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17 Cards in this Set

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Pharmacodynamics

Affect of the drug on the body

Pharmacokinetics

Affect of the body on the drug

Indication/Contra-indication

Indication = condition where drug is helpful


Contraindication = condition in which drug not safe

Antagonist, Agonist

Agonist - stimulates recepttor action


Antagonist - blocks receptor action



Reversible vs Irreversible drugs

Reversible - dissociates from receptor leaving receptor still functional


Irreversible - drug does not dissociate, bound drug and receptor internalized and broken down, not able to be used again until new drug synthesized

Use dependant drugs

Only exert effects on activated receptors.

Drug half life

time taken for a 50% decrease in the drug concentration of the plasma. determined by Vd and clearance

Explain solubility of ionised vs unionised drugs


Explain effects of pH on acidic/basic drugs

Ionized - water soluble


Unionized - lipid soluble


Acidic - ionized in basic enviro/unionized in acidic


Basic - ionized in acidic enviro/unionized in basic




So you want a basic drug in a basic enviro/acidic drug in acidic enviro for movement across membranes



Ligand-gated ion channels

Time – milliseconds


Ligand (drug) binds to ion channel -> conformational change in structure -> opens channel -> ions pass through channel tointerior/exterior of cell -> hyperpolarization/depolarization

G protein coupled receptors

Time – seconds. V. common. Ligand binds tomembrane bound receptor. Part of receptor inside cell bound to G protein (αβγ)with GDP attached to α subunit. Ligand binds receptor site -> G protein changesconfirmation, GTP replaces GDP on α subunit. activated α subunit seperates fromβγ subunits -> α subunitactivates target. If 2 targets – βγ subunits activate other target. cAMP may act as secondary messenger to signal furtherintracellular events.

Kinase-linked receptors

Time – hours. Membrane receptors respond mainly to protein mediators eg. Cytokines Ligand binds receptor -> receptors undergo dimerization (2 receptorscome together – coupling). -> Phosphorylation inside cell – addition of phosphategroups to end of receptors inside cell -> intracellular effects due tophosphorylation.

Intracellular/Nuclear Receptors

Time – hours (involves protein synthesis). Receptors that regulate gene transmission -> up/down regulation of protein synthesis


Ligand diffuses through membrane à cytoplasm. Ligand binds -> inactivated receptor (eg. Transcriptonfactor). Ligand + receptor migrate -> nucleus and are ACTIVATED.


Complex ->transcription of DNA à protein synthesis

Volume of distribution

Volume ofdistribution: volume of fluid required to contain the total amount of drug inthe body at the same concentration as is present in the plasma.


Drugs with Vdsimilar to plasma conc – most of drug remains in plasma. High Vd = low plasmaconc. -> slower elimination.


Vd = dose/plasmaconcentration.


Half life directlyproportional to Vd – Vd determines elimination rate, which determines halflife.

2 phases of metabolism

1. Oxidation, reduction, hydrolysis or hydration by enzyme eg. cytochrome p450


2. Conjugation– synthesis of bond between drug and metabolite (exogenous substrate) -> polar molecule that can move through waterto be excreted, and is less biologically active.

Loading dose

High initial dose that gets plasma concentrationto therapeutic range. Dose then tapered in order to maintain plasmaconcentration in therapeutic range.

Steady State

level we aim to keep plasma conc. at for greatertherapeutic effects, but decreased side effects. generally takes 4-5 half lives. Drugs with high half life may require loading dose.

Clearance

sum of metabolism andelimination. Relates plasma conc. of drug to eliminationrate – efficiency of drug elimination from body. High clearance -> low half life. High plasma conc -> fast elimination rate.