PHARMA-ADRENERGIC AGONIST, ANTAGONIST, CHOLINERGIC AND ANTICHOLINERGIC AGENTS

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PHARMA-ADRENERGIC AGONIST, ANTAGONIST, CHOLINERGIC AND ANTICHOLINERGIC AGENTS

  1. 1. NERVOUS SYSTEM AGENTS ADRENERGIC AGONIST 1
  2. 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
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  4. 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. 5. 3. Inhibit norepinephrine uptake – Results in accumulation of norepinephrine in the synaptic cleft and ↑activation of receptors 5
  6. 6. ADRENERGIC AGONISTS4. Inhibit activation of epinephrine – Drugs inhibit monoamine oxidase to make more epinephrine available for release 6
  7. 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. 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. 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. 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. 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. 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. 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. 14. ALPHA-SPECIFIC ADRENERGIC AGONIST • Bind primarily to alpha receptors • Drugs: – Phenylephrine – Midodrine – Clonidine 14
  15. 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. 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. 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. 18. CONTRAINDICATIONS• Isoproterenol is contraindicated in: – + allergy – Pulmonary hypertension – During anesthesia with halogenated hydrocarbon – Eclampsia – Uterine hemorrhage – Intrauterine death 18
  19. 19. CAUTION• With diabetes• Thyroid disease• Vasomotor problems• Degenerative heart disease• Hx of stroke 19
  20. 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. 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. 22. ALPHA-SPECIFIC BLOCKERSACTION: – Block postsynaptic alpha1 receptor resulting to ↓ in vascular tone and vasodilation.INDICATION: – BENIGN PROSTATIC HYPERTROPHY – HPN 22
  23. 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
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  25. 25. CHOLINERGIC AGONISTS PARASYMPATHOMIMETIC CHOLINERGIC STIMULANTS CHOLINOMIMETICS 25
  26. 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. 27. CHOLINERGIC AGONISTS2 TYPES OF CHOLINERGIC RECEPTORS: 1. MUSCARINIC • Stimulate smooth muscles • Slow HR 2. NICOTINIC • Affects skeletal muscles 27
  28. 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. 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. 30. CHOLINERGIC AGONISTSDIRECT ACTING CHOLINERGICSINDICATION: – OPTHALMIC AGENTS – INCREASE URINARY EXCRETION 30
  31. 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. 32. CHOLINERGIC AGONISTSINDICATION:• Myasthenia gravis• Glaucoma• Alzheimer’s diseaseCONTRAINDICATION:• Bradycardia• Intestinal/urinary obstruction• Pregnancy or lactation 32
  33. 33. ANTICHOLINERGICS 33
  34. 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. 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

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