Common Receptors and enzymes

Common receptors, substrates, enzymes, tarets for medications, and drug examples

Mascaranic receptor

Endogenous substrate: Acetylcholine

Agonist Action: Increase SLUDD

Drug Agonists: Pilocarpine, Bethanechol

Antagonist Action: Decrease SLUDD.

Drug Antagonists: Atropine, oxybutynin

Nicotine receptor

Endogenous substrate: Acetylcholine

Agonist Action: Increase heart rate and blood pressure.

Drug Agonists: Nicotine

Antagonist Action: Neuromuscular blockade

Drug Antagonists: Neuromuscular blockers like Rockuronium

Alpha-1

Endogenous substrate: Epi, and norepi.

Agonist Action: Smooth muscle vasoconstriction, increase BP

Drug Agonists: Phenylephrine, dopamine (Dose dependent, high (>10mcg/kg/min))

Antagonist Action: Smooth muscle vasodilation, decrease BP

Drug Antagonists: Alpha-One blockers (doxazosin, Carvedilol, Phentolamine)

Alpha-2

Endogenous substrate: EPI, norepi

Agonist Action: decrease release of epinephrine and or epinephrine, decrease BP, HR

Drug Agonists: Clonidine, Brimonidine

Antagonist Action: Increase BP, HR.

Drug Antagonists:

Beta -1

Endogenous substrate: Epi, nor EPI.

Agonist Action: increase Myocardial contractility, CO, HR

Drug Agonists: Dobutamine, isoproterenol, dopamine (5-10mcg/kg/min).

Antagonist Action: Decrease CO, HR.

Drug Antagonists: Beta-1 selective blockers (Metoprolol) And nonselective beta- blockers Randall all, Carvedilol, etc)

Beta -2

Endogenous substrate: Epinephrine

Agonist Action: Bronchodilation

Drug Agonists: Albuterol, Terbutaline, isoproterenol.

Antagonist Action: Bronco constriction

Drug Antagonists: nonselective beta blockers. (Propranolol, carvedilol)

Dopamine

Endogenous substrate: Dopamine

Agonist Action: Many, including renal, cardiac, and CNS effects.

Drug Agonists: Levodopa, pramipexole

Antagonist Action: Many, including renal, cardiac, and CNS effects.

Drug Antagonists: Hey, Cortana 1st generation antipsychotics. (E dot G dot. Come out Haloperidol

Serotonin

Endogenous substrate: Serotonin

Agonist Action: Many, including platelet, GI, and psychiatric effects.

Drug Agonists: Triptans EG Sumatriptan

Antagonist Action: Many, including platelet, GI, and psychiatric effects.

Drug Antagonists:

Acetylcholinesterase

Endogenous effects: Breaks down acetylcholine.

Drug examples: Acetylcholinesterase inhibitors: Donepezil, Rivastigmine, Galantamine.

Drug action: Block acetylcholinesterase, resulting in increased ACH levels; used to treat Alzheimer's disease.

Angiotensin-converting enzyme. (ACE)

Endogenous effects: Convert angiotensin one to angiotensin 2. (A potent vasoconstrictor)

Drug examples: ACE inhibitors (eg, lisinopril, ramipril.)

Drug action: Inhibit production of angiotensin II, resulting in decreased vasoconstriction and decreased aldosterone secretion; used to treat hypertension, heart failure, and kidney disease.

Catechol - O - methyltransferase (COMT)

Endogenous effects: Breaks down catecholamines (e.g. DA, NE, EPI 5 - HT.)

Drug examples: COMT inhibitor: Entacapone

Drug action: Block COMT enzyme to prevent peripheral breakdown of levodopa, resulting in increased duration of action of levodopa; used to treat Parkinson's disease.

Cyclooxygenase (COX)

Endogenous effects: Converts arachidonic acid to prostaglandins (cause inflammation). And Thromboxane a- 2 (causes platelet aggregation).

Drug examples: NSAIDs (EG, Aspirin, Ibuprofen.)

Drug action: Block cox enzymes decrease prostaglandins and thromboxane A2. Used to treat pain and reduce inflammation/platelet activation aggregation (Aspirin).

Monoamine oxidase (MAO)

Endogenous effects: Breaks down catecholamines (e.g DAE, NE, EPI, 5-HT)

Drug examples: Phenylzene, Isocarboxazid, tranylcypromine, Selegiline, Rasagiline

Drug action: Block MAO, which increases catecholamine levels, is used to treat depression.

If catecholamines increase too much, due to addictive effects from other drugs or foods, toxic effects can occur, such as hypertensive crisis or serotonin syndrome.

Phosphodiesterase (PDE)

Endogenous effects: Breaks down cyclic guanosine monophosphate. (cGMP)

Drug examples: PDE5 inhibitors. (e.g. Sildenafil, Tadalafil)

Drug action: Competitively binds the same active site as CGMP on the PDE 5 enzyme, preventing the breakdown of CGMP and prolonging smooth muscle relaxation. The arteries of the penis; used to treat erectile dysfunction.

Vitamin K epoxide reductase.

Endogenous effects: Converts vitamin K to the active form required for the production of select clotting factors.

Drug examples: Warfarin

Drug action: Blocks vitamin K epoxide reductase enzyme, which decreases production of clotting factors. II, VII, IX, and X; used to treat or prevent blood clots.

Xanthine oxidase

Endogenous effects: Breaks down hypoxanthine into xanthine, and then xanthine into uric acid.

Drug examples: Xanthine oxidase inhibitor: Allopurinol.

Drug action: Blocks xanthine oxidase enzyme, which decreases uric acid production; used to prevent gout attacks.