Bb

• Pharmacokinetics is the study of the absorption, distribution, metabolism and excretion of a drug.
• Pharmacodynamics is the study of how drugs affect the body.
• Absorption is the process by which a drug enters the body.
• Distribution is the process by which a drug moves within the body.
• Metabolism is the process by which a drug is broken down within the body.
• Excretion is the process by which a drug leaves the body.
• The principal routes of drug administration are oral, parenteral, inhalation, and topical.
• Agonists activate receptors to produce a response.
• The duration of drug effect involves how quickly it is removed from the body.
• Drug action can also be affected by drug affinity, with the greater the affinity, the better the drug action.
• Antagonists bind with receptors but do not activate them or cause a response, they can actually block the activation of receptors.
• Some drugs when absorbed from the stomach enter the portal circulation and pass through the liver, a process known as the first pass effect.
• Partial agonists produce a response, however, this is less than would be expected from a full agonistic drug.
• The phases in hepatic metabolism are uptake, distribution, and elimination.
• A cell receptor is a protein on the surface of a cell that binds to a specific drug.
• Receptor occupancy is the extent to which a receptor is occupied by a drug.
• Drugs affect the body by altering the function of various organs and systems.
• Examples of different cell receptors include G-protein coupled receptors, ion channels, and nuclear receptors.
• An ion channel is a protein in the cell membrane that allows or blocks the passage of ions.
• First pass metabolism is the process by which a drug is metabolized before it reaches the systemic circulation.
• Affinity is the term used to describe the strength of a drug's binding to its receptor.
• Drug metabolism can influence strength of dose and frequency of dosing, with drugs that are metabolized quickly having a short duration of action and needing to be administered more often, and drugs that are metabolized slowly having a longer duration of action and may only need to be given on a once-daily basis.
• Some drugs can displace others from their binding sites on the plasma proteins.
• Pharmacodynamics is the effect that drugs have on the body, while pharmacokinetics is the study of the way in which drugs move through the body during absorption, distribution, metabolism and excretion.
• Drug metabolites may have greater, lesser or similar pharmacological activity compared with the parent drug.
• Physiological factors relate to human physiological functions such as blood flow to the absorbing site and total surface area for absorption.
• Once a drug has been administered and absorbed, it must be distributed to its site of action.
• Pharmacokinetics influences decisions over the route of administration, as the processes that occur after drug administration can be broken down into four distinct areas: Absorption of the drug, Distribution of the drug molecules, Metabolism of the parent drug, and Excretion or elimination of the drug and its metabolites.
• For a weak acid, it does not dissociate as much if dissolved in an acid environment, meaning the drug can cross membranes in a more active form than if it had been dissolved in a neutral or base solution.
• The other factors that can affect the rate and reliability of drug absorption fall into two categories: physiological and physico-chemical.
• The extent of plasma protein binding can vary widely among drugs, with drugs bound to plasma proteins being pharmacologically inert and only free drugs being active.
• It is very important that the patient takes the medicine as directed by the prescriber to obtain the best therapeutic value from it, as a nurse, therefore, you need to understand the mechanics of absorption so that you can explain to the patient why it is important that a drug is taken in the correct way.
• Some drugs, such as iodine and thyroid gland, have specific tissues that take them up.
• Before a drug can begin to exert any effect on the body, it has to be absorbed into the body systems, with the most important factor being the route of administration.
• Some drugs are both weak acids and weak bases (alkalis), these drugs tend to dissociate when administered.
• For drugs to produce their effects, they must interact with the body, which can happen in many ways and depends on the properties of the drug.
• The biotransformation of drugs, which is the process of turning the parent drug into different compounds called metabolites, occurs mainly in the liver (hence the term hepatic metabolism).
• Some drugs are called pro-drugs, meaning the drug itself is pharmacologically inactive until it is metabolized by the liver to its active form.
• Many patients require the administration of their medication to be tailored to their particular medical condition or the medication that they have been prescribed, making it important that nurses understand the implications attached to choosing the route of administration of drugs based on their absorption, as it can impact on the patient’s ability or desire to take their medication.
• Once a drug has had its desired effect, it needs to be excreted by the body.