% and for all other pts early post MI because? | negative inotropic and bradycardic effects |
Type 1's should not be used pts with? | ventricular dysfunction, sa or av nodal conduction disturbances, sbp<90 d/t high risk for HF and hypotension |
Type 2's (dihydropyridines) should be avoided in | post MI, unstable angina, significant peripheral edema d/t their strong peripheral vasodilating effects and may lead to reflex tachycardia |
Type 1's: | Diltiazem, verapamil |
Type 2's: dihydropyridines | amlodipine (Norvasc), felodipine (Plendil), isradipine (Dynacirc), nicardipine (Cardene), nifedipine (Procardia), nisoldipine (Sular) |
Adverse drug rxns occur less often with | long-acting formulations |
decreased myocardial contractility may lead to | HF |
verapamil, Cardizem, and Procardia may increase risk of digoxin? | toxicity |
drugs that inhibit the CYP3A4 system (including grapefruit juice) may increase? | free drug levels of CCB |
effective in tx of stable and exertional angina on supply and demand side | demand by: peripheral vasodilation and negative inotropism; supply by: dilation of coronary arteries |
Norvasc is not a sustained release but has a long half life of 30-50 hours which means? | it can be crushed unlike a sustained release but still provide the benefits of less venous pooling, less reflex tachycardia, and once daily dosing |
constipation occurs in almost 100% of pts taking? | verapamil |
CCBs used to treat Prinzmetal's angina | Cardizem, Procardia xl, norvasc |
CCBs not first line for unstable angina but if used ? is the drug of choice | verapamil |
only used in htn after ? have been considered | ACEIs, ARBs, diuretics, BBs |
Tx of SVT and Afib | Type 1's (verapamil and Cardizem) verapamil for PSVT prophylaxis |
if verapamil is used with dig it increases the risk of | dig toxicity |
should not be used in WPW | CCBs, digoxin |
Migrain h/a prophylaxis | verapamil at least 3 months of therapy needed to determine effectiveness |
Raynaud's syndrome | Type 2 (dihydropiridines) d/t their peripheral vasodilating effects, and platelet inhibition first choice: Procardia xl |
esophageal spasm | Cardizem has been used but should not be used with GERD |
with severe hepatic impairment | dosage reductions are recommended |
most common adverse reaction is | hypotension |