3. Old stuff
          3.1. Old pharm stuff (pre 2009)
              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