NEET MDS Lessons
Pharmacology
NSAIDs: Classification by Plasma Elimination Half Lives
Short Half Life (< 6 hours):
more rapid effect and clearance
• Aspirin (0.25-0.33 hrs),
• Diclofenac (1.1 ± 0.2 hrs)
• Ketoprofen (1.8± 0.4 hrs),
• Ibuprofen (2.1 ± 0.3 hrs)
• Indomethacin (4.6 ± 0.7 hrs)
Long Half Life (> 10 hours):
slower onset of effect and slower clearance
• Naproxen (14 ± 2 hrs)
• Sulindac (14 ± 8 hrs),
• Piroxicam (57 ± 22 hrs)
NATURAL ANTICOAGULANTS:
1. PGI-2.
2. Antithrombin.
3. Protein-C.
4. TFPI.
5. Heparin.
6. Fibrinolytic system.
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.
ANTIBIOTICS
Chemotherapy: Drugs which inhibit or kill the infecting organism and have no/minimum effect on the recipient.
Antibiotic these are substances produced by microorganisms which suppress the growth of or kill other micro-organisms at very low concentrations.
Anti-microbial Agents: synthetic as well as naturally obtained drugs that attenuate micro-organism.
SYNTHETIC ORGANIC ANTIMICROBIAL DRUGS
Sulfonamides
Trimethoprim-sulfamethoxazole
Quinolones – Ciprofloxacin
ANTIBIOTICS THAT ACT ON THE BACTERIAL CELL WALL
Penicillins
Cephalosporins
Vancomycin
INHIBITORS OF BACTERIAL PROTEIN SYNTHESIS
Aminoglycosides - Gentamicin
Antitubercular Drugs: Isoniazid & Rifampin
Tetracyclines
Chloramphenicol
Macrolides – Erythromycin, Azithromycin
Clindamycin
Mupirocin
Linezolid
ANTIFUNGAL DRUGS
Polyene Antibiotics (Amphotericin B, Nystatin and Candicidin)
Imidazole and Triazole Antifungal Drugs
Flucytosine
Griseofulvin
ANTIPROTOZOAL DRUGS
Antimalarial Drugs – Quinine, Chloroquine, Primaquine
Other Antiprotozoal Drugs – Metronidazole, Diloxanide, Iodoquinol
ANTIHELMINTHIC DRUGS
Praziquantel
Mebendazole
Ivermectin
ANTIVIRAL DRUGS
Acyclovir
Ribavirin
Dideoxynucleosides
Protease inhibitors
Benzylpenicillin (penicillin G)
Benzylpenicillin, commonly known as penicillin G, is the gold standard penicillin. Penicillin G is typically given by a parenteral route of administration because it is unstable to the hydrochloric acid of the stomach.
Indications :
bacterial endocarditis, meningitis, aspiration pneumonia, lung abscess,community-acquired pneumonia, syphilis, septicaemia in children
Classification Based on
a. Chemical structure
I. Sulphonamidcs.and others - c.g.. sulphadiazine. etc.
2. Beta-lactum ring - e.g.. penicillin
3. Tetracycline - e.g.. Oxytetracycline,.doxycycline.etc.
b. Mechanism of action
1. Inhibits cell-wall synthesis - penicillin. cephalosporin..cycloserine. etc.
2. Cause leakage from cell-membrane – polypeptides (polymyxin, Bacitracin), polyenes (Nystatin)
3. Inhibit protein synthesis - tetracyclines. chloramphenicols. erythromycin.
4. Cause mis-reading of mRNA code - aminoglycosides
5. Interfere with DNA function - refampicin.. metronidazole
6. Interfere with intermediary metabolism - sulphonamides. ethambutole
c. Type of organism against which it is primarily activate
I. Antibacterial - penicillin.
2. Antifungal - nystatin.
d. Spectrum of activity
1. Broad spectrum - tetracylines .
2. Narrow spectrum - penicillin G (penG). streptomycin.erythromycin
e. Type of action
I. Bacteriostatic - sulphonamides, erythromycin.tertracyclines
2. Bacteriocidal - penicillin. aminoglycoside
f. Source
I. Fungi - penicillin. cephalosporins
2. Bacteria - Polymyxin B
Sympatholytics (Antiadrenergic Agents)
PHENOXYBENZAMINE
It is a potent alpha-adrenergic blocking agent
It effectively prevents the responses mediated by alpha receptors and diastolic blood pressure tends to decrease.
It interferes with the reflex adjustment of blood pressure and produces postural hypotension.
It increases the cardiac output and decreases the total peripheral resistance.
It is used in the management of pheochromocytoma and also to treat peripheral vasospastic conditions e.g. Raynaud’s disease and shock syndrome.
Phentolamine, another alpha blocker is exclusively used for the diagnosis of pheochromocytoma and for the prevention of abrupt rise in blood pressure during surgical removal of adrenal medulla tumors.
ERGOT ALKALOIDS
Ergotamine is an important alkaloid that possesses both vasoconstrictor and alpha-receptor blocking activity. Both ergotamine and dihydroergotamine are used in the treatment of migraine.
METHYSERGIDE
It is a 5-hydroxytryptamine antagonist ). It is effective in preventing an attack of migraine.
SUMATRIPTAN
It is a potent selective 5-HT 1D receptor agonist used in the treatment of migraine.
PRAZOSIN
It is an piperazinyl quinazoline effective in the management of hypertension. It is highly selective for α1 receptors. It also reduces the venous return and cardiac output. It is used in essential hypertension, benign prostatic hypertrophy and in Raynaud’s syndrome.
Prazosin lowers blood pressure in human beings by relaxing both veins and resistance vessels but it dilates arterioles more than veins.
TERAZOSIN
It is similar to prazosin but has higher bioavailability and longer plasma t½
DOXAZOSIN
It is another potent and selective α1 adrenoceptor antagonist and quinazoline derivative.
It’s antihypertensive effect is produced by a reduction in smooth muscle tone of peripheral vascular beds.
TAMSULOSIN
It is uroselective α1A blocker and has been found effective in improving BPH symptoms.
Other drugs used for erectile dysfunction
Sildenafil: It is orally active selective inhibitor of phosphodiesterase type 5 useful in treatment of erectile dysfunction.