NEET MDS Lessons
Pharmacology
Isoflurane (Forane) MAC 1.3%, Blood/gas solubility ratio 1.4
- Better muscle relaxation than with the other halogenated anesthetic agents.
- Isoflurane markedly potentiates the action of the neuromuscular blocking agents.
- Produces rapid onset and recovery of anesthesia.
- Does not sensitize the heart to catecholamines.
- Produces respiratory depression, but produces less cardiovascular depression
- than does halothane.
- It has an extremely low degree of metabolism and is apparently relatively
- nontoxic.
Selective serotonin reuptake inhibitors (SSRIs)
e.g. fluoxetine, paroxetine, citalopram, and sertraline
- Most commonly used antidepressant category
- Less likely to cause anticholinergic side effects
- Relatively safest antidepressant group in overdose
- Selectively inhibits reuptake of serotonin(5-HT)
Mode of Action;
- Well absorbed when given orally
- Plasma half-lives of 18-24 h allowing once daily dosagedaily dosage
- Metabolised through CYP450 system and most SSRIs inhibit some CYP isoforms
- Therapeutic effect is delayed for 2-4 weeks
ADVERSE DRUG REACTIONS
- Insomnia, increased anxiety, irritability
- Decreased libido
- Erectile dysfunction, anorgasmia, and ejaculatory delay
- Bleeding disorders
- Withdrawal syndrome
Propoxyphene
- A methadone analog.Used orally to relieve mild to moderate pain.
- A typical opiate, it does not possess anti-inflammatory or antipyretic actions, but has little or no antitussive activity.
- Cannot be used parenterally because of irritant properties.
- Has a low addiction potential primarily due to its lack of potency as an opiate.
- The most common adverse side effects are:• dizziness, drowsiness, and nausea and vomiting. • these effects are more prominent in ambulatory patients.
- Withdrawal symptoms have occurred in both adults and in neonates following use of the drug by the mother during pregnancy.
- CNS depression is additive with other CNS depressants.
Ketoprofen
It acts by inhibiting the body's production of prostaglandin.
Hydromorphone
- About 8-10 times more potent than morphine when given intravenously.
- Slightly shorter duration of action.
- More soluble than morphine, thus higher concentrations may be injected if necessary.
- Better oral/parenteral absorption ratio than morphine, but not as good as codeine or oxycodone.
- It is used for the treatment of moderate to severe pain
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.
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.