NEET MDS Lessons
Pharmacology
Propofol -Intravenous Anesthetics
- A nonbarbiturate anesthetic
- It is very lipid-soluble, acts rapidly and has a short recovery time.
- It is associated with less nausea and vomiting than some of the other IV anesthetics.
- Propofol is very similar to thiopental in its effects on the cardiorespiratory system.
- It does not have any analgesic properties but lowers the dose of opioid needed when the two agents are used in combination.
- The most significant adverse cardiovascular effect associated with propofol administration is hypotension. It should be used with caution in patients with cardiac disease.
Oxyphenbutazone: one of the metabolites of phenylbutazone. Apazone. Similar to phenylbutazone, but less likely to cause agranulocytosis
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
Halothane (Fluothane) MAC 0.76%, Blood/gas solubility ratio 2.3
- Nonflammable.
- Any depth of anesthesia can be obtained in the absence of hypoxia.
- Halothane produces a marked hypotensive effect
- accompanies hypotension.
- Halothane “sensitizes” the ventricular conduction system in the heart to the action of catecholamines. However, ventricular arrhythmias are rare if
- respiratory acidosis, hypoxia and other causes of sympathetic stimulation are avoided.
- Respiration is depressed by all anesthetic concentrations.
- Halothane is metabolized to a significant extent and some of its metabolic produces have been shown to be hepatotoxic.
- Can produce a malignant hyperpyrexia due to an uncontrolled hypermetabolic reaction in skeletal muscle.
Halothane is generally used with nitrous oxide, an opiate and a neuromuscular blocking drug.
Buspirone
1. Short half-life (2–4 hours).
2. Relieves anxiety.
3. Does not act as an anticonvulsant.
4. Is not a good muscle relaxant.
5. Minimum abuse potential.
Lamotrigine (Lamictal): newer; broad spectrum (for most seizure types)
Mechanism: ↓ reactivation of Na channels (↑ refractory period, blocks high frequency cell firing)
Side effects: dizziness, ataxia, fatigue, nausea, no significant drug interactions
Sulfonylureas
1st generation
tolbutamide
chlorpropamide
2nd generation
glyburide
glimepiride
glipizide
Mechanism
glucose normally triggers insulin release from pancreatic β cells by increasing intracellular ATP
→ closes K+ channels → depolarization → ↑ Ca2+ influx → insulin release
sulfonylureas mimic action of glucose by closing K+ channels in pancreatic β cells
→ depolarization → ↑ Ca2+ influx → insulin release
its use results in
↓ glucagon release
↑ insulin sensitivity in muscle and liver
Clinical use
type II DM
stimulates release of endogenous insulin
cannot be used in type I DM due to complete lack of islet function
Toxicity
first generation
disulfiram-like effects
especially chlorpropamide
second generation
hypoglycemia
weight gain