Pharmacology For Dental Students 2024-2025 PDF

Pharmacology For The Third Year Dental students Sphinx University BY Assoc. Prof. Mohamed Mostafa Elbadr 2024-2025  Types of adrenergic receptors (1) æ 1- adrenergic receptors: Most of vascular smooth muscles causing...

Pharmacology For The Third Year Dental students Sphinx University BY Assoc. Prof. Mohamed Mostafa Elbadr 2024-2025  Types of adrenergic receptors (1) æ 1- adrenergic receptors: Most of vascular smooth muscles causing contraction. Genitourinary smooth muscles causing contraction of trigone, and sphineter Pupillary dilator muscle of eye causing contraction (active mydriasis) Liver causing glycogenolysis, and gluconeogenesis Intestine causing relaxation (2) æ 2 - adrenergic receptors: Vascular smooth muscles causing contraction B-cell of pancreas causing decrease in insulin secretion Presynaptic nerve terminals causing decrease in transmitter release (NE). (3) B1 - adrenergic receptors: Heart causing increase in force of contraction, heart rate and A-V nodal conduction. (4) B2 - adrenergic receptors: Vascular, genitourinary, intestinal, and bronchial smooth muscles causing relaxation. Liver causing glycogenolysis, and gluconeogenesis. B-cell of pancreas causing increase in insulin secretion (5) B3 - adrenergic receptors: Adipose tissues causing lipolysis due to activation of triglyceride lipase. Classifications of sympathomimetics (adrenergic agonists) (1) Catecholamines (contain catechol ring) All are ineffective orally. a) Endogenous: epinephrine, norepinephrine, b) Non-endogenous: dobutamine. (2) Selective B2-agonists: Salbutamol Formoterol Salmeterol. (3) Selective æ1-agonists: - Phenylephrine. (4) Selective æ2- agonists: - α-Methyldopa. (5) Indirect acting sympathomimetics: - Amphetamine  (1)Epinephrine (EP) Mechanism of action It acts by direct binding to all types of adrenergic receptors (æ , B) and activates them. Therapeutic uses 1- Local hemostatic to control bleeding as in epistaxis, bleeding after tooth extraction. 2- With local anesthetic as it causes vasoconstriction so it decreases systemic absorption of anesthetic agent , increases duration of action of anesthetic and decreases bleeding (cocaine does not need EP, as it has vasoconstrictor effect). 3- Sudden cardiac arrest during anesthesia, and hypersensitive carotid sinus as EP intracardiac can be used. 4- Complete heart block. 5- Acute anaphylactic shock: S.C. EP is the drug of choice as it can treat hypotension, bronchospasm, and laryngeal edema. 6- Acute bronchial asthma: EP can be used S.C. or by inhalation as it causes bronchodilation and reduces pulmonary congestion, and edema. 7- Local in the eye in treatment of open angle glaucoma Side effects (1) CVS: tachycardia, palpitation, and hypertension. In severe cases: arrhythmia, angina pectoris, and cerebral hemorrhage. (2) CNS: nervousness, tremors, and headache.  ( 2 ) Norepinephrine Therapeutic uses: -It is used in treatment of hypotension as in shock, used by IV infusion. (3) Dobutamine It is a selective B1-agonist. It is used as short term treatment for acute heart failure  Selective B2-adrencrgic agonists Classifications & uses 1) Drugs used in asthma: a) Short acting (duration 3-6 h). -Salbutamol -Used orally, and by inhalation in chronic, and acute asthma, and parenterally in status asthmatics. b) Long acting (duration 12h) -Salmeterol (used by inhalation, has slow onset, so used in chronic as maintenance treatment of asthma and not suitable in acute asthma). -Formoterol as salmeterol but has rapid onset, so can be used in acute asthma. Side effects: 1- Tremors 2-Tolerance 3- Tachycardia.  Selective æ1 -adrenergic agonists (1) Phenylephrine: Uses: Hypotension as during spinal anesthesia. Nasal decongestant. Eye decongestant. Mydriatic in the eye.  Selective æ2 -adrenergic agonists (1) α- methyl dopa Therapeutic uses: Hypertension (better with diuretics). - Treatment of hypertension during pregnancy.  Indirect acting agonists Mechanism of action -They act by releasing of norepinephrine from sympathetic nerve endings.  Amphetamine Pharmacological actions: - Powerful CNS stimulant a) Psychic stimulant action: - Elevates the mood, increases ability to concentrate, produces self-confidence and euphoria. b) Antifatigue action c) Analgesic action d) Appetite suppressant effect Therapeutic uses: 1- Narcolepsy: (attacks of sleep occur suddenly under unsuitable conditions). 2- Obesity as has anorectic effect must be used with dietary restrictions. 3- Attention deficit hyperactivity disorder (ADHD). -It occur in children with excessive motor activity, difficult in attention Therapeutic uses of sympathomimetics in Dentistry 1- Vasoconstrictor drugs as epinephrine and levonordefrin are combined with local anesthetics especially with infiltration anesthesia Advantages: 1- Decrease the absorption of local anesthetic, so increase the duration of action. -The duration of action of lidocaine 2% when used alone is 44-100 minutes -If lidocaine is combined with epinephrine in a concentration of 1:1.000.000 the duration will be increased to 57-130 minutes. -If lidocaine is combined with epinephrine in a concentration of 1:750.000 the duration will be increased to 67-145 minutes. -If lidocaine is combined with epinephrine in a concentration of 1:250.000 the duration will be increased to 90-175 minutes. -If lidocaine is combined with epinephrine in a concentration of 1:50.000 the duration will be increased to 90-210 minutes. But repeated injection of this concentration may cause tissue necrosis and microscaring 2- Decrease systemic absorption of local anesthetics, so decrease their systemic toxicity. 3- Vasoconstriction of blood vessels, so decrease the bleeding (bloodless field of operation).  Disadvantages: 1- Systemic absorption of the vasoconstrictor drug may occur leading to systemic side effects, so this combination must be used carefully in presence of cardiovascular diseases. 2-Tissue hypoxia due to increase in O2 consumption and decrease in blood supply caused by sympathomimetics that may lead to delay wound healing, tissue edema and necrosis. 1- Selective α1-blockers: Prazosin Therapeutic uses 1- Mild to moderate hypertension. 2- CHF as it decreases preload and afterload. 3- Decrease obstructive symptoms in benign prostatic hyperplasia (but tamsulosin is better as more selective on α 1a-receptor, causing less vasodilator side effects as hypotension and headache). (2) B- adrenergic blockers: - Non-selective B-blockers: - Propranolol, timolol - Selective B1-blockers: -Atenolol, esmolol (3) Non- selective α, B-adrenergic blockers. labetalol, and carvedilol Therapeutic uses 1) Cardiac: a) Mild to moderate hypertension. b) Chronic stable angina (not effective in acute attack, not used in variant angina) c) Cardiac arrhythmia 2) Endocrinal uses: a) Hyperthyroidism: b) Pheochromocytoma: 3) Neurological uses: a) Prophylactic in migraine. b) Essential tremors. c) Control of alcohol withdrawal manifestations. d) Control of acute panic symptoms e) Anxiety 4) Eye uses: Timolol can be used in treatment of glaucoma Side Effects 1- CHF, Severe bradycardia and heart block in susceptible patients. 2- On sudden withdrawal, there is exaggeration of symptoms due to receptors up regulation. 3- Sexual dysfunction and allergic reaction. 4- Side effects more with non-selective B-blockers, rarely with selective B1 -blockers: a) Cold extremities and increasing in the symptoms of peripheral vascular diseases b) Bronchoconstriction in asthmatics. c) Potentiate the hypoglycemic effect of insulin and mask symptoms of hypoglycemia. Implication of sympathetic drugs for Dentistry 1-Some drugs cause xerostomia as: -α2-agonists as clonidine and α-methyldopa -Adrenergic neuron blockers -α-antagonists -The long term use of these drugs may be associated with high incidence of oral candidiasis and dental caries 2-The use of B- blockers alter the composition of salivary protein that may adversely influence oral health 3-Patients using non-selective B-blockers may develop hypertensive crisis if vasoconstrictor drugs are used with local anesthetics 4-Patients using MAO-inhibitors should avoid the use of indirect sympathomimetics or any drug metabolized by the MAO to avoid hypertensive crisis. 5-Patients using antihypertensive drugs may develop syncope with sudden standing upright after being in a supine position in the dental chair.