Pharmacokinetics 1 Flashcards
What is pharmacokinetics? Why is it important?
What the body does to the drug. It is important as is will vary hugely in patients. It can identify drug interaction, predict the influence of diseases of drugs.
What does (L)ADME stand for? and what is it?
Liberation, Absorption, Distribution, Metabolism and Excretion. It is the 4/5 steps of pharmacokinetics
What are the advantages and disadvantages of oral route?
A - Convenient and safe.
D - First-pass effect, many variables and barriers
What are the advantages and disadvantages of sublingual route?
A - No first pass effect.
D - inconvenient, small dose limit and taste.
What are the advantages and disadvantages of Inhalation route?
A - Fast, rapid delivery to blood.
D - Requires special properties of drug
What are the advantages and disadvantages of topical route?
A - convenient, localised.
D - only localised
What are the advantages and disadvantages of transdermal route?
A - Prolonged release.
D - The skin is a very effective barrier
What are the advantages and disadvantages of intramuscular route?
A - rapid for aqueous, slow for oil.
D - painful and requires a trained professional.
What are the advantages and disadvantages of intravenous route?
A - direct, total dose and rapid.
D - Requires professional, injection risk and rapid response (Risk of anaphalxis)
What is bioavailabilty?
It is the fraction of unchanged drug that reaches the systemic circulation. IV bioavailability = 100% but oral can vary.
What are the four ways small molecules can cross cell membranes?
- Diffusing directly through lipid.
- Diffusing through aqueous pores.
- Transmembrane carrier protein.
- Pinocytosis (endocytosis of small molecules)
Features of hydophilic and lipophilic drugs
Hydrophilic - soluble in aqeuous, polar media.
Lipophilic - Soluble in fats and non-polar solutions so can pass through membranes
The ratio of ionised to unionised drugs depends on what? What pH are weak acids/bases less likely to become ionised in?
The pH.
- Weak acis are less likely to become ionised in acidic environments. A weak base is more likely to become ionised in an acid environment. (ionised drugs cannot cross membranes)
What are the main properties that affect drug absorption?
Lipophilicity and ionisation
What factors affect distribution?
Degree of drug ionisation, lipid solubility, pH of compartments, cardiac output and blood flow (low BF then less drug travailing to tissue), capillary permability and plasma binding protein.
