Lecture 22 - Vasodilators Flashcards
What are the families of drugs used for vasodilation purposes?
NO acting
Calcium Channel Antagonists
PDE5 inhibitors
Alpha 1 Adrenergic antagonists
Drugs within Family: NO acting
Hydralazine
Nitrate
Drugs within Family: Nitrate
Nitroglycerin
Isosorbide dinitrate
Sodium Nitroprusside
Drugs within Family: Calcium channel antagonists
Amlodipine besylate
Diltiazem
Drugs within Family: PDE5 inhibitors
Sildenafil
Drugs within Family: Alpha-1 aderenergic antagonists
Prazosin
What does Gq cause to occur?
Activates PLC
After PLC is activated by Gq what are the downstream effects?
PIP2 –> DAG + IP3
IP3 - dephosphorylated
DAG - broken down
Ca - pumped out
What does DAG go and do once activated?
Stimulate PKC
What does IP3 do and do once it is activated?
Release Ca from intracellular storage
What are three ways that one can relax vascular smooth muscle?
Increase cGMP
decrease intracellular Ca
Increase cAMP in vascular cells
What drugs can increase cGMP?
NO
Nitroprusside
Organic nitrates
PDE 5 inhibitors
What drugs can decrease intracellular Ca?
Calcium channel blcokers
Why is it preferred to have increased cAMP within the vascular cells?
cAMP = inactivation of myosin light chain kinase
Term: Phosphatase
Dephosphorylates MLC
Term: MLCK
Prevents phosphorylation
What can vasodilators do that help some heart failure patients?
Improve CO
– and –
Reduce edema + Effusion
What can drugs that reduce arterolar resistance be used for commonly?
Pulmonary hypertension
What drugs can effect the walls of arteries and/or veins?
ACEi Nitrites Hydralazine CCA-s Alpha-blockers
Vessels affected: ACEi
A = V
Vessels affected: Nitrates
A
Vessels affected: Hydralazine
A
Vessels affected: CCA’s
A a lot
Vessels affected: Alpha-blockers
A = V
What is hydralazine commonly used for?
Mitral valve insufficency
What happens with hyralazine toxicity?
Vomiting + Anorexia + Tachycarida + Sweating +
Ischemic arrhythmia + Decomposition
What hydralazine side effect is seen in all animals besides dogs?
Hypotension
What do Nitrate compounds do chemically?
NO donors
What do nitrates do within the cell?
Decrease the phosphorylation of light chain mysosin
What is nitroglycerin used for?
Pulmonary edema with CHF
How is nitroglycerin administered?
Topically
How is isosorbide dinitrate administered?
Oral
How is sodium nitroprusside administered/
Constant IV
What is sodium nitroprusside used for?
Pulmonary edema
– and –
Emergent hypertensive crisis
What are the two important functions of intracellular calcium?
Triggers muscular contraction
– and –
Pacemake activity
Smooth muscle calcium channels are open to:
B-Adrenergic stimulation
Smooth muscle calcium channels are closed to:
CCA’s
How do CCA’s work?
Orally active
Bind to L-type Ca channels in myocardium vascular SM
What three things will CCA’s cause?
Decrease transmembrane Ca current
Long-lasting relaxation
Decreased cardiac contractility + automaticity + conduction
What other smooth muscle is affected by CCA’s
Bronchiolar + Gastrointestinal + Urterine
What are the major cardiac affects of CCA’s?
Negative inotropic effect
Reduced impulse generation
Slowed AV
Characteristics of amlodipine besylate:
Long lasting
Ca channel blocker
Vasodilation without cardiac effects
What is Amlodipine besylate used for?
Hypertension in cats
What is diltiazem used for?
Hypertrophic cardiomyopathy
– and –
Supraventricular tachycardia
What is different about the metabolism of Diltiazem?
Two active metabolites once it is processed by the liver
What needs to be taken into consideration when giving a patient Diltiazem?
Can be passed through milk
How does sildenafil work?
Decreases the elimination of cGMP = vasodilation
When is sildenafil used?
Pulmonary hypertension in dogs
What is the primary use of prazosin?
Urtheral obtruction in dogs
How does prazosin work?
Reduces NE vasocontriction
What are the adverse effects of prazosin?
Hypotension
Na + Water retension
