NEET MDS Lessons
Pharmacology
Properties of inhalation anesthetics
The lower the solubility, the faster the onset and the faster the recoverability.
All general anesthetics:
1. inhibit the brain from responding to sensory stimulation.
2. block the sensory impulses from being recorded in memory.
3. prevent the sensory impulses from evoking “affect”.
Most general anesthetic agents act in part by interacting with the neuronal membranes to affect ion channels and membrane excitability.
· If the concentration given is too low:
1. Movement may occur
2. Reflex activity present (laryngeal spasm)
3. Hypertension
4. Awareness
Premedication of analgesic drugs and muscle relaxants are designed to minimise these effects
· If the concentration given is too high:
1. Myocardial depression
2. Respiratory depression
3. Delayed recovery
EPHEDRINE
It act indirectly and directly on α and β receptors. It increases blood pressure both by peripheral vasoconstriction and by increasing the cardiac output. Ephedrine also relaxes the bronchial smooth muscles.
Ephedrine stimulates CNS and produces restlessness, insomnia, anxiety and tremors.
Ephedrine produces mydriasis on local as well as systemic administration.
Ephedrine is useful for the treatment of chronic and moderate type of bronchial asthma, used as nasal decongestant and as a mydriatic without cycloplegia. It is also useful in preventing ventricular asystole in Stokes Adams syndrome.