1. NERVOUS SYSTEM AGENTS
ADRENERGIC AGONIST
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2. ADRENERGIC AGONISTS
• Drugs that has effects similar to epinephrine
(adrenaline)
• Sympathomimetic agent
MECHANISM OF ACTION
1. Bind to receptors directly
– Bind to receptors and copy actions of natural transmitters
(catecholamine)
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4. ADRENERGIC AGONISTS
2. Promote release of norepinephrine
– By acting on sympathetic nervous system to release
norepinephrine
– Ex that promote receptor activation = amphetamine &
ephedrine
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5. 3. Inhibit norepinephrine uptake
– Results in accumulation of
norepinephrine in the synaptic
cleft and ↑activation of
receptors
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6. ADRENERGIC AGONISTS
4. Inhibit activation of epinephrine
– Drugs inhibit monoamine oxidase to make more
epinephrine available for release
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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
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8. ADRENERGIC AGONISTS
1. 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
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9. ADRENERGIC AGONISTS
2. Alpha 2 (opposite to alpha1)
– Located in sympathetic nerve endings
1. Inhibit norepinephrine release
2. Dilates blood vessels
3. ↓ GI motility
4. ↓ BP
3. Beta 1 receptor
– Primarily in the heart
1. ↑ Heart rate and force of contraction
2. ↑ secretion of renin
3. ↑ BP
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10. ADRENERGIC AGONISTS
4. 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
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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
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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
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13. Alpha & Beta-Adrenergic Agonist
CONTRAINDICATIONS:
• With pheochromocytoma
– Systemic overload could be fatal
• Ventricular fibrillation
– ↑ HR and oxygen consumption caused by these drugs
exacerbate symptoms
CAUTION
– Any kind of peripheral vascular disease – exacerbate
by systemic vasoconstriction
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14. ALPHA-SPECIFIC ADRENERGIC AGONIST
• Bind primarily to alpha receptors
• Drugs:
– Phenylephrine
– Midodrine
– Clonidine
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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.
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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
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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
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18. CONTRAINDICATIONS
• Isoproterenol is contraindicated in:
– + allergy
– Pulmonary hypertension
– During anesthesia with halogenated hydrocarbon
– Eclampsia
– Uterine hemorrhage
– Intrauterine death
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19. CAUTION
• With diabetes
• Thyroid disease
• Vasomotor problems
• Degenerative heart disease
• Hx of stroke
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20. ADRENERGIC ANTAGONIST
ALPHA & BETA-SPECIFIC BLOCKERS
ACTION:
– Competitively block the effects of norepinephrine at
both alpha & beta receptors
– Result to ↓blood pressure, ↓ PR and ↑renal
perfusion
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21. ALPHA & BETA-SPECIFIC BLOCKERS
INDICATION = HPN
CONTRAINDICATION:
• Not recommended <18yo
• Bradycardia/heart blocks
• Asthma, shock or heart failure
• Pregnancy and lactation
CAUTION:
• DM pt as it can:
– mask symptoms of hyperglycemia and hypoglycemia
– Constrict peripheral vessels =reduced blood flow
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22. ALPHA-SPECIFIC BLOCKERS
ACTION:
– Block postsynaptic alpha1 receptor resulting to ↓
in vascular tone and vasodilation.
INDICATION:
– BENIGN PROSTATIC HYPERTROPHY
– HPN
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23. BETA-SPECIFIC BLOCKERS
ACTION:
– Blocks beta receptors in heart and in
juxtaglomerular apparatus
– ↓HR, contractility and excitability
INDICATION:
– Cardiovascular problem
• HPN, angina, migraine and HA
• Prevent reinfarction
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25. CHOLINERGIC AGONISTS
PARASYMPATHOMIMETIC
CHOLINERGIC STIMULANTS
CHOLINOMIMETICS
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26. CHOLINERGIC AGONISTS
• Stimulate PNS
• Copy the action of acetylcholine
Acetylcholine
– 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
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27. CHOLINERGIC AGONISTS
2 TYPES OF CHOLINERGIC RECEPTORS:
1. MUSCARINIC
• Stimulate smooth muscles
• Slow HR
2. NICOTINIC
• Affects skeletal muscles
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28. CHOLINERGIC AGONISTS
DIRECT ACTING CHOLINERGICS
ACTION:
– React directly with receptor sites to cause the same
reaction as acetylcholine
– Stimulate muscarinic receptors within the PNS
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29. CHOLINERGIC AGONISTS
DIRECT ACTING CHOLINERGICS
ACTION:
PNS effects
– ↓HR and myocardial contractility
– Vasodilation
– Bronconstriction
– ↑bronchial secretions
– ↑ GI activity
– ↑ bladder tone
– Relaxed GI sphincter
– Papillary constriction
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30. CHOLINERGIC AGONISTS
DIRECT ACTING CHOLINERGICS
INDICATION:
– OPTHALMIC AGENTS
– INCREASE URINARY EXCRETION
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31. CHOLINERGIC AGONISTS
INDIRECT-ACTING CHOLINERGICS
ACTIONS
• 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
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32. CHOLINERGIC AGONISTS
INDICATION:
• Myasthenia gravis
• Glaucoma
• Alzheimer’s disease
CONTRAINDICATION:
• Bradycardia
• Intestinal/urinary obstruction
• Pregnancy or lactation
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33. ANTICHOLINERGICS
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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
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35. ANTICHOLINERGICS
INDICATION
• ↓ 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
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