Agonists, Antagonists, Antagonism On Receptors | Sympathomimetics | RAAS Drugs Flashcards
Agonists, Antagonists, Antagonism on receptors
Agonists: Agents that mimic the activity of a receptors endogenous activator and produces its known response [response itself could be a stimulating or an inhibiting one, however the agent induces conformational changes, downstream signalling and produces its effects]
Agonists can be:
- Full agonists
- Partial agonists
- Inverse agonists [agents that bind to consitutively active/alway active without ligand receptors and produce a negative intrinsic effect; Receptor undergoes changes as if its endogenous agent is bound to it]
Antagonists: Agents that bind to a receptor and prevent its function by inactivating it [either conformationally or by not activating the receptor by occupying the binding site] and produce no function [absence of function]
Antagonists can be:
- Competitive
- Non-competitive
Sympathomimetics
Agents and drugs that mimic the activity of Norepinephrine, Epinephrine and Dopamine in the Sympathetic Nervous system effector organs or postganglionic neurons using catecholamines as neurotransmitters
Direct acting Adrenoreceptor agonists:
- Phenylephrine [Alpha-1 selective]
- Clonidine, Alpha-Methyldopamine [Alpha-2 selective]
- Norepinephrine [Alpha nonselective]
- Dobutamine [Beta-1 selective]
- Albuterol, Terbutaline [Beta-2 selective]
- Isoproterenol [Beta nonselective]
- Epinephrine [Dose dependent: Low - Beta nonselective, Medium - Beta and Alpha-1, High - Alpha nonselective]
Dopamine Agonist:
- Tenoldopam
Indirect acting Adrenoreceptor agonists:
- MAOi
- COMTi
- Tyramine
- Amphetamines
- Ephedrine
- Cocaine, TCA antidepressants
- Mirtazapine [Alpha-2 blockers]
State functions based on receptor activity knowledge
RAAS drugs
ACEi [Captopril, Lisinopril]
ARBs [Losartan, Telmisartan, Valsartan]
Renin Inhibitors [Aliskiren]
Aldosterone antagonists [Spironolactone]
Main uses: Mild to moderate HTN, CHF, Diabetic nephropathy
