NEET MDS Lessons
Pharmacology
Enflurane (Ethrane) MAC 1.68, Blood/gas solubility ratio 1.9
- Extremely stable chemically.
- Less potent and less soluble in blood than is halothane.
- Respiratory depression is similar to that seen with halothane.
- Cardiac output is not depressed as much as with halothane, and the heart is not sensitized to catecholamines to the same degree.
- Enflurane produces better muscle relaxation than does halothane.
- Metabolism of this agent is very low. Inorganic fluoride is a product of metabolism, but is not sufficient to cause renal problems.
- Enflurane differs from halothane and the other inhalational anesthetic agents by causing seizures at doses slightly higher than those that induce anesthesia.
- Nausea appears to occur somewhat more often following Enflurane than it does following halothane.
GENERAL ANESTHETICS
General anesthesia often involves more than one drug to get different, favourable effects.
Premedication is often used to:
1. Treat anxiety - Benzodiazapenes
2. Reduce pain - Opiod anaglesics such as morphine
3. Produce muscle paralysis -E.g. Tubocurare
4. Reduce secretions
Induction of anesthesia is often done via intravenous anesthetics, which are quick and easy to administer.
Maintenance of anesthesia involves inhalation agents.
Prototype Agents:
Volatile Anesthetics:
• Nitrous Oxide
• Ether
• Halothane
• Enflurane
• Isoflurane
Injectable Anesthetics:
• Thiopental
• Ketamine
• Etomidate
• Propofol
• Midazolam
Itraconazole:
The drug may be given orally or intravenously.
Diclofenac
Short half life (1‐2 hrs), high 1stpass metab., accumulates in synovial fluid after oral admn., reduce inflammation, such as in arthritis or acute injury
Mechanism of action
inhibition of prostaglandin synthesis by inhibition of cyclooxygenase (COX). There is some evidence that diclofenac inhibits the lipooxygenase pathways, thus reducing formation of the
leukotrienes (also pro-inflammatory autacoids). There is also speculation that diclofenac may inhibit phospholipase A2 as part of its mechanism of action. These additional actions may explain the high potency of diclofenac - it is the most potent NSAID on a molar basis.
Inhibition of COX also decreases prostaglandins in the epithelium of the stomach, making it more sensitive to corrosion by gastric acid. This is also the main side effect of diclofenac and other drugs that are not selective for the COX2-isoenzyme.
Sufentanil
- A synthetic opioid related to fentanyl.
- About 7 times more potent than fentanyl.
- Has a slightly more rapid onset of action than fentanyl.
BETA-LACTAM ANTIBIOTICS
β-lactam antibiotics are a broad class of antibiotics including penicillin derivatives, cephalosporins, monobactams, carbapenems and β-lactamase inhibitors; basically any antibiotic agent which contains a β-lactam nucleus in its molecular structure. They are the most widely used group of antibiotics available.
Mode of action All β-lactam antibiotics are bactericidal, and act by inhibiting the synthesis of the peptidoglycan layer of bacterial cell walls.β-lactam antibiotics were mainly active only against Gram-positive bacteria, the development of broad-spectrum β-lactam antibiotics active against various Gram-negative organisms has increased the usefulness of the β-lactam antibiotics.
Common β-lactam antibiotics
Penicillins
Narrow spectrum penicillins:
benzathine penicillin
benzylpenicillin (penicillin G)
phenoxymethylpenicillin (penicillin V)
procaine penicillin
Narrow spectrum penicillinase-resistant penicillins
methicillin
dicloxacillin
flucloxacillin
Moderate spectrum penicillins :
amoxicillin, ampicillin
Broad spectrum penicillins :
co-amoxiclav (amoxycillin+clavulanic acid)
Extended Spectrum Penicillins:
piperacillin
ticarcillin
azlocillin
carbenicillin
Lithium carbonate: 1st choice (controls mania in bipolar disorders); delay before onset of therapeutic benefit; no psychotropic effects in normal humans
i. Mechanism: blocks enzymes in inositol phosphate signaling pathway; no consistent effects of lithium on NE, 5-HT, and DA
ii. Side effects: severe CNS (ataxia, delirium, coma, convulsions) and CV (cardiac dysrhythmias)