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Pharmacodynamics

Drug Effects on the Body: – Drugs induce or inhibit physiological processes in animals. – Drugs inhibit vital processes of parasites and microorganisms. – Antacids […]

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Drug Effects on the Body:
– Drugs induce or inhibit physiological processes in animals.
– Drugs inhibit vital processes of parasites and microorganisms.
– Antacids and chelating agents chemically combine in the body.
– Enzyme-substrate binding alters production or metabolism of chemicals.
– Drugs act as ligands binding to receptors for cellular effects.

Undesirable Effects:
– Increased probability of cell mutation.
– Assorted actions that may be deleterious.
– Interactions can be additive, multiplicative, or metabolic.
– Induced physiological damage or abnormal conditions.
– Adverse effects may vary based on genetic factors.

Therapeutic Window and Dosage:
– Range between effective dose and adverse effects.
– Medications with small therapeutic windows require careful administration.
– Monitoring blood concentration may be necessary.
– Helps determine safe and effective dosage.
– Important for balancing benefits and risks of medication.

Duration of Drug Action:
– Length of time a drug remains effective.
– Influenced by plasma half-life and target compartment equilibration.
– Off rate from biological target affects duration.
– Important consideration for dosing frequency.
– Factors affecting duration can vary among drugs.

Receptor Binding and Multicellular Pharmacodynamics:
– Ligand-receptor binding follows the law of mass action.
– Equilibrium dissociation constant defines binding affinity.
– Fraction of bound receptors influences drug effect.
– Occupancy of receptors relates to pharmacological response.
– Multicellular Pharmacodynamics involves studying static and dynamic properties of drugs in a multicellular system.

Pharmacodynamics (Wikipedia)

Pharmacodynamics (PD) is the study of the biochemical and physiologic effects of drugs (especially pharmaceutical drugs). The effects can include those manifested within animals (including humans), microorganisms, or combinations of organisms (for example, infection).

Topics of pharmacodynamics

Pharmacodynamics and pharmacokinetics are the main branches of pharmacology, being itself a topic of biology interested in the study of the interactions of both endogenous and exogenous chemical substances with living organisms.

In particular, pharmacodynamics is the study of how a drug affects an organism, whereas pharmacokinetics is the study of how the organism affects the drug. Both together influence dosing, benefit, and adverse effects. Pharmacodynamics is sometimes abbreviated as PD and pharmacokinetics as PK, especially in combined reference (for example, when speaking of PK/PD models).

Pharmacodynamics places particular emphasis on dose–response relationships, that is, the relationships between drug concentration and effect. One dominant example is drug-receptor interactions as modeled by

where L, R, and LR represent ligand (drug), receptor, and ligand-receptor complex concentrations, respectively. This equation represents a simplified model of reaction dynamics that can be studied mathematically through tools such as free energy maps.

IUPAC definition

Pharmacodynamics: Study of pharmacological actions on living systems, including the reactions with and binding to cell constituents, and the biochemical and physiological consequences of these actions.

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