Drugs, Absorption and Distribution Flashcards
What defines drug absorption?
Transfer of drug from site of administration to the systemic circulation.
Define bioavailibilty
The fraction of the dose of the drug that reaches systemic circulation.
What factors determine the rate of absorption?
Blood flow, Surface area, Ionization state and lipophilicity.
What are the advantages and disadvantages of Oral adminisitration?
Adv: safe, convenient, economical, controlled rate of release.
Disadv: GI irritation, First pass effect, slow onset, possible destruction by enzymes.
Discuss the First Pass Effect
Loss of drug by metabolism in the GI mucosa and liver before the drug reaches the systemic circulation.
What are the advantages and disadvantages of Sublingual administration?
Adv: Rapid absorption, Eliminates first pass effect
Disadv: Limited to small doses with high potency, Can’t be given if irritating or bad taste.
What are the advantages and disadvantages of Rectal administration?
Adv: can be used in unconscious or vomiting patients, Less GI distress, No first pass effect
Disadv: Inconvenient, lack of adherence by patient
What are the advantages and disadvantages of IV administration?
Adv: Rapid action, complete dose in blood, controllable rate of administration.
Disadv: Painful, must be water soluble, dose is not retrievable once given.
What are the advantages and disadvantages of Subcutaneous administration?
Adv: Can control rate of absorption, rapid rate of absorption.
Disadv: Irritating drugs can’t be used.
What are the advantages and disadvantages of intramuscular administration?
Adv: Rapid absorption
Disadv: irritation, may hit blood vessel
What are the advantages and disadvantages of inhalation?
Adv: Rapi absorption and onset.
Disadv: Must use aerosol, hard to control size of dose.
What are the advantages and disadvantages of intraperitoneal administration?
Adv: Rapid absorption
Disadv: possibility of infection, first pass effect
What are the advantages and disadvantages of Intrathecal administration?
Adv: Entry into CSF
Disadv: Difficult, danger to nerves and leakage of CSF.
What are the advantages and disadvantages of topical administration?
Adv: local effect, controlled release
Disadv: Must be non-irritating, possibility of absorption into blood if damaged membranes.
