Drug action usually occurs in three phases: Pharmaceutical phase. Pharmacokinetic phase. Pharmacodynamic phase.
What are the types of drug action?
Based on drug action on receptors, there are 2 different types of drugs: Agonists – they stimulate and activate the receptors.
Intrinsic Activity which defines:
- Agonists as having Intrinsic Activity = 1.
- Antagonists as having Intrinsic Activity = 0.
- and, Partial Agonist as having Intrinsic Activity between 0 and 1.
What are the phases of drug effects?
Pharmacokinetic Phase. Pharmacokinetics is the process of drug movement to achieve drug action. The four processes are absorption, distribution, metabolism (or biotransformation), and excretion (or elimination). The nurse applies knowledge of pharmacokinetics when assessing the patient for possible adverse drug effects
What are the 4 categories of drug actions?
There are four types of ligand that act by binding to a cell surface receptor, agonists, antagonists, partial agonists, and inverse agonists (Figure 1). Ligand s that bind to a receptor and produce an appropriate response are called agonists.
What are the basic principle of drug actions?
Principles of drug action encompass three major topic areas: drug administration, pharmacokinetics, and pharmacodynamics.
What is the meaning of drug action?
The function of a drug in various body systems. Local: When the drug is applied locally or directly to a tissue or organ, it may combine with the cell’s membrane or penetrate the cell.
What are the 4 stages of pharmacodynamics?
Think of pharmacokinetics as a drug’s journey through the body, during which it passes through four different phases: absorption, distribution, metabolism, and excretion (ADME).
What is the pharmacodynamic phase?
This phase describes the mechanisms of drug action by which a drug molecule causes its effect on the body.
What is the pharmacokinetic phase?
This phase describes the time course and disposition of a drug in the body, based on its absorption, distribution, metabolism and elimination.
What is pharmacodynamics of a drug?
Pharmacodynamics describes the intensity of a drug effect in relation to its concentration in a body fluid, usually at the site of drug action. It can be simplified to ‘what the drug does to the body’.
What factors influence drug action?
A drug’s action is affected by the quantity of drug that reaches the receptor and the degree of attraction (affinity) between it and its receptor on the cell’s surface. Once bound to their receptor, drugs vary in their ability to produce an effect (intrinsic activity).
What are the five mechanisms of drug action?
The mechanisms of action include inhibition of bacterial protein synthesis, inhibition of cell wall synthesis, inhibition of enzymatic activity, alteration of cell membrane permeability, and blockade of specific biochemical pathways.
What are the principles of pharmacodynamics?
Pharmacodynamic mechanisms regulate the effects of drugs on the human body. As noted earlier, drug-receptor binding results in multiple, complex chemical interactions. The site on the receptor at which a drug binds is called its binding site.
What is drug receptor?
7.2 Drug receptors. Receptor is a macromolecule in the membrane or inside the cell that specifically (chemically) bind a ligand (drug). The binding of a drug to receptor depends on types of chemical bounds that can be established between drug and receptor.
What is the difference between drug action and drug effect?
It is important to distinguish between actions of drugs and their effects. Actions of drugs are the biochemical physiological mechanisms by which the chemical produces a response in living organisms. The effect is the observable consequence of a drug action.
What is systemic drug action?
Systemic drug therapy involves treatment that affects the body as a whole or that acts specifically on systems that involve the entire body, such as the cardiovascular, respiratory, gastrointestinal, or nervous systems. Mental disorders also are treated systemically.
What are the three most common drug forms?
Common dosage forms include tablets, capsules, creams, ointments, aerosols and patches. Each dosage form may also have a number of specialized forms such as extended-release, buccal, dispersible and chewable tablets.
What is duration of action of a drug?
The duration of action of a drug is known as its half life. This is the period of time required for the concentration or amount of drug in the body to be reduced by one-half. We usually consider the half life of a drug in relation to the amount of the drug in plasma.
What is peak drug action?
Peak : the peak of medication refers to the maximum concentration of medication in the body, and the patient shows evidence of greatest therapeutic effect. Duration : the duration of medication refers to the length of time the medication produces its desired therapeutic effect.
What are the six classification of drugs?
The 6 Classifications of Drugs. When considering only their chemical makeup, there are six main classifications of drugs: alcohol, opioids, benzodiazepines, cannabinoids, barbiturates, and hallucinogens.
What is t1 2 in pharmacology?
Half-life (t1/2) refers to the time required for plasma concentration of a drug to decrease by 50%. t1/2 is dependent on the rate constant (k), which is related to Vd & clearance (CL).