Pharmacology

Question 1

Furosemide

Answer 1

• Diuretic
• MOA: loop diuretic and inhibits NA and water transport in the ascending loop of Henle (causing diuresis). One of the most potent diuretics.
• Tx: CHF
• SE: fliud loss and electrolyte changes (particularly potassium- become hypokalemic)

Papich

Question 2

Pimobendan

Answer 2

• Cardiac inotropic agent
• MOA: positive inotrope by acting as a phosphodiesterase III inhibitor adn increasing intracellular cAMP (because phosphodiesterase III degrades cAMP). Most of the theraputic effect is in its action as a calcium sensatizer- thus increasing interaction of troponin C with contractile proteins and acting as a inotropic agent. Also has vasodilating properties.
• Tx: CHF (and asymptomatic DCM)
• SE: potentially arrhythmogenic
• Use with caution with other phosphodiesterase inhibitors (theophylline, pentoxifylline and sildenafil)

Papich

Question 3

Clopidogrel

Answer 3

• Antiplatelet drug
• MOA: platelet inhibitor. It is a thienopyridine and inbibits (ADP)2y12 receptor( irreversible antagonst) mediated platelet activity (different then aspirin MOA) and secondary platelet aggregation. Also inhibits the ADP induced confromational change of the glycoprotein IIb/IIIa receptor complex. Effects are by an active metabolite
• Tx: often in cats prone to TE assocated with heart disease
• SE: bleeding

Papich

Question 4

Benazepril HCl

Answer 4

• Vasodilator, Angiotensin-Converting enzyme (ACE) inhibitor
• MOA: Inhibits conversion of Ang I to Ang II. Ang II is a potent vasoconstrictor and also stimulates sympathetic stimulation, renal hypertension and synthesis of aldosterone (which causes Na and water retention). ACE inhibitors cause vasodilation and decrease aldosterone induced congestion. Duel elimination via renal and liver (unlike enalapril).
• Tx: hypertension and CHF
• SE: may cause azotemia, hypotension

Papich

Question 5

Enalapril Maleate

Answer 5

• Vasodilator, Angiotensin-converting enzyme (ACE) inhibitor
• MOA: Inhibits conversion of Ang I to Ang II. Ang II is a potent vasoconstrictor and also stimulates sympathetic stimulation, renal hypertension and synthesis of aldosterone (which causes Na and water retention). ACE inhibitors cause vasodilation and decrease aldosterone induced congestion. Renal eleiminiation (?)
• Tx: Hypertension and CHF, +/- renal disease when GF pressures are too high
• SE: azotemia, hypotension

Papich

Question 6

Spironolactone

Answer 6

• Diuretic
• MOA: potassium-sparing diuretic. Interferes with Na reabsorption in distal renal tubules by competitively inhibiting the actions of aldosterone (aldosterone antagonism). It binds directly to the aldosterone receptor. Acts synergistically with ACE inhibitors
• Tx: hypertension and congestion of CHF
• SE: hyperkalemia (+/- steroid like side effects long term)
• NSAIDS may interfere with action

Papich

Question 7

Dobutamine HCl

Answer 7

• Cardiac Inotropic agent
• MOA: adrenergic agonist. Primarily stimulates myocardial contractility via its effects on Beta 1 receptors. Some action on the alpha receptros may contribute to its action and effects on heart rate. Short 1/2 life (2-3minutes)- so give via CRI.
• Tx: primarily for acute treatment of heart failure. Produces inotropic effect wihtout increasing heart rate.
• SE: may cause tachycardia and ventricular arrhythmias at high doses

**do not mix with alkaline solutions (containing bicarbonate), heparin, cephalosporins or penicillins. Do not give to patients on MOAI

• Monitor HR/EKG while administering
• Dogs: 5-20mcg/kg/min; Cats 2mcg/kg/min (dilute and syringe pump)

Question 8

Dopamine HCl

Answer 8

• Cardiac inotropic agent
• MOA: adrenergic and dopamine agonist. At low doses stimulates the dopamine (D1) recptors (causes renal arterial vasodilation and natriuresis). At moderate dose it stimulates adrenergic receptors and at high doses it acts as an alpha 1 receptor agonist (producing vasoconstriction). Rapid half life- give as CRI
• Tx: Dopamine is used to stimulate myocardium via action of cardiac beta 1 receptors.
• SE: tachycardia and ventricular arrythmias at high doses
• Unstable in alkaline fluids
• Low dose (vasodilation, D1 receptor) 0.5-2mcg/kg/min
• Medium dose (cardiac stimulation, Beta 1 receptor)/Acute heart failure and cardiogenic shock 2-10mcg/kg/min
• High dose (vasoconstriction, alpha-receptor) >10mcg/kg/min

Papich

Question 9

Dobutamine vs Dopamine

Why?

Answer 9

Dobutamine more for heart disease when wanting positive inotrope to increase heart pumping (by Beta 1) without vasoconstriction (i.e. DCM dog where you don’t want to cause vasoconstriction and therefore increase afterload).

Dopamine more for increasing pressure (in non-cardiac related situations), as it not only increases heart pumping (by Beta 1) but also causes vasoconstriction (by alpha) - especially at medium/high dose.

TK

Question 10

Aspirin

Answer 10

• Antithrombotic (mild)
• MOA - inhibition of cyclooxygenase which reduces thromboxane A2 production

FAT CAT study