NEET MDS Lessons
Pharmacology
Ether (diethylether)
Ether (diethylether) MAC 2.0%, Blood/gas solubility ratio 15
- Ether is generally mixed with 3% ethanol to retard oxidation. Peroxides form on exposure to air and can enhance the danger of an explosion.
- Slow rate of induction and recovery due to its high blood/gas solubility ratio.
- Produces profound muscular relaxation.
- Both the rate and the minute volume of ventilation tend to be elevated during the inhalation of ether.
- Ether maintains good circulatory stability and does not sensitize the heart to the arrhythmogenic action of catecholamines.
- More than 90% of the absorbed ether can be recovered unchanged in the expired air. Metabolism is not extensive and the metabolites are not hepatotoxic.
- Ether is a versatile anesthetic of unexcelled safety, but it is flammable and irritating to breathe. Secretions can be blocked with anticholinergics.
DIURETICS
|
Specific Therapeutic Objective |
Clinical State(s) |
Drug(s) (Class) |
|
Draw fluid from tissue to vascular space reduce tissue edema |
Cerebral edema |
Mannitol (Osmotic) |
|
Decrease renal swelling |
Renal shutdown |
Glucose (Osmotic) |
|
Modest and/or sustained decrease in venous hydrostatic pressure |
Congestive heart failure |
Hydrochlorothiazide (thiazide) |
|
Aggressive and/or short-term decrease in venous hydrostatic pressure |
Congestive heart failure |
Furosemide (loop) |
|
Inhibit aldosterone action |
Hepatic cirrhosis |
triamterene (K+ sparing) |
|
Reduce potassium wasting 2o to other diuretic |
Hepatic cirrhosis |
triamterene (K+ sparing) |
|
Inhibit ADH action |
Inappropriate ADH secretion |
lithium (aquaretic) |
|
Increase calcium secretion |
Malignant hypercalcemia
|
Furosemide (loop) |
|
Reduce urine output |
Diabetes insidpidus |
Hydrochlorothiazide (thiazide) |
|
Urine alkalinization |
Various |
Carbonic anhydrase inhibitors |
Streptomycin
Streptomycin was the first of a class of drugs called aminoglycosides to be discovered, and was the first antibiotic remedy for tuberculosis. It is derived from the actinobacterium Streptomyces griseus.
Streptomycin cannot be given orally, but must be administered by regular intramuscular injection.
Anticonvulsants: include carbamazepine (use when lithium not tolerated; may not be as effective) .
valproic acid (use when lithium not tolerated; rapid onset)
Metabolism
Hepatic Drug-Metabolizing Enzymes: most drug metabolism in the liverperformed by the hepatic microsomal enzyme system.
Therapeutic Consequences of Drug Metabolism
- Accelerated Renal Drug Excretion: The most important consequence of drug metabolism is the promotion of renal drug excretion. Metabolism makes it possible for the kidney to excrete many drugs that it otherwise could not.
- Drug Inactivation
- Increased Therapeutic Action: Metabolism may increase the effectiveness of some drugs.
- Activation of Prodrugs: A prodrug is a compound that is inactive when administered and made active by conversion in the body.
- Increased or Decreased Toxicity
Factors that influence rate of metabolism:
- Age: Hepatic maturation doesn't occur until about a year old.
- Induction of Drug-Metabolizing Enzymes: Some drugs can cause the rate of metabolism to increase, leading to the need for an increased dosage. May also influence the rate of metabolism for other drugs taken at the same time, leading to a need for increased dosages of those drugs as well.
- First-Pass Effect: Hepatic inactivation of certain oral drugs. Avoided by parentaral administration of drugs that undergo rapid hepatic metabolism.
- Nutritional Status
- Competition between Drugs
Megltinides
nateglinide
repaglinide
Mechanism
binds to K+ channels on β-cells → postprandial insulin release
Clinical use
type 2 diabetes mellitus
may be used as monotherapy, or in combination with metformin
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.