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Adrenergic drugs.
- 1. Adrenergic drug Md. Kawsar 8thBatch Department of Pharmacy
- 2. Adrenergic nervous system Adrenergicnervous system is a group of organs and nerves in which adrenaline and/or noradrenaline are released as neurotransmitters. Adrenergic nerve release neurotransmitters: noradrenaline, adrenaline, dopamine and produce their effect.
- 3. Adrenergic drugs Drugs thatproduce similar effects to those produced by sympathetic nervous system thus they are also called sympathomimetic drugs. It may refer to something which is susceptible to epinephrine or similar to substances, such as biological receptor especially adrenergic receptor. A great number of drugs available which can affect adrenergic receptors e.g. dopamine, noradrenaline, adrenaline, isoprenaline etc.
- 4. Adrenergic receptors Adrenergic receptorsare broadly classified into three groups i. Alpha receptor: there are two subclasses of alpha receptor – - α-1 receptor - α-2 receptor ii. Beta receptor: β-receptors are subdivided into – - β-1 receptor - β-2 receptor - β-3 receptor iii. Dopamine receptor: Dopamine receptors are of two types – - D-1 receptor - D-2 receptor
- 5. Classification of adrenergicdrugs A. According to mode of action: i. Directly acting – adrenaline, noradrenaline, dopamine, isoprenaline. ii. Indirectly acting – amphetamine, methamphetamine, iii. By both mechanism – ephedrine, metaraminol. B. According to receptor selectivity: i. α1 agonist – methoxamine, phenylepeneprine. ii. α2 agonist – clonidine, α-methyl noradrenaline. iii. Both α1-α2 agonist - adrenaline, noradrenaline.
- 6. iv. β1 agonist– prenalterol, dobutamine. v. β2 agonist – salbutamol, terbutaline. vi. Both β1–β2 agonist – adrenaline, isoproterenol. vii.Both α - β agonist – adrenaline, ephedrine. C. According to chemical nature: i. Catecholamines – adrenaline, noradrenaline, dopamine, isoprenaline. ii. Noncatecholamines – ephedrine, amphetamine, metaraminol.
- 7. D. According totherapeutic effect: i. Vasoconstrictor – adrenaline, noradrenaline, ephedrine, metaraminol. ii. Vasodilator – dopamine, isoprenaline. iii. Bronchodilator – salbutamol, terbutaline. iv. CNS stimulant – amphetamine, methamphetamine. v. Cardiac stimulant – adrenaline, isoprenaline, prenalterol. vi. Nasal decongestant – ephedrine, oxymethazoline. vii.Uterine relaxants – Nylidrine, salbutamol.
- 8. Pharmacological action ofAdrenergic drugs: - Increase heart rate, increase force of contraction of heart, increase tissue perfusion. - α agonist causes vasoconstriction - β agonist causes vasodilation - β2 agonist causes bronchial dilation - Inhibit noradrenaline release. This is called auto inhibitory feedback mechanism noradrenaline release.
- 9. Indication of Adrenergicdrugs: - Heart block. - Treatment of asthma e.g. salbutamol. - Hypertension, cardiogenic shock. - Used for prolongation of local anesthetic action by vasoconstriction e.g. adrenaline. - To control local bleeding e.g. adrenaline. - As nasal decongestant e.g. oxymethaoline. - Inhibition of uterine contraction e.g. nylidrine.
- 10. Adrenaline: Epinephrine or adrenalineis a sympathomimetic catecholamine. The chemical name of epinephrine is 3, 4- Dihydroxy phenyl-α-2methylamino ethanol.
- 11. Mechanism of action: theaction of adrenaline is receptor mediated. It produces both excitatory and inhibitory effects. Excitatory effects due to stimulation of α receptor except the intestine where it is inhibitory. Inhibitory effect due to stimulation of β receptor except the heart where it is excitatory. Pharmacological action: On heart – increase force of contraction, heart rate, conductivity, automaticity. On blood pressure – increase systemic blood pressure, decrease diastolic bold pressure, decrease total peripheral resistant, increase CO.
- 12. On blood vessel– dilation of coronary and muscular bold vessels, contraction of visceral and cutaneous blood vessels. On respiratory system – bronchodilation, stimulation of respiration. On eye – mydriasis, exophthalamus, reduce intra-ocular pressure. On CNS – it doesn’t cross BBB effectively. On metabolism – increase blood sugar level, increase lactic acid, promote release of fatty acid from adipose tissue.
- 13. Indication: i. Treatment ofallergic reactions ii. Tachycardia iii. Hypotension iv. Convulsion v. Addition with local anesthesia. Contraindication: o Pulmonary edema o Metabolic acidosis o Hypertension
- 14. o Ischemic heartdisease o Cardiac arrhythmia o Hyperthyroidism. Adverse effect: i. Agitation ii. Throbbing headache, tremor iii. Weakness, dizziness, pallor iv. Respiratory insufficiency v. Cerebral hemorrhage
- 15. Noradrenaline: It is animportant neurotransmitter both in peripheral and central nervous system. The chemical name of norepinephrine or noradrenaline is 3, 4-Dihydroxy phenyl-α-amino ethanol. It is the precursor of adrenaline.
- 16. Mechanism of action: Noradrenalineacts by binding with α1, α2 and β1 adrenoceptors. At almost has no activity on β2 receptors. Pharmacological action: Systolic pressure – increased Diastolic pressure – increased Mean pressure – increased T.P.R. – increased Heart rate – decreased or unchanged
- 17. Cardiac output –unchanged or increased Coronary blood flow – increased On CNS – little stimulation Indication: i. Shock ii. Topical hemostasis iii. Nasal decongestant iv. Addition with local anesthetic.
- 18. Adverse effect: i. Lossof appetite. ii. Anxiety iii. Irregular heartbeats iv. Shortness of breath v. vi. Headache. Contraindication: i. Hyperthyroidism ii. Pregnancy iii. coronary thrombosis.
- 19. Clonidine: Clonidine is aα2 adrenoceptor agonist, lowers blood pressure by decreasing the levels of certain chemicals in your blood. This allows your blood vessels to relax and your heart to beat more slowly and easily.
- 20. Mechanism of action:Clonidine treats high blood pressure by stimulating α2-receptors in the brain, which decreases peripheral vascular resistance, lowering blood pressure. It has specificity towards the presynaptic α2-receptors in the vasomotor center in the brainstem. This binding decreases presynaptic calcium levels, thus inhibiting the release of norepinephrine. The net effect is a decrease in sympathetic tone. It has also been proposed that the antihypertensive effect of clonidine is due to agonism on the I1- receptor (imidazoline receptor), which mediates the sympatho- inhibitory actions of imidazolines to lower blood pressure.
- 21. Pharmacological action: CNS –supress sympathetic outflow thus decrease blood pressure. Periphery – supress noradrenaline release thus decrease blood pressure. CVS – Decrease HR and CO Blood vessel – reduction of capacitance vessels. Reduce in peripheral resistance, decrease blood pressure. Indication: i. Hypertension ii. Prophylaxis of migraine iii. Diagnosis of phaechromocytoma.
- 22. Adverse effect: i. Sedation ii.Dry mouth iii. Drowsiness iv. Rebound hypertension v. Headache vi. Fatigue.
- 23.