NEET MDS Lessons
Pharmacology
Ketamine
- Causes a dissociative anesthesia.
- Is similar to but less potent than phencyclidine.
- Induces amnesia, analgesia, catalepsy and anesthesia, but does not induce convulsions.
- The principal disadvantage of ketamine is its adverse psychic effects during emergence from anesthesia. These include: hallucinations, changes in mood and body image.
- During anesthesia, many of the protective reflexes are maintained, such as laryngeal, pharyngeal, eyelid and corneal reflexes.
- Muscle relaxation is poor.
- It is not indicated for intracranial operations because it increases cerebrospinal fluid pressure.
- Respiration is well maintained.
- Arterial blood pressure, cardiac output, and heart rate are all elevated.
Azithromycin
Azithromycin is the first macrolide antibiotic belonging to the azalide group. Azithromycin is derived from erythromycin by adding a nitrogen atom into the lactone ring of erythromycin A, thus making lactone ring 15-membered.
Azithromycin has similar antimicrobial spectrum as erythromycin, but is more effective against certain gram-negative bacteria, particularly Hemophilus influenzae.
azithromycin is acid-stable and can therefore be taken orally without being protected from gastric acids.
Main elimination route is through excretion in to the biliary fluid, and some can also be eliminated through urinary excretion
Loop (High Ceiling) Diuretics
Loop diuretics are diuretics that act at the ascending limb of the loop of Henle in the kidney. They are primarily used in medicine to treat hypertension and edema often due to congestive heart failure or renal insufficiency. While thiazide diuretics are more effective in patients with normal kidney function, loop diuretics are more effective in patients with impaired kidney function.
Agent: Furosemide
Mechanism(s) of Action
1. Diuretic effect is produced by inhibit of active 1 Na+, 1 K+, 2 Cl- co-transport (ascending limb - Loop of Henle).
o This produces potent diuresis as this is a relatively important Na re-absorption site.
2. Potassium wasting effect
a. Blood volume reduction leads to increased production of aldosterone
b. Increased distal Na load secondary to diuretic effect
c. a + b = increase Na (to blood) for K (to urine) exchange which produces indirect K wasting (same as thiazides but more likely)
3. Increased calcium clearance/decreased plasma calcium
o secondary to passive decreases in loop Ca++ reabsorption.
o This is linked to inhibition of Cl- reabsorption.
o This is an important clinical effect in patients with ABNORMAL High Ca++
Helicobacter Pylori Agents
Antimicrobial
• Amoxicillin,
• Clarithromycin,
• Metronidozole
• Tetracycline
Antisecreteory agents accelerates symptom relief and yield healing (omeprozole)
Bismuth subsalicylate
Therapy For H. Pylori
Original
• Tetracycline
• Metronidazole (Flagyl)
• Bismuth subsalicylate
• Given for 14 days
• >90% effective in eradicating microorganisms
New triple therapy
• Amoxicillin
• Clarithromycin
• Omeprazole (Prilosec)
• Given for 7 days
• >90% effective in eradicating microorganisms
Dual Therapy
Amoxicillin or clarithromycin
Omeprazole
Given for 14 days
60-80% effective in eradication of H. Pylori
Class IV Calcium Channel Blockers
• Block the movement of calcium into conductile and contractile myocardial cells
• Treatment: treatment of supraventricular tachycardia
– Diltiazem
– Verapamil
Adverse Effects
• Adverse effects associated with vasodilation of blood vessels throughout the body.
• CNS – dizziness, weakness, fatigue, depression and headache,
• GI upset, nausea, and vomiting.
• Hypotension CHF, shock arrhythmias, and edema
Phenobarbital (Luminal): for generalized tonic-clonic and partial seizures (not used for absence seizures)
Mechanism: enhances GABA inhibition (↑ open time of Cl channels in presence of GABA)
Side effects: sedation, ataxia, cognitive impairment, induction of hepatic microsomal enzymes
Uses of NSAIDs
NSAIDs are usually indicated for the treatment of acute or chronic conditions where pain and inflammation are present. Research continues into their potential for prevention of colorectal cancer, and treatment of other conditions, such as cancer and cardiovascular disease.
NSAIDs are generally indicated for the symptomatic relief of the following conditions.
rheumatoid arthritis, osteoarthritis, inflammatory arthropathies (e.g. ankylosing spondylitis, psoriatic arthritis, Reiter's syndrome), acute gout, dysmenorrhoea, metastatic bone pain ,headache and migraine, postoperative pain, mild-to-moderate pain due to inflammation and tissue injury, pyrexia, renal colic
Aspirin, the only NSAID able to irreversibly inhibit COX-1, is also indicated for inhibition of platelet aggregation; an indication useful in the management of arterial thrombosis and prevention of adverse cardiovascular events.