Bioavailability Tutorial Flashcards
Define excipient
Other material added to a drug before prescription
Define formulation
Process in which different chemical substances are combined to produce a final medicinal product
Define bioequivalence
Evidence the new “generic” product behaves sufficiently similar to the original to be substituted for it without causing clinical problems
Give an advantage and disadvantage of oral admission
Permits self medication
Undergo extensive first pass metabolism
Give an advantage and disadvantage of IV admission
Rapid onset
Trained personal required
Give an advantage and disadvantage of inhalational admission
Huge surface area of alveolar membranes for absorbtion
Possible localised effect in lung
Give an advantage and disadvantage of IM admission
High blood flow, increased in exercise, enables depot therapy
Possible infection + nerve damage
Give an advantage and disadvantage of SC admission
Local administration, dissemination can be minimised for local effect
Possible pain
Give an advantage and disadvantage of percutaneous admission
Local application + action
Local irritation + skin reactions
Give 3 reasons why excipients are added to a drug formulation
To aid manufacture of the medicine
To improve chemical + biological stability
Increase acceptability to the patient by improving flavour, fragrance or appearance
How can the physiochemical characteristics, GI pH, transportation, gastric motility, particle size and GI interaction effect bioavailability?
Ratio of ionised: unionised effects bioavailability + movement through the body
pH effects ionisation state
Active transport requires energy, thus if lacking ATP, less drug will be bioavailable
Increased gut motility increases absorption
Smaller particles are absorbed more easily
Gut contents may interact with the drug making it inactive/ competing for its target site
What is the therapeutic window?
Range of doses between minimum effective concentrations to the minimum toxic concentration
What is the therapeutic index?
Comparison of amount of a therapeutic agent that causes therapeutic effect to the amount that causes toxicity.
How can good bioavailability be achieved for drugs that undergo extensive first-pass metabolism?
Parenteral administration e.g. IV
Under what circumstances could a drug, which undergoes 100% first pass metabolism, be therapeutically useful?
For a pro-drug where metabolism is required to liberate the active form of the drug