PHARMA-ADRENERGIC AGONIST, ANTAGONIST, CHOLINERGIC AND ANTICHOLINERGIC AGENTS

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  • 1. NERVOUS SYSTEM AGENTS ADRENERGIC AGONIST 1
  • 2. ADRENERGIC AGONISTS• Drugs that has effects similar to epinephrine (adrenaline)• Sympathomimetic agentMECHANISM OF ACTION1. Bind to receptors directly – Bind to receptors and copy actions of natural transmitters (catecholamine) 2
  • 3. 3
  • 4. ADRENERGIC AGONISTS2. Promote release of norepinephrine – By acting on sympathetic nervous system to release norepinephrine – Ex that promote receptor activation = amphetamine & ephedrine 4
  • 5. 3. Inhibit norepinephrine uptake – Results in accumulation of norepinephrine in the synaptic cleft and ↑activation of receptors 5
  • 6. ADRENERGIC AGONISTS4. Inhibit activation of epinephrine – Drugs inhibit monoamine oxidase to make more epinephrine available for release 6
  • 7. ADRENERGIC AGONISTS • EFFECTS OF ADRENERGICS AT RECEPTORS 1. Alpha 1 – Located in vascular tissues & smooth muscles 2. Alpha 2 – Located in sympathetic nerve endings 3. Beta 1 receptor – Primarily in the heart 4. Beta 2 – Smooth muscles of lungs – Arterioles of skeletal muscles – Uterine muscle 7
  • 8. ADRENERGIC AGONISTS1. Alpha 1 – Located in vascular tissues & smooth muscles 1. ↑ Force of heart contraction 2. Vasoconstriction = ↑ BP 3. Dilate pupils 4. ↓GI Secretions 5. ↑bladder and prostate contraction 8
  • 9. ADRENERGIC AGONISTS2. Alpha 2 (opposite to alpha1) – Located in sympathetic nerve endings 1. Inhibit norepinephrine release 2. Dilates blood vessels 3. ↓ GI motility 4. ↓ BP3. Beta 1 receptor – Primarily in the heart 1. ↑ Heart rate and force of contraction 2. ↑ secretion of renin 3. ↑ BP 9
  • 10. ADRENERGIC AGONISTS4. Beta 2 – Smooth muscles of lungs – Arterioles of skeletal muscles – Uterine muscle 1. Dilates bronchioles 2. Promote GI and uterine relaxation 3. ↑ Blood sugar thru glycogenolysis 10
  • 11. ADRENERGIC AGONISTS• Alpha & Beta-Adrenergic Agonist – Epinephrine, norepinephrine, dopamine, dobutamine, ephedrine, mephentemine and metaraminol – ACTION: 1. ↑ HR with ↑ myocardial contractility 2. Dilation of bronchi resulting to increased depth and rate 3. ↑ BP due to vasoconstriction 4. Breakdown glucose stores to produce energy 5. Dilation of pupils and ↑ sweating 11
  • 12. Alpha & Beta-Adrenergic Agonist INDICATION: • Tx of hypotensive states or shock PHARMACOKINETICS • Absorbed after injection or passage through mucus membrane • Metabolized in liver • Excreted in urine 12
  • 13. Alpha & Beta-Adrenergic AgonistCONTRAINDICATIONS:• With pheochromocytoma – Systemic overload could be fatal• Ventricular fibrillation – ↑ HR and oxygen consumption caused by these drugs exacerbate symptomsCAUTION – Any kind of peripheral vascular disease – exacerbate by systemic vasoconstriction 13
  • 14. ALPHA-SPECIFIC ADRENERGIC AGONIST • Bind primarily to alpha receptors • Drugs: – Phenylephrine – Midodrine – Clonidine 14
  • 15. ALPHA-SPECIFIC ADRENERGIC AGONIST INDICATIONS: • Clonidine = tx for HPN • Phenylepinephrine – Can be found in cold and allergy medications – Cause vasoconstriction to decrease swelling & congestion associated with rhinitis • Midodrine = tx orthostatic hypotension who do not respond to other therapies. 15
  • 16. ALPHA-SPECIFIC ADRENERGIC AGONIST PHARMACOKINETICS • Peak level in 20-45min • Distributed in body • Metabolized in liver • Excreted in urine CONTRAINDICATIONS: • Severe hypotension and tachycardia • Narrow angle glaucoma • pregnancy 16
  • 17. BETA-SPECIFIC ADRENERGIC AGONISTS ACTION: – ↑ HR, conductivity & contractility – Bronchodilation – ↑ Blood flow to skeletal muscles – Relaxation of uterus INDICATIONS: – Bronchial asthma & pulmonary conditions – Isoproterenol = for shock & ventricular arrhythmias • Stimulate cardiac activity and conduction 17
  • 18. CONTRAINDICATIONS• Isoproterenol is contraindicated in: – + allergy – Pulmonary hypertension – During anesthesia with halogenated hydrocarbon – Eclampsia – Uterine hemorrhage – Intrauterine death 18
  • 19. CAUTION• With diabetes• Thyroid disease• Vasomotor problems• Degenerative heart disease• Hx of stroke 19
  • 20. ADRENERGIC ANTAGONISTALPHA & BETA-SPECIFIC BLOCKERSACTION: – Competitively block the effects of norepinephrine at both alpha & beta receptors – Result to ↓blood pressure, ↓ PR and ↑renal perfusion 20
  • 21. ALPHA & BETA-SPECIFIC BLOCKERSINDICATION = HPNCONTRAINDICATION:• Not recommended <18yo• Bradycardia/heart blocks• Asthma, shock or heart failure• Pregnancy and lactationCAUTION:• DM pt as it can: – mask symptoms of hyperglycemia and hypoglycemia – Constrict peripheral vessels =reduced blood flow 21
  • 22. ALPHA-SPECIFIC BLOCKERSACTION: – Block postsynaptic alpha1 receptor resulting to ↓ in vascular tone and vasodilation.INDICATION: – BENIGN PROSTATIC HYPERTROPHY – HPN 22
  • 23. BETA-SPECIFIC BLOCKERSACTION: – Blocks beta receptors in heart and in juxtaglomerular apparatus – ↓HR, contractility and excitabilityINDICATION: – Cardiovascular problem • HPN, angina, migraine and HA • Prevent reinfarction 23
  • 24. 24
  • 25. CHOLINERGIC AGONISTS PARASYMPATHOMIMETIC CHOLINERGIC STIMULANTS CHOLINOMIMETICS 25
  • 26. CHOLINERGIC AGONISTS• Stimulate PNS• Copy the action of acetylcholineAcetylcholine – Neurotransmitter located at the ganglions and parasympathetic terminal nerve endings that acts on the receptors found in organs, tissues and glands – Stimulate skeletal muscle contraction 26
  • 27. CHOLINERGIC AGONISTS2 TYPES OF CHOLINERGIC RECEPTORS: 1. MUSCARINIC • Stimulate smooth muscles • Slow HR 2. NICOTINIC • Affects skeletal muscles 27
  • 28. CHOLINERGIC AGONISTSDIRECT ACTING CHOLINERGICSACTION: – React directly with receptor sites to cause the same reaction as acetylcholine – Stimulate muscarinic receptors within the PNS 28
  • 29. CHOLINERGIC AGONISTSDIRECT ACTING CHOLINERGICSACTION:PNS effects – ↓HR and myocardial contractility – Vasodilation – Bronconstriction – ↑bronchial secretions – ↑ GI activity – ↑ bladder tone – Relaxed GI sphincter – Papillary constriction 29
  • 30. CHOLINERGIC AGONISTSDIRECT ACTING CHOLINERGICSINDICATION: – OPTHALMIC AGENTS – INCREASE URINARY EXCRETION 30
  • 31. CHOLINERGIC AGONISTSINDIRECT-ACTING CHOLINERGICSACTIONS• React chemically with acetylcholinesterase in synaptic cleft to prevent breakdown of acetylcholine(Ach)• Result: Ach is released from presynaptic nerve remains in the area and accumulates, stimulating the Ach receptors• Permits skeletal muscle stimulation, which ↑ force of muscular contraction 31
  • 32. CHOLINERGIC AGONISTSINDICATION:• Myasthenia gravis• Glaucoma• Alzheimer’s diseaseCONTRAINDICATION:• Bradycardia• Intestinal/urinary obstruction• Pregnancy or lactation 32
  • 33. ANTICHOLINERGICS 33
  • 34. ANTICHOLINERGICS• Block the Ach receptors at muscarinic cholinergic receptor sites, responsible for mediating the effect of PNS• Depress salivation and bronchial secretions, dilate bronchi, relax GI & GU tracts, relax pupils 34
  • 35. ANTICHOLINERGICSINDICATION• ↓ Secretions before anesthesia• Tx Parkinsonism• Restore cardiac rate & BP after vagal stimulation during surgery• Relieve bradycardia• Relieve pylorospasm & hyperactive bowel• Relax bladder detrusor muscles• Peptic ulcer• Control of rhinorrhea• Antidote for cholinergic drugs• Ophthalmic agent to cause mydriasis 35