Pharmacodynamics & Receptors

Tachyphylaxis

A rapid acute decrease in response typically due to agonist usage

Agonist binding to G protein coupled receptor

Alpha GTP complex becomes active. The alpha GTP complex activate cellular effectors

Alpha subunit

It must be bound to GTP to be active

Beta gamma complex

While it can have signaling roles the primary initiator of the main cascade is Alpha GTP complex

Alpha GDP complex

This is inactive resting state of G protein

Gamma subunits

Does not act alone; remains part of the beta-gamma dimer

Tachyphylaxis (Definition 2)

Rapid tolerance to a drug

Down Regulation

Reduction of cell receptors

Drug Resistence

Microbes and cancer cells evading a drugs mechanism

Full Agonist

They bind to the receptor 100% of their capacity

Competitive Antagonist

Binds the receptor but blocks the physiological response of an agonist

Inverse Agonist

Binds the receptor but induces the opposite physiological response of an agonist

Allosteric Antagonist

Binds to a diffrent site on the receptor altering its shape so the agonist cannot work

Special Populations, Prescribing & Therapeutics

Prescribing cascade

The risk is the increased likelihood of adverse drug effects and drug-drug interactions due to the addition of an unnecessary drug

Decreased Phisiological Reserve

Relates to aging but does not describe the act of prescribing new drugs for side effects

Beers Criteria

It lists dangerous drugs for elderly

FDA Pregnancy categories

List of pregnancy drugs

Paracetamol

Wide thearapatic range

Lithium

Narrow TI (used for bipolar easily toxic)

Digoxin (Therapeutic Index)

Extremely narrow (used for heart failure)

Gentamicin

Narrow (Needs monitoring of blood to prevent kidney ear damage.)

Phenytoin

Narrow (seizure drug)