Pharmacodynamics Study: Targets for Drug Action

Pharmacodynamics is the division of pharmacology that studies what the body does to the drug.

Most drugs are effective because they bind to specific target proteins like enzymes, carriers, and ion channels.

Cytotoxic drugs work by stimulating physiological functions.

Bulk laxatives exert their mechanism of action through chemical interactions.

Enzymes can be inhibited by both competitive and non-competitive inhibition.

Epinephrine acts on alpha receptors in the heart.

Competitive antagonism results in a curve that shifts to the left without a change in slope.

Non-competitive antagonism can be reversed by increasing the concentration of the agonist drug.

Tachyphylaxis refers to a gradual increase in responsiveness to a drug over time.

Irreversible antagonism is characterized by the drug binding to an allosteric site on the receptor.

Tolerance is a phenomenon that develops within minutes of drug administration.

Competitive antagonism involves drugs that exert an antagonistic effect without competing for receptor occupancy.

Partial agonists have low affinity and high intrinsic activity.

Antagonists bind to receptors and elicit tissue responses.

High affinity drugs bind well and remain long enough to activate receptors.

Antagonists have high affinity but no intrinsic activity.

Full agonists have low intrinsic activity and low affinity.

Potency refers to the intensity of the drug effect produced by a given amount or dose of the drug.

The process of down regulation of receptors occurs due to excessive exposure to antagonists.

Exhaustion of mediators can lead to an increase in essential immediate substances.

Increased metabolic degradation results in a progressive increase in plasma concentration of a drug.

Therapeutic Index (TI) is calculated as TD50 / ED50.

Nicotinic receptor is an example of a receptor linked to G-proteins.

The rate at which drugs act depends on the dose administered.

G-protein-coupled receptors mainly use cAMP and IP3 as their principal third messengers.

Adenylate cyclase catalyzes the conversion of cAMP to ATP.

IP3 is responsible for controlling the release of sodium ions from intracellular stores.

Kinase-linked receptors are mainly involved in events controlling cell death.

The Jak/Stat pathway is activated by many cytokines and controls the synthesis and release of many anti-inflammatory mediators.

The insulin receptor autophosphorylates in response to insulin.