Clinical Pharmacokinetics Flashcards
What is a barrier to drug distribution?
Any factor that influences how a drug is supplied to its site of action can be regarded as a barrier to distribution.
What does E-Evacuation mean?
E represents excretion and sometimes elimination.
What is the primary organ associated with drug metabolism?
The Liver.
Which are more easily excreted? Water soluble drugs or lipid soluble agents?
In general, water-soluble drugs are more easily excreted than lipid-soluble agents. Renal excretion is affected by renal function, which varies from birth into old age. Poor renal function requires that the doses of some drugs have to be adjusted to compensate for the body’s inability to excrete the agents.
Which route is affected by first-pass metabolism?
Oral. First-pass metabolism occurs when drugs are absorbed from the gastro-intestinal tract and pass through the liver before reaching the systemic blood supply. This can result in significant amounts of the drug being metabolised before it can be effective.
Which route can facilitate the fastest onset of action?
The intravenous route allows a drug to instantly enter the bloodstream and be quickly disturbed throughout the body. As such, it is the route we use when we need a drug to be effective quickly.
Which route avoids first-pass metabolism and can be easily self-administered by the patient?
Subcutaneous. While intravenous and intramuscular routes do bypass first-pass metabolism, they require specific training to administer and are rarely self-administered (an exception to this is the administration of adrenaline in instances of anaphylactic reactions). However, the subcutaneous route is easier for patients who can be taught to self-administer drugs that cannot be taken by the oral route (such as insulin or heparin).
Drugs administered by the inhaled route…?
Can make it difficult to regulate an exact dose.
What bypasses first-pass metabolism?
Rectal administration
What is Pharmocodynamics?
Pharmacodynamics examines the interaction between a drug and its site of action. This will include what type of receptor it binds to and what effects the binding will have. The relative benefit of different routes of administration for a given drug is considered part of its pharmacokinetics.
With regard to pharmacodynamics, what is a receptor?
A binding site that a chemical can bind to and elicit a response from
A G-protein linked second messenger system is …?
A mechanism in which receptor binding activates G-proteins, which in turn activates enzymes within a cell
What is the definition of a antagonist?
A substance that binds to a receptor and causes no response
What is the definition of a partial antagonist?
A substance that binds to a receptor and causes a smaller response than that produced by an endogenous signalling molecule.
What is a super agonist ?
A substance that binds to a receptor and causes a greater response than that produced by an endogenous signaling molecule.
