NEET MDS Lessons
Pharmacology
Classification
I) Esters
1. Formed from an aromatic acid and an amino alcohol.
2. Examples of ester type local anesthetics:
Procaine
Chloroprocaine
Tetracaine
Cocaine
Benzocaine- topical applications only
2) Amides
1. Formed from an aromatic amine and an amino acid.
2. Examples of amide type local anesthetics:
Articaine
Mepivacaine
Bupivacaine
Prilocaine
Etidocaine
Ropivacaine
Lidocaine
Ketorolac
Mechanism of action
primary action responsible for its anti-inflammatory/antipyretic/analgesic effects is inhibition of prostaglandin synthesis through inhibition of the enzyme cyclooxygenase (COX). Ketorolac is not a selective inhibitor of COX enzymes
Indications: short-term management of pain
Contraindications
hypersensitivity to ketorolac, and against patients with the complete or partial syndrome of nasal polyps, angioedema, bronchospastic reactivity or other allergic manifestations to aspirin or other non-steroidal anti-inflammatory drugs (due to possibility of severe anaphylaxis).
Methods of general anesthesia
CIRCLE SYSTEM
*HIGH-FLOW
FRESH GAS FLOW > 3 l/min.
*LOW-FLOW
FGF ok. 1l/min.
*MINIMAL-FLOW
FGF ok. 0,5 l/min.
Cough is a protective reflex which helps in expulsion of respiratory secretion or foreign particles which are irritant to respiratory
tract. Irritation to any part of respiratory tract starting from pharynx to lungs carried impulses by afferent fibres in vagus and
sympathetic nerve to the cough centre in the medulla oblongata. \
Cough may be dry (without sputum or unproductive) or productive (with sputum production).
Classification for drugs used in cough.
I. Pharyngeal demulcents
Certain lozenges, linctus and cough drops containing glycerine, liquorice and syrups.
II. Expectorants
Sodium and potassium citrate
Sodium and potassium acetate
Potassium iodide
Ammonium chloride & carbonate
Acetylcysteine
Bromhexine
Guaiphenesin
III. Antitussive
i. Opioids
Codeine (as linctus) Pholcodeine
ii. Non-opioids
Noscapine
Dextromethorphan
Pipazethate
iii. Antihistaminics
Chlorpheniramine
Diphenhydramine
Promethazine
Erdosteine is recently introduced mucolytic with unique protective functions for the respiratory tract. It is indicated in the treatment of acute and chronic airway diseases such as bronchitis, rhinitis, sinusitis, laryngopharyngitis and exacerbations of chronic bronchitis.
BradyKinin
An endogenous vasodilator occurring in blood vessel walls.
At least two distinct receptor types, B1 and B2, appear to exist for BradyKinin
Roles of bradykinin:
1) Mediator of inflammation and pain.
2) Regulation of microcirculation.
3) Their production is interrelated with clotting and fibrinolysin systems.
4) Responsible for circulatory change after birth.
5) Involved in shock and some immune reactions.
CARDIAC GLYCOSIDES
Cardiac glycosides (Digitalis)
Digoxin
Digitoxin
Sympathomimetics
Dobutamine
Dopamine
Vasodilators
α-blockers (prazosin)
Nitroprusside
ACE-inhibitors (captopril)
Pharmacology of Cardiac Glycosides
1. Positive inotropic effect (as a result of increase C.O., the symptoms of CHF subside).
2. Effects on other cardiac parameters
1) Excitability
2) Conduction Velocity; slightly increased in atria & ventricle/significantly
reduced in conducting tissue esp. A-V node and His-Purkinje System
3) Refractory Period; slightly ^ in atria & nodal tissue/slightly v in ventricles
4) Automaticity; can be greatly augmented - of particular concern in ventricle
3. Heart Rate
-Decrease due to 1) vagal stimulation and 2) in the situation of CHF, due to improved hemodynamics
4 Blood Pressure
-In CHF, not of much consequence. Changes are generally secondary to improved cardiac performance.
-In the absence of CHF, some evidence for a direct increase in PVR due to vasoconstriction.
5. Diuresis
-Due primarily to increase in renal blood flow as a consequence of positive inotropic effect (increase CO etc.) Possibly some slight direct diuretic effect.
Mechanism of Action of Cardiac Glycosides
Associated with an interaction with membrane-bound Na+-K+ ATPase (Na-K pump).
Clinical ramifications of an interaction of cardiac glycosides with the Na+ K pump.
I. Increase levels of Ca++, Increase therapeutic and toxic effects of cardiac glycosides
II. Decrease levels of K+ , Increase toxic effects of cardiac glycosides
Therapeutic Uses of Cardiac Glycosides
- CHF
- CHF accompanied by atrial fibrillation
- Supraventricular arrhythmias
Carbamazepine (Tegretol): most common; for generalized tonic-clonic and all partial seizures; especially active in temporal lobe epilepsies
Mechanism: ↓ reactivation of Na channels (↑ refractory period, blocks high frequency cell firing, ↓ seizure spread)
Side effects: induces hepatic microsomal enzymes (can enhance metabolism of other drugs)