NEET MDS Lessons
Pharmacology
Sufentanil
- A synthetic opioid related to fentanyl.
- About 7 times more potent than fentanyl.
- Has a slightly more rapid onset of action than fentanyl.
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.
Benzylpenicillin (penicillin G)
Benzylpenicillin, commonly known as penicillin G, is the gold standard penicillin. Penicillin G is typically given by a parenteral route of administration because it is unstable to the hydrochloric acid of the stomach.
Indications :
bacterial endocarditis, meningitis, aspiration pneumonia, lung abscess,community-acquired pneumonia, syphilis, septicaemia in children
Antiemetics
Antiemetic drugs are generally more effective in prophylaxis than treatment. Most antiemetic agents relieve nausea and vomiting by acting on the vomiting centre, dopamine receptors, chemoreceptors trigger zone (CTZ), cerebral cortex, vestibular apparatus, or a combination of these.
Drugs used in the treatment of nausea and vomiting belong to several different groups. These include:
1. Phenothiazines, such as chlorpromazine, act on CTZ and vomiting centre, block dopamine receptors, are effective in preventing or treating nausea and vomiting induced by drugs, radiation therapy, surgery and most other stimuli (e.g. pregnancy).
They are generally ineffective in motion sickness.
Droperidol had been used most often for sedation in endoscopy and surgery, usually in combination with opioids or benzodiazepines
2. Antihistamines such as promethazine and Dimenhyrinate are especially effective in prevention and treatment of motion.
3. Metoclopramide has both central and peripheral antiemetic effects. Centrally, it antagonizes the action of dopamine. Peripherally metoclopramide stimulates the release of acetylcholine, which in turn, increases the rate of gastric. It has similar indications to those of chlorpromazine.
4. Scopolamine, an anticholinergic drug, is very effective in reliving nausea & vomiting associated with motion sickness.
5. Ondansetron, a serotonin antagonist, is effective in controlling chemical-induced vomiting and nausea such those induced by anticancer drugs.
6. Benzodiazepines: The antiemetic potency of lorazepam and alprazolam is low. Their beneficial effects may be due to their sedative, anxiolytic, and amnesic properties
Eicosanoid compounds
Prostaglandines, Leukotriens and Thromboxanes.
They are produced in minute amounts by all cells except RBCs and they act locally at the same site of synthesis.
These agents have many physiological processes as mediators and modulators of inflammatory reactions.
Pramlintide -Amylin mimetics
Mechanism
synthetic analogue of human amylin that acts in conjunction with insulin
↓ release of glucagon
delays gastric emptying
Clinical use
type I and II DM
Cephalosporins
Produced semisynthetically by chemical attachment of side chains to 7-aminocephalosporanic acid. Same mode of action , same resistance mech.
But tend to be more resistant than penicillins to certain beta –lactamases .
GENERATION BASED ON :
-- BACTERIAL SUSCEPTIBILITY PATTERNS
-- RESISTANCE TO BETA –LACTAMASES
--NOT EFFECTIVE AGAINST -MRSA , L. MONOCYTOGENES , C. DIFFICLE , ENTEROCOCCI
First Generation
Parentral
- CEPHALOTHIN
- CEFAZOLIN
Oral
- CEPHALEXIN
- CEPHRADINE
- CEFADROXIL
Second Generation
Parentral
CEFUROXIME
CEFOXITIN
Oral
CEFACLOR
CEFUROXIME AXETIL
Third Generation
Parentral
CEFOTAXIME
CEFTIZOXIME
CEFTRIAXONE
CEFTAZIDIME
CEFOPERAZONE
Oral
CEFIXIME
CEFPODOXIME
CEFDINIR
CEFTIBUTEN
Fourth Generation
Parentral
CEFEPIME
CEFPIROME