Pharm block 2 Flashcards
classes of diuretics
carbonic anhydrase inhibitors (acetazolamide); osmotic diuretics (mannitol); loop diuretics (furosemide - K+-wasting); thiazides (hydrochlorothiazide - K+-wasting); K+-sparing diuretics (triamterene/amiloride; spironolactone); natriuretic peptides (nesiritide)
carbonic anhydrase inhibitor drugs
acetazolamide; related: dorzolamide (topical, eye)
carbonic anhydrase inhibitors pk
oral, iv; excreted via proximal tubule
carbonic anhydrase inhibitors renal pd
indirectly blocks bicarb reabsorption; alkalinisation of urine; metabolic acidosis; inc K+ secretion downstream; inc NaCl reabsorption (-> tachyphylaxis)
carbonic anhydrase inhibitors intra-ocular pd
block NaHCO3 secretion; dec aqueous humor formation
carbonic anhydrase inhibitors choroid plexus pd
dec rate of cerebrospinal fluid formation
carbonic anhydrase inhibitors uses
glaucoma - topical dorzolamide, systemic acetazolamide in emergencies; urinary alkalinisation - inc excretion of weak acids (uric acid, cysteine, aspirin) (theoretical); mountain sickness - choroid (cerebral edema, respiratory alkalosis)
carbonic anhydrase inhibitors adverse effects
metabolic acidosis; kidney stones; renal K+-loss; CNS toxicity (drowsiness, paresthesias)
carbonic anhydrase inhibitors contraindications
hepatic cirrhosis (reversal of NH4+ -> trapping acidic urine by alkalinisation) - NH4+ -> hepatic encephalopathy
mannitol characteristics
non-absorbable, non-metabolizable sugar
mannitol pk
MUST be IV; excreted via glomerular filtration
mannitol pd
retains h2o in tubule; some inc in natriuresis
mannitol uses
water diuresis (when preferred to Na excretion); maintain tubular flow (non-responders -> test dose); reduce intra-cranial/-ocular pressure
mannitol adverse effects
EC volume expansion (-> CHF, pulmonary edema); dehydration, hypernatremia
loop diuretics
FUROSEMIDE; bumetanide; torsemide; ethacrynic acid
loop diuretics pk
oral, iv, instant onset
loop diuretics pd
inhibit Na/K/Cl symporter in thick ascending limb -> directly affects blood flow
furosemide uses
EMERGENCIES; edematous conditions (acute pulmonary edema, acute CHF); acute hypercalcemia/hyperkalemia; acute renal failure - adjust oliguria, inc K secretion (flushing tubules -> non-oliguric renal failure); anion overdose (combine w/saline - bromide, fluoride, iodide); forced diuresis; (hypertension, CHF - second line for refractory cases; short-term)
furosemide adverse effects
HYPOKALEMIA; hypokalemic metabolic alkalosis; ototoxicity; hyperuricemia (->gouty attack); hypomagnesaemia; allergic rxns (sulfonamide moiety)
furosemide contraindications
other ototoxic drugs (aminoglycoside antibiotics)
thiazide diuretics - hydrochlorothiazide pd
inhibition of NaCl symporter in distal convoluted tubule; UNLIKE LOOP diuretics -> inc Ca reabsorption
hydrochlorothiazide pk
usually oral
hydrochlorothiazide adverse effects
similar to loop diuretics (less pronounced); hypokalemia, hypokalemic metabolic acidosis; hyperuricemia; hypernatriuria; impaired carb tolerance, hyperlipidemia; allergic rxns
hydrochlorothiazide uses
hypertension - inexpensive, proven, effective, safe, one daily dose, no dose titration needed; congestive heart failure; nephrolithiasis from IDIOPATHIC HYPERCALCIURIA (normal serum Ca!) - intestinal Ca-hyperabsorbers, renal ca/PO4 leakers; nephrogenic diabetes insipidus
metolazone pk
oral (65% bioavail)
metolazone pd
similar to thiazide diuretics; also effective when GFR<30ml/min;
metolazone uses
hypertension; edema; use instead of other thiazides in combo treatment of FUROSEMIDE RESISTANCE
K+-sparing diuretics - triamterene, amiloride pk
triamterene - hepatic metabolism, renal excretion; amiloride - renal excretion
triamterene, amiloride pd
mild inc in NaCl excretion via effects in late distal tubule/collecting duct
triamterene, amiloride adverse effects
HYPERKALEMIA (muscle weakness, fatigue, arrhythmia) esp in combo w/ACE inhibitors; metabolic acidosis; triamterene - acute renal failure (w/indomethacin), kidney stones
K+-sparing diuretics - spironolactone pk
prodrug of canreonate - IV
spironolactone pd
aldosterone antagonist -> delayed effect; mild inc in NaCl excretion in the late distal tubule, collecting duct
spironolactone adverse effects
HYPERKALEMIA esp. in combo w/ACE inhibitors; metabolic acidosis; gynecomastia
natriuretic peptide - nesiritide characteristics
B-type; in cardiac ventricles, released in response to myocardial distenstion; drug from E. coli; counterregulation of RAAS
nesiritide pk
IV peptide drug
nesiritide pd
activate guanylyl cyclase -> vascular smooth muscle relaxation; interlinked antagonisms for renin, ATII, aldosterone, ADH - inc GFR, dec Na reabsorption
nesiritide uses
acute severe heart failure
five classes of antihypertensive drugs
diuretics, beta-andrenoceptor antagonists (beta-blockers), Ca-channel blockers, angiotensin inhibitors (ACE inhibitors, AT1 blockers), alpha-adrenergic blockers
centrally-acting antihypertensive drugs
clonidine, methyldopa, reserpine
vasodilators
nitrates, nitroprusside, dihydralazine
classification of blood pressure for adults
normal =160/>=100
(reserpine) characteristics
rauwolfia alkaloid; obsolete but good model drug
(reserpine) pk
oral; effects persist for up to 6 weeks (intolerable)
(reserpine) pd
depletes biogenic amines from neuronal vesicles by inhibition of reuptake, CNS/periphery
(reserpine) uses
none
(reserpine) adverse effects
denervation of sympathetic system -> parasympathetic system prevails; nasal congestion, hypersecretion (bad for asthmatics); bronchoconstriction; mental depression (suicidal thoughts); parkinsonism; ulcerogenic
clonidine characteristics
alpha2 sympathomimetic drug; 2nd choice for treating hypertension; interesting off-label uses
clonidine pk
oral, iv, transdermal patch
clonidine pd
centrally mediated hypotensive effects - alpha2 agonist -> dec CO, relax capacitance of vessels, dec peripheral resistance -> renal blood flow maintained; may have initial hypertensive episode; pronounced rebound after prolonged use
clonidine uses
2nd line treatment of hypertension
clonidine adverse effects
high doses -> bradycardia, AV-block, fxn’l cardiac failure, dry mouth, drowsiness, sedation, constipation
clonidine other clinical uses
symptomatic treatment of w/drawal syndromes (heroin, alcohol, benzodiazepines); prevent/treat alcoholic delirium; postmenopausal syndrome; refractory diarrhea (short bowel syndrome); adjunct in analgo-sedation (->dexmedetomidine)
methyldopa characteristics
centrally acting antihypertensive safe in PREGNANCY
methyldopa pk
oral
methyldopa pd
centrally mediated hypotensive effects comparable, not identical, to clonidine
methyldopa adverse effects
mostly like clonidine; Coombs test may turn positive
alpha1-blockers
prazosin, terazosin, doxazosin
prazosin, terazosin, doxazosin pk
oral, iv
prazosin, terazosin, doxazosin pd
blockade of alpha1-receptors in arterioles/venules; no effect on inhibitory feedback for NE release (selective for alpha1)
prazosin, terazosin, doxazosin adverse effects
first dose phenomenon (hypotension, syncope) -> give initial dose at bedtime; orthostatic hypotension; tests for antinuclear factor (ANF) may turn positive (reflex tachy)
choice of diuretic drug in hypertension
CHOICE: thiazides (hydrochlorothiazide); 2nd line: K+-sparing - amiloride, triamterene, spironolactone; for GFR <30ml/min or refractory hypertension - loop diuretic (furosemide) or thiazide (METOLAZONE)
rules for routine use of thiazides
low dose, take in morn; combo w/k-sparing diuretic if hypokalemia a problem (watch for hyperkalemia); keep pt on dry weight but may cause dehydration -> mental confusion, aggravate COPD, peripheral arterial occlusive disease; important adverse effects - hypokalemia, hyperuricemia, impaired glucose tolerance, hyperlipidemia
beta-adrenoceptor antagonists (beta-blockers)
propranolol (non-selective); atenolol, metoprolol (beta1>beta2); pindolol (partial agonist); labetalol (alpha, beta-blocker, beta2 agonist); carvedilol (alpha/beta blocker); esmolol (beta1>beta2, short-acting, emergencies)
beta-blockers characteristics
beta1 selectivity is relative -> NEVER use for asthma, COPD; use in CHF is tricky - use tiny doses
unselective beta-blockers contraindications
pregnancy; diabetes; beta1-blockers can be considered; asthma, COPD, PAD, SA/AV abnormalities
alpha1-blockers vs. beta-blockers
alpha1-blockers don’t affect insulin-sensitivity -> minimal changes in CO -> don’t cause cold extremity syndrome; beta-blockers don’t cause orthostatic hypotension
calcium channel blockers
VERAPAMIL, diltiazem, nifedipine (and dihydropyridines); huge advantage over beta-blockers bc can give to diabetics, asthmatics, in pregnancy, COPD
verapamil, diltiazem, nifedipine pk
oral, iv, bound by serum proteins
verapamil, diltiazem, nifedipine pd
block L-type ca channels -> “cardiodepressant” (antiarrhythmic), arteriolar vasodilation
nifedipine (dihydropyridine) adverse effects
due to excessive vasodilation -> dizziness, headache, REFLEX TACHY, peripheral edema, constipation
verapamil, diltiazem adverse effects
bradycardia, slow SA/AV conduction
MI risk with antihypertensive drug therapy
short-acting, fast acting Ca channel blockers nifedipine, diltiazem and verapamil was associated w/inc risk of MI
second generation Ca channel blockers - long-acting
AMLODIPINE (standard - no inc risk of MI), felodipine, nisoldipine
second generation Ca channel blockers - slow onset
AMLODIPINE, felodipine
second generation Ca channel blockers - increased vascular selectivity
nisoldipine
second generation Ca channel blockers - increased potency
isradipine
interaction Ca channel-blockers and beta-blockers
beta blockers can potentiate the vasodilating effects of ca-channel blockers; 1+1=3
angiotensin inhibitors
ACE - inhibitors; ATII (AT1 subtype)-blockers
ACE-inhibitors
CAPTOPRIL, enalapril, enalaprilat, lisinopril, benzaepril, fosinopril, moexipril, quinapril, ramipril; all used for hypertension, some also for CHF
ATII (AT1)-blockers
losartan (hypertension, CHF); valsartan (hypertension)
ACE inhibitors - captopril pk
oral
captopril pd
ATII antagonism (ACE inhibition) -> dec vasoconstriction/NE release/ aldosterone secretion
bradykinin-related ACE inhibition pd
keeps bradykinin active -> vasodilation -> no reflex tachy, no significant change in CO, no h2o/na retention, some dec of sympathetic tone
captopril adverse effects
hypotension, dry cough, bronchospasm, skin rashes, angioneurotic edema, neutropenia, leukopenia, taste perversion, hyperkalemia, proteinuria
captopril contraindications
renal artery stenosis, renal failure; history of angioedema (asthma, COPD); pregnancy (oligohydramnion)
captopril toxicity
hypotension w/o marked tachy
captopril unwanted interactions
NSAIDs inhibit bradykinin pathway - dec antihypertensive response; K-sparing diuretics aggravate hyperkalemia; hypersensitivity to other drugs can be aggravated; inc plasma levels of digoxin, lithium
captopril therapeutically exploited interactions
K-wasting diuretics yield over-additive antihypertensive effect
ACE inhibitors - enalapril/enalaprilat characteristics
enalapril is prodrug of enalaprilat
enalapril pk
oral
enalaprilat pk
iv - hypertensive emergencies
enalapril, enalaprilat pd compared to captopril
longer duration of action
enalapril, enalaprilat adverse effects compared to captopril
no sulfhydryl-group -> no taste perversion
ACE inhibitors - others
most are prodrugs; fosinopril, moexipril - hepatic elminiation,, others renal;
ACE-inhibitors uses
hypertension; chf; MI; progressive renal disease in diabetic nephropathy (hyper-and normo-tensive pt’s)
losartan characteristics
angiotensin II subtype 1 blocker (AT1 blocker)
losartan pk
oral
losartan pd
LIKE ACE-inhibitors -> dec vasocontriction, dec NE release, dec aldosterone secretion; UNLIKE ACE inhibitors -> NO effect on bradykinin
losartan adverse effects
like ACE inhibitors (except bradykinin-related ae’s) - no/less cough, no angioedema
losartan contraindications
renal artery stenosis, renal failure, pregnancy
single drug therapy of hypertension
THIAZIDE or BETA BLOCKER or ca channel blocker or ACE inhibitor (or alpha1 blocker)
combination therapy of hypertension
thiazide w/beta-blocker, ca channel blocker, or ACE inhibitor; ca channel blocker w/beta-blocker or ACE inhibitor
triple therapy of hypertension
combo therapy with furosemide or clonidine
positive criteria for selection of antihypertensive drugs - diuretics
old age, black race, chf, chronic renal failure (loop diuretics)
positive criteria for selection of antihypertensive drugs - beta-blockers
youth, white, post-MI, migraine, senile tremor, atrial fibrillation (to control ventricular rate), paroxysmal supraventricular tachy
positive criteria for selection of antihypertensive drugs - long-acting ca channel blockers
old age, black race, migraine
positive criteria for selection of antihypertensive drugs - ACE inhibitors
youth, white race, type I diabetes w/nephropathy, impotence from other drugs; NOT IN PREGNANCY
positive criteria for selection of antihypertensive drugs - AT1-blockers
same as ACE inhibitors but can’t be used due to hypersensitivity/cough; NOT IN PREGNANCY
positive criteria for selection of antihypertensive drugs - alpha-blockers
prostatism, diabetes mellitis, dyslipidemia
Traditional treatment of CHF
inotropic - muscle changes
vasodilators used for chf
hydralazine - arterioles; minoxidil - arterioles; nitrates - veins/venules; ACE inhibitors - arterioles, veins
treating a symptom - fatigue
rest, positive inotropes
treating a symptom - edema
salt restriction, diuretics, digitalis
treating a symptom - dyspnea
diuretics (loop)
treating a symptom - congestion
nitrovasodilators, diuretics
treating a symptom - poor cardiac contractility
positive inotropes, digitalis
treating a symptom - increased pre/afterload
ACE inhibitors, ang-blockers, veno/vasodilators
treating a symptom - cardiac tissue remodeling
ACE inhibitors, ang-blockers, beta-blockers, spironolactone
treating a symptom - irreversible heart failure
heart transplantation
cardiac glycosides
digoxin, digitoxin
problems with cardiac glycosides
narrow therapeutic margin; complicated/unfavorable pk; sensitivity varies b/n pt’s, could change during therapy; severe, lethal ae’s
digoxin cardiac effects
inc myocardial contractility; dec sinus HR (- chronotropic effect) mainly due to vagal nerve input to SA node; dec AV conduction velocity - prolong refractory period in AV (- dromotropic effect); inc automaticity/excitability in atria, purkinje, ventricles
digoxin possible therapeutic benefits
inc CO; improve tissue perfusion; improve diuresis -> resorption of edema; dec sympathetic tone, vasoconstrction; dec peripheral resistance (afterload); dec preload; dec myocardial overdistension; improve working efficiency -> favorable; improve symptoms, but NO DEC IN DEATHS
digoxin adverse effects
arrhythmia: tachyarrhythmia (premature ventricular contractions, ventricular fibrillation - low K+), bradyarrhythmia (non/paroxysmal atrial tachy, AV-block - high K+); GI - anorexia, nausea, vomiting, diarrhea; CNS - headache, malaise, neuralgias, delirium (Van Gogh Starry Night)
digoxin precipitating factors for adverse effects
hypo/hyperkalemia; drug accumulation/overdose; hypomagnesemia, hypercalcemia; hyperthyreosis; abnormal renal fxn; respiratory disease; acid-base imbalances
digoxin toxicity treatment
w/draw drug; monitor plasma dig, K levels, ECG; adjust electrolyte status; ventricular tachyarrhythmia - lidocaine, mg2+, adjust K to high normal
severe digoxin toxicity
associate with hyperkalemia -> bradyarrhythmias, suppressed automaticity -> temp pacemaker; digitalis antibodies (digoxine immune fab, digibind)
digoxin indications
chf grade NYHA III/IV; antiarrhythmic therapy for atrial flutter/fibrillation
digoxin non-indications
ineffective in myocarditis, corpulmonale; uncontrolled hypertension; bradyarrhythmias; non-responders or intolerance (severe ae’s)
ACE inhibitors uses
hypertension, chf, MI, progressive renal disease
ACE inhibitors uses - CHF
prevent/delay progression of heart failure (can’t improve ejection fraction); dec incidence of sudden death, MI; dec hospitalization; improve quality of life
ACE inhibitors uses - MI
dec mortality when started in periinfarction period (no later than 16 days post MI)
how to use a beta-blocker
start low (10%dose, go slow); clinical assessment b4 every inc in dose (NYHA III - outpatient, NYHA IV - hospitalize); late onset of benefit (3mths - 12/18mths); give w/diuretics, ACE inhibitors, digitalis (keep as constant as possible, manages side effects); only method that can INCREASE EJECTION FRACTION
managing side effects of beta-blockers in treating CHF
give w/diuretics, ACE inhibitors, digitalis; try to maintain beta-blocker, consider: sedation, hypotension (to reduce diuretics, ACE inhibitors), edema (inc diuretic), bradycardia, AV-block (dec digitalis)
Last resort treatments
inotropic drugs for acute cardiac failure; keep pt alive for few more days/weeks - dopamine (low dose, act on dopamine receptors in kidney); dobutamine (iv; acts on alpha/beta receptors, inc CO w/o affecting HR); amrinone/milrinone (inc myocardial cAMP by inhibiting PDE III, inc contractile system sensitivity to ca; vaso/venodilation -> potentiates effect of dobutamine -> kills pt)
Class I antiarrhythmic drugs - fast channel blockers (Na)
quinidine, lidocaine, flecainide
Class II antiarrhythmic drugs - beta-blockers (Ca)
propranolol (beta antagonist), atenolol (beta1 antagonist), esmolol (short-acting beta1 antagoinst), sotalol (beta antagonist, k-channel blocker)
Class III antiarrhythmic drugs - inhibitors of repolarization (K)
prolong AP, ERP; amiodarone, bretylium (indirect sympatholytic, antihypertensive), sotalol, ibutilide (emergencies), dofetilide (like sotalol, less ae’s)
Class IV antiarrhythmic drugs - calcium channel blockers (Ca)
verapamil, diltiazem
unclassified antiarrhythmic drugs
adenosine, atropine, digoxin, magnesium
main factors promoting arrhythmias
ischemia/hypoxia; acid-base imbalance; inc autonomic input; drug toxicity (digitalis, antiarrhythmic drugs); overstretching cardiac fibers (chf); impaired tissue (MI survivors)
all arrhythmias result from:
disturbance in impulse formation, conduction, or combo of both
delayed afterdepolarization
result of ischemia, anything that affects cAMP (E/NE, theophylline), digitalis, tachy
early afterdepolarization
result of brady, hypokalemia, action potential delaying drugs
principles to therapy of cardiac arrhythmias
eliminate/minimize precipitating factors; define arrhythmia type (brady/tachy? ventricular/supraventricular?); minimize risks of doing drug therapy -> most cause arrhythmias!
goals of therapy of cardiac arrhythmias
terminate ongoing arrhythmia; prevent recurrence
class IA antiarrhythmic drugs
inhibits Na AND k channels -> prolonged repolarization; quinidine, procainamide, disopyramide
class IB antiarrhythmic drugs
accelerated repolarization; lidocaine (used for resuscitation), mexiletine, tocainide (phenytoin)
class IC antiarrhythmic drugs
little effect - rarely used; flecainide, propafenone
quinidine pk
oral, IM, BID, QID (iv - watch for arrhythmia, hypotension)
quinidine pd
na channel block in ACTIVATED STATE -> dec vmax in phase 0; block K channels -> prolong AP; antimuscarinic (low doses) -> inc AV-conduction (paradoxically); alpha-blocker (high conc)
quinidine cardiac effects
block Na channels in ACTIVATED STATE -> dec automaticity; dec conduction/excitability; recovering from blockade - slower in depolarized than polarized tissue; RESULT: prolonged refractory period esp in depolarized tissue; block K channels - dec max re-entry frequency -> prolong AP, ERP
quinidine EKG effects
prolong QRS (delays conduction in bundle of His, purkinje); prolong QT, alter T-wave (delays repolarization); variable prolongation of PR (slows AV conduction)
quinidine cardiac adverse effects
dec CONTRACTILITY (- inotrope); paradoxical inc sinus rate, av-conduction (antimuscarinic actions) -> remove protective av-block -> ventricular tachy; torsade des pointes - polymorphic ventricular tachy -> could kill, self-limiting (quinidine syncope); excessive dec conduction -> toxic (AVB, asystolia) - serum K > 5, quinidine > 5
quinidine extracardiac pd
antimalarial (2nd line, CHOICE for falciparum malaria); hypotensive (alpha-blocker)
quinidine extracardiac adverse effects
GI disturbances; CNS - cinchonism (overdose of cinchona) - headache, dizziness, tinnitus
quinidine extracardiac drug interactions
compete for CYP450 w/digoxin, verapamil, others
quinidine use
supraventricular arrhythmias - paroxysmal supraventricular tachy, wolff-parkinson-white syndrome, convert atrial flutter/fibrillation to sinus rhythm as adjunct/2nd-line treatment; do not use w/o prior digitlization
procainamide characteristics
amide of procaine; protected from enzymatic hydrolysis; less cns effects
procainamide pk
oral; iv arrythmia, hypotension
procainamide pd
LIKE quinidine; block na channels in activated state, block K channels; antimuscarinic (less than quinidine); alpha-sympatholytic
procainamide adverse effects
cardiac/GI - like quinidine; cns - mental confusion, psychosis, less frequent than w/lidocaine; hypersensitivity (much more often w/quinidine), lupus-like syndrome (reversible), 70% w/ANAs; hypotension; antimuscarinic - aggravates glaucoma, urinary retention
procainamide uses
indications similar to quinidine -> try other if one doesn’t work; 2nd choice after lidocaine for sustained ventricular arrhythmias w/acute MI; oral - sustained release for prolonged therapy; iv - infusion, ECG-monitoring, control plasma levels
class IB - lidocaine characteristics
amide local anaesthetic
lidocaine pk
ONLY iv
lidocaine pd
block IN/ACTIVATED na channels -> more pronounced effect in tissues w/long plateaus (purkinje, ventricular) and depolarized tissue; little effect on K-channels -> shorten AP duration (effect depolarized, arrhythmogenic tissue)
lidocaine cardiac adverse effects
exacerbate arrhythmias; SA-standstill in pt’s w/MI
lidocaine cns adverse effects
paresthesias; toxic - convulsions, coma (very high doses)
lidocaine drug interactions
agents that interfere w/hepatic perfusion, microsomal metabolism
lidocaine uses
CHOICE for ventricular tachy, fibrillation after cardioversion; suppress arrhythmia assoc w/depolarization (post MI, dig toxicity); NOT for prolonged prophylactic use post-MI
mexiletine characteristics
orally active congeners of lidocaine
mexiletine pk
oral
mexiletine pd
same as lidocaine
mexiletine adverse effects
frequent w/therapeutic doses; cns - nausea, tremor, blurred vision, lethargy; allergic - rash, fever, agranulocytosis
(phenytoin) characteristics
antiepileptic drug similar to phenobarbital
(phenytoin) pk
oral, iv
(phenytoin) pd
same as lidocaine
(phenytoin) adverse effects
cns - sedation, nystagmus, vertigo, loss of mental accuity; gingival hyperplasia
class IC - flecainide, propafenone characteristics
very slow dissociation from na channel during recovery; use in life-threatening, refractory arrhythmia; flecainide CAST - inc mortality in post MI pt’s treated for premature ventricular contractions -> use ONLY oral for atrial arrhythmias in hearts otherwise uncompromised
class II prototype drug - propranolol cardiovascular effects
dec SA freq -> sinus brady; dec automaticity in purkinje; prolong ERP of AV-node; suppress ectopic ventricular depolarizations; - inotrope; diverse hemodynamic effects
propranolol cardiovascular adverse effects
hypotension, aggravation of chf, asystolia
propranolol uses
dec risk of sudden death in post MI; control supraventricular tachy; exercise/stress-precipitated ventricular arrhythmias; ischaemic heart disease, angina pectoris
class III - amiodarone pk
2 weeks to reach steady state; 30-120 days half life
amiodarone pd
block INACTIVATED na channels - most pronounced in tissues w/long plateaus (purkinje, ventricular), depolarized; block k-channels; weak ca channel, beta blocker
amiodarone adverse effects
can deposit in tissues (slowly reversible) -> pulmonary fibrosis, corneal deposits, photodermatitis, skin discoloration; cns - paresthesias, tremor, ataxia, headache; thyroid dysfxn; GI/liver toxicity
amiodarone drug interactions
digoxin, theophylline, warfarin, quinidine
class III - sotalol characteristics
racemic mix used
sotalol pk
oral, iv
sotalol pd
block k-channels; beta blocker
sotalol adverse effects
same as beta blockers; proarrhythmic (torsades des pointes)
sotalol uses
treat/prophylaxis of severe ventricular tachyarrhythmias, atrial arrhythmias
ca channel blockers - verapamil, diltiazem characteristics
block L-type ca-channels in in/activated states; most pronounced effect on AV-conduction
verapamil, diltiazem uses
re-entrant supraventricular tachy; dec ventricular rate in atrial fib, flutter; ischaemic heart disease, angina pectoris; hypertension
adenosine characteristics
ubiquitous auto/para/endocrine compound
adenosine pk
iv infusion
adenosine pd
purine-p1 receptor agonist; inc k-conductance, inhibits cAMP-mediated ca influx -> hyperpolarization, esp in av-node
adenosine uses
conversion of narrow complex paroxysmal ventricular tachy (PSVT)
adenosine adverse effects
transient (short t1/2) -> flushing, av-block III, chest pain, atrial fib, bronchoconstriction esp in asthmatics
miscellaneous antiarrhythmics
potassium; magnesium (ca-antagonist - treat torsades des pointes, dig-induced arrhythmia, prevent arrhythmia in acute MI); digoxin (slow av conduction); atropine (bradyarrhythmia -> dec vagal tone)
drug therapy for atrial fibrillation
- dromotropic agents -> digoxin, verapamil/diltiazem, beta-blockers; induce/maintain sinus rhythm - block fast action potentials (class IA, IC, III antiarrhythmics)
angina treatment drugs
nitrates, beta-blockers, ca-channel blockers
angina combination treatment
nitrate + beta-blocker
nitrates
nitroglycerine, isosorbide dinitrate (ISDN), isosorbide mononitrate (ISMN)
nitrates pd
relax smooth muscles, including vascular; fast relaxation of venous tone -> inc capacitance, dec preload; slowly dec arteriolar resistance -> dec myocardial O2 demand
nitrates pk
nitroglycerine - subligual, buccal, transderma, iv; NOT oral
nitrates adverse effects
vasodilation -> headache, flushing; hypotension -> reflex tachy, dizziness, weakness, cerebral ischaemia; nitrate tolerance
nitrates uses
acute/anticipated attacks of angina; prolonged preventative therapy (ISMN, ISDN); paroxysmal nocturnal dyspnea in chf; spasmolytic in colic pain (biliary, renal, intestinal)
factors that induce nitrate tolerance
prolonged nitrate exposure (patch, sustained release, iv); large doses; frequent dosing
factors that prevent nitrate tolerance
intermittent dosing; small doses; infrequent dosing; nitrate-free intervals
sodium nitroprusside characteristics
ferrocyanide compound; limit use to only some hours
sodium nitroprusside pd
direct NO donator -> immediate vasodilation
sodium nitroprusside pk
iv infusion; protect from light, converted to cyanide, then thiocyanide
sodium nitroprusside uses
ICU/emergencies; controlled hypotension in surgery; some of severest cardiac failure
sodium nitroprusside precautions
borderline systolic BP; myocardial ischaemia w/o heart failure; hepatic/renal insufficiency
sodium nitroprusside adverse effects
nausea, vomiting, headache, cns disturbances
sodium nitroprusside toxicity
cyanide intoxication
ca channel blockers
verapamil, diltiazem, nifedipine (and dihydropyridines)
verapamil, diltiazem, nifedipine pk
oral, iv
verapamil, diltiazem, nifedipine pd
block L-type ca channels -> cardiodepressant, arteriolar vasodilation
verapamil, diltiazem, nifedipine adverse effects
dihydropyridines (excessive vasodilation) -> dizziness, headache, peripheral edema, reflex tachy; verapamil, diltiazem -> brady, slow SA/AV conduction
beta blockers for angina
propranolol, atenolol, metoprolol
beta blockers effects on angina
dec severity/freq in exertional angina; somewhat effective in unstable angina; cardioprotective in post MI (beta1 selective); ineffective in vasospastic angina - may worsen condition
antihyperlipidemic drugs
hmg coa reductase inhibitors (statins); niacin; fibrates; bile-acid binding agents; cholesterol absorption inhibitors; combination drug therapy
statins
lovastatin, sinvastatin, pravastatin, atorvastatin, fluvastatin, rosuvastatin
statins characteristics
CHOICE, most efficacious for inc LDL (hypercholesterolemia)
statins pk
cyp450
statins pd
inhibit hmg coa reductase (HMG analogs) -> inc LDL receptor expression (homozygotes for FH -> no LDL receptors -> no response); modest dec TGs; small inc HDL
statins adverse effects of monotherapy
myopathy, myositis w/rhabdomyolysis; inc transaminase, liver enzymes
statins adverse effects of combo therapy
interactions (cyp450); myopathy, myositis, rhabdomyolysis; inc risk of overdose of ther drugs
statins contraindications
pregnancy/lactation, hepatic disease, muscular disease
statin combinations
w/bile acid binding agent or cholesterol absorption inhibitor (more dec LDL); w/niacin - inc risk of myopathy; w/fibrates - inc risk of rhabdomyolysis (gemfibrozil)
bile-acid binding agents
cholestyramine, colestipol, colesevelam
cholestyramine, colestipol, colesevalem characteristics
2nd choice for lipid reduction; ensure ample fluid intake to avoid constipation
cholestyramine, colestipol, colesevalem pd
cationic resins - bind to negatively charged bile acids in sm intestine -> prevent reabsorption -> inc conversion of cholesterol to bile acids; inc LDL receptor
cholestyramine, colestipol, colesevalem pk
oral, fat soluble -> not absorbed/met’d; uncomfortable to ingest; completely excreted in feces
cholestyramine, colestipol, colesevalem interactions
acidic drugs, coumadin, vitamin c; dec absorption of fat-soluble vit’s, drugs (digoxin, warfarin, antiretrovirals, cyclosporin)
cholestyramine, colestipol, colesevelam uses
type IIa/b hyperlipidemias; only w/isolated inc in LDL; hypercholesterolemia in young (s w/biliary obstruction (pancreatic carcinoma)
cholestyramine, colestipol, colesevalem adverse effects
GI - constipation, nausea, bloating, flatulence
cholestryamine, colestipol, colesevalem combinations
w/statins or niacin -> more dec LDL
cholestyramine, colestipol, colesevalem contraindications
can upregulate vldl, TG synth -> caution in pt’s w/hypertriglyceridemia
niacin
nicotinic acid, vitamin b3
nicotinic acid, vitamin B3 characteristics
most effective agent to inc hdl
nicotinic acid, vitamin b3 pd
dec vldl, ldl, tg; inhibits lipolysis in adipose; dec FA’s -> dec triacylglycerol synth (req’d for vldl); inc HDL
nicotinic acid, vitamin b3 pk
oral; converted to nicotinamide -> used in NAD; niacin/metabolites excreted in urine
nicotinic acid, vitamin b3 uses
when statin contraindicated; familial hyperlipidemias; combo w/statins for severe hypercholesterolemias
nicotinic acid, vitamin b3 adverse effects
cutaneous flush, pruritus (vasodilator); hyperuricemia; hepatotoxicity; impaired insulin sensitivity (caution diabetics); combo w/statin -> inc risk of myopathy
fibrates
fenofibrate, gemifibrozil
fenofibrate, gemfibrozil pk
oral; bound to albumin
fenofibrate, gemfibrozil pd
dec vldl, tg’s; inc hdl; modest dec ldl; binds, activates PPARalpha (hepatocytes, sk muscle, macrophages, heart);
fenofibrate, gemfibrozil uses
hypertriglycerolemias; CHOICE for dysbetalipoproteinemia; pt’s not responding to diet/other drugs
fenofibrate, gemfibrozil adverse effects
mild GI; CHOLELITHIASIS; myositis
fenofibrate, gemfibrozil interactions
compete w/coumarin (warfarin) for plasma binding sites -> potentiates anticoagulant activity
fenofibrate, gemfibrozil contraindications
PREGNANCY safety not established
cholesterol absorption inhibitors
ezetimibe, plant sterols
ezetimibe, plant sterols pd
dec ldl (small dec tg’s, small inc hdl); inhibit absorption of dietary, biliary cholesterol; inhibit hepatic vldl synth; upregulation of ldl receptor
ezetimibe, plant sterols pk
oral; met in sm intestine, liver
ezetimibe, plant sterols uses
complementary to statins or in combo when statins inadequate; hypercholesterolemia when statin CI’d
ezetimibe, plant sterols adverse effects
diarrhea, ab pain, headache, rash, angioedema
ezetimibe, plant sterols contraindications
pregnancy, lactation
omega-3 fatty acids - fish oils characteristics
dec tg’s
fish oils pd
dec tg synth; inc fa oxidation
fish oils uses
tg > 500mg/dL