NEET MDS Lessons
Pharmacology
ANTIDEPRESSANTS
Monoamine uptake inhibitors
1. Tricyclic antidepressants (TCAs)
2. Selective serotonin reuptake inhibitors (SSRIs)
3. Serotonin-norepinephrine reuptake inhibitors(SNRIs)
4. Norepinephrine reuptake inhibitor
Monoamine oxidase inhibitors (MAOIs)
Monoamine receptor antagonists
NATURAL ANTICOAGULANTS:
1. PGI-2.
2. Antithrombin.
3. Protein-C.
4. TFPI.
5. Heparin.
6. Fibrinolytic system.
Calcium Channel Blocking Agents
• Act on contractile and conductive tissues of the heart and on vascular smooth muscles
• Prevent movement of extracellular calcium into the cell
– Coronary and peripheral arteries dilate
– Myocardial contractility decreases
– Depress conduction system
Therapeutic Actions
• Inhibit movement of calcium ions across the membranes of myocardial and arterial muscle cells. Altering the action potential and blocking muscle cell contraction
• Depress myocardial contractility
• Slow cardiac impulse formation in the conductive tissues
• Cause a fall in BP
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).
Classification
1. Natural Alkaloids of Opium
Phenanthrenes -> morphine, codeine, thebaine
Benzylisoquinolines -> papaverine, noscapine
2. Semi-synthetic Derivatives
diacetylmorphine (heroin) hydromorphone, oxymorphone hydrocodone, oxycodone
3. Synthetic Derivatives
phenylpiperidines pethidine, fentanyl, alfentanyl, sufentnyl
benzmorphans pentazocine, phenazocine, cyclazocine
propionanilides methadone
morphinans levorphanol
Osmotic diuretics
An osmotic diuretic is a type of diuretic that inhibits reabsorption of water and sodium. They are pharmacologically inert substances that are given intravenously. They increase the osmolarity of blood and renal filtrate.
Mechanism(s) of Action
1. Reduce tissue fluid (edema)
2. Reflex cardiovascular effect by osmotic retention of fluid within vascular space which increases blood volume (contraindicated with Congestive heart failure)
3. Diuretic effect
o Makes H2O reabsorption far more difficult for tubular segments insufficient Na & H2O capacity in distal segments
o Increased intramedullary blood flow (washout)
o Incomplete sodium recapture (asc. loop). this is indirect inhibition of Na reabsorption (Na stays in tubule because water stays)
o Net diuretic effect:
Tubular concentration of sodium decreases
Total amount of sodium lost amount increases
GFR unchanged or slightly increased
Toxicity
Circulatory overload, dilutional hyponatremia, Hyperkalemia, edema, skin necrosis
Agents
Mannitol
Treatment modifications to consider if there are concerns regarding vasoconstrictors
- Monitor blood pressure and heart rate preoperatively
- Minimize administration of epinephrine or levonordefrin
- Monitor blood pressure and heart rate 5 min after injection
- May re-administer epinephrine or levonordefrin if blood pressure and heart rate are stable
- Continue to monitor as required
- Consider limiting epinephrine to 0.04 mg, levonordefrin to 0.2 mg
- Avoid epinephrine 1:50,000
- Never use epinephrine-impregnated retraction cord