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YEAR 2 PHARMACOLOGY & THERAPEUTICS ESSENTIAL DRUG LIST

YEAR 2 PHARMACOLOGY & THERAPEUTICS ESSENTIAL DRUG LIST. Alexandra Burke-Smith. 1. Drugs and the Autonomic Nervous System. Overview of the ANS. Sympathetic NS = “fight or flight”, Parasympathetic NS = “rest + digest” NT = Ach + NA Ach Receptors: nicotinic + muscarinic cholinoceptors

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YEAR 2 PHARMACOLOGY & THERAPEUTICS ESSENTIAL DRUG LIST

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  1. YEAR 2 PHARMACOLOGY & THERAPEUTICS ESSENTIAL DRUG LIST Alexandra Burke-Smith

  2. 1. Drugs and the Autonomic Nervous System

  3. Overview of the ANS Sympathetic NS = “fight or flight”, Parasympathetic NS = “rest + digest” NT = Ach + NA Ach Receptors: nicotinic + muscarinic cholinoceptors Nicotinic = ionotrophic (ligand-gated ion channel) Muscarinic – metabotrophic (G-protein) Muscarinic subtypes: M1 – neural (excitatory) M2 – cardiac (inhibitory) M3 – exocrine (excitatory) NA receptors: adrenoceptors A1 > PLC > IP3 + DAG > PKC + Ca2+ A2 > cAMP > PKA B1 > cAMP > PKA B2 > cAMP > PKA

  4. Cholinomimetics • “drugs which mimic the action of Acetylcholine (Ach agonists)” • Principally mimic parasympathetic NS • Directly acting: choline esters + alkaloids that have agonistic action at Ach receptors • Indirectly acting: anticholinesterases that potentiate the action of Ach; preventing its breakdown by inhibiting acetylcholinesterase and/or butyrylcholinesterase (plasma ezyme) • Reversible = alkaloid carbamyl esters • Irreversible = organophosphate compounds

  5. Cholinoceptor Antagonists • “drugs which show affinity but no efficacy at Ach receptors, thus preventing agonists from transducing a response and activating intracellular signalling pathways”

  6. Sympathomimetics • SNS agonists • Act on adrenoreceptors of post-ganglionic SNS neurons • Directly acting: mimic actions of NA/A by binding and stimulating adrenoceptors – used principally for actions in CVS, eyes + lungs • Indirectly acting: act at the adrenergic nerve terminal as opposed to adrenoceptor

  7. SNS Antagonists • Act with antagonistic action at adrenoceptors • These may be: • Non-selective • Non-selective alpha • Alpha 1 selective • Non selective beta • Beta 1 selective

  8. Neuromuscular Blocking Drugs • Drugs which act at the NMJ To prevent depolarisation of the motor end-plate • Non-depolarising: competitive antagonsts • Depolarising: agonists

  9. 2. Drugs and the Cardiovascular System

  10. RAAS • RAAS = renin angiotensin aldosterone system • Primarily responsible for fluid + BP regulation • Drugs interfering with RAAS: • ACE inhibitors • Angiotensin II receptor antagonists (ARB) • Renin inhibitors, egAliskiren (no significant clinical experience)

  11. Calcium Antagonists • Rise in intracellular calcium key step in excitation-contraction coupling in both cardiac and vascular myocytes • Involves L-type voltage-dependent calcium channel • 2 classes of calcium channel blockers (CCBs) • Rate limiting (bind to IC domain of receptor; exert both cardiac and smooth muscle effects) • Non-rate slowing (bind to EC domain of receptor; exerts only smooth muscle action), eg amlodipine

  12. Beta Blockers • Sympathetic neurons innervating cardiac muscle release NA on depolarisation • NA acts on B1 receptors on cardiac myocytes, to increase heart rate, contractility and excitability • Competitive antagonists, ie beta blockers, thus tend to have a negative chronotropic and ionotropic effect

  13. Organic Nitrates + Related Agents • Organic nitrite is absorbed (particularly in SMC), where it undergoes degradation into nitrite free radical, then converted to nitric oxide • Nitric oxide is an endogenous vasodilator; it acts on guanylatecyclase to increase cGMP production • cGMP then acts to vasodilate the smooth muscle

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