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3. Old stuff 3.1.3. Pharmacology 3.1.3.1. Pharmacology principles 3.1.3.1.2. Pharmacodynamics 3.1.3.1.2.3. Dose-response relationship
3.1.3.1.2.3.1. Drug response and tolerance drug response and tolerance
[SH4:p5]Special terms
Hyperreactivity
- Hyperreactivity describes unusually low dose produce the expected pharmacological reponse
Hypersensitivity
- Hypersenstivity is usually used to describe allergic reactions
Hyporeactive
- Hyporeactive describes situation where an exceptionally large dose is required to produced the desired/expected pharamcologic effect
Tolerance
- Tolerance is when hyporeactivity is acquired from chronic exposure to a drug
Tachyphylaxis
- Tachyphylaxis is where tolerance develops within a few doses of a drug
- e.g. nitrate, suxamethonium, ephedrine
Idiosyncrasy
- ... where unusual effect of a drug occurs in a small percentage of population (regardless of the dose of drug administered)
Mechanism of tolerance
1. Development of cellular tolerance
aka neuronal adaptation
- Most important of all mechanisms
- Responsible for tolerance to:
* opoids
* barbituates
* alcohol
2. Enzyme induction
3. Depletion of neurotransmitter
- ... where there has been sustained stimulation
4. Formation of antibodies to the drug
- Immunity is involved