PHARMACOKINETICS & DYNAMICS (2nd ppt) Flashcards by hhshsjwy, pmmmamnhwg

how the drug affects the body

Pharmacodynamics

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how the body acts on the drug

Pharmacokinetics

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is the study of the interactions between the chemical components of living systems
and the foreign chemicals, including drugs that enter those systems.

PHARMACODYNAMICS

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Drugs usually work in one of four ways:

To replace or act as substitutes for
missing chemicals
To increase or stimulate certain cellular activities
To depress or slow cellular activities
To interfere with functioning of foreign
cells, such as invading
microorganisms or neoplasms leading

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• Specific areas on cell membranes
• They react with certain chemicals to cause an effect within the cell

Receptor Sites

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Enzymes break down the reacting chemicals and open the _____ for further stimulation

receptor site

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Interact directly with receptor sites to cause the same activity that natural chemicals would cause at that site

AGONISTS

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Prevent breakdown of natural chemicals that are stimulating the receptor site

INHIBITORS

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React with receptor sites to block normal stimulation, producing no effect

COMPETITIVE ANTAGONIST

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React with specific receptor sites on a cell and by reacting there prevent the reaction of another chemical with a different receptor site on that cell

NON COMPETITIVE ANTAGONIST

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Molecules of drug A react with specific
receptor sites on cells of effector organs
and change the cells’ activity

Agonist interaction with receptor site
on cell.

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Drug A and drug C have an affinity for
the same receptor sites and compete
for these sites; drug C has a greater
affinity, occupies more of the sites, and
antagonizes drug A.

Competitive antagonism.

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Drug D reacts with a receptor site that is
different from the receptor site for drug
A but still somehow prevents drug A
from binding with its receptor sites.

Noncompetitive antagonism

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Drugs also can cause their effects by interfering with the enzyme systems that act as catalysts for various chemical reactions.

Drug Enzyme Interaction

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Enzyme systems work in a cascade fashion, with one enzyme activating another, and then that enzyme activating another, until a ______ eventually occurs.

cellular reaction

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The ability of a drug to attack only those
systems found in foreign cells

Selective Toxicity

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(how long it will take to see the beginning of the therapeutic effect)

onset of drug action

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(how long it will take to see the maximum effect of the drug)

timing of the peak effect

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(how long the patient will experience the drug effects)

duration of drug effects

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The amount of drug that is needed to cause a therapeutic effect

Critical Concentration

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A higher dose than that usually used for treatment to reach critical concentration quickly

Loading Dose

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Dynamic Equilibrium Processes:

• Absorption from the site of entry
• Distribution to the active site
• Biotransformation (metabolism) in the liver
• Excretion from the body

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Refers to what happens to a drug from the time it is introduced to the body until it reaches the circulating fluids and tissues

ABSORPTION

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Drug absorption is influenced by the _____

route of administration

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• Major process through which drugs are absorbed into the body • Occurs across a concentration gradient • Movement from an area of greater concentration to lower concentration

Passive diffusion

Process that uses energy to actively move a molecule across a cell membrane

Active Transport

Involves movement through pores in the cell membrane either down a concentration gradient or as a result of the pull of plasmaproteins

Filtration

Process of Absorption:

Passive Diffusion Active Transport Filtration

Involves the movement of a drug to the body’s tissues

DISTRIBUTION

Factors that affect drug distribution:

• Drug’s lipid solubility and ionization • Perfusion of the reactive tissue

Is a protective system of cellular activity that keeps many things away from the CNS.

Blood Brain Barrier

Drugs that are ______ are more likely to pass through the blood brain barrier and reach the CNS.

highly lipid soluble

Drugs that are ______ are not able to pass the blood brain barrier.

not lipid soluble

Many drugs pass through the placenta and affect the developing fetus in pregnant women.

Placenta and Breast Milk

The process by which drugs are changed into new, less active chemicals.

METABOLISM (BIOTRANSFORMATION)

The _____ deliver these absorbed molecules into the liver, which immediately transforms most of the chemicals delivered to it by a series of liver enzymes.

portal veins

These enzymes break the drug into metabolites, some of which are deactivated and can be readily excreted from the body.

liver enzymes

Is the removal of a drug from the body.

EXCRETION

Routes of excretion

• Skin, saliva, lungs, bile and feces • Excreted by the kidneys through glomerular filtration

is the time it takes for the amount of drug in the body to decrease to one half of the peak level it previously achieved.

half life

_____ may arise because of increased biotransformation of the drug, increased resistance to its effects, or other pharmacokinetic factors. When this occurs, the drug no long causes the same reaction. Therefore, increasingly larger doses are needed to achieve a therapeutic effect.

Tolerance

If a drug is taken in successive doses at intervals that are shorter than recommended, or if the body is unable to eliminate a drug properly, the drug can accumulate in the body, leading to toxic levels and adverse effects.

cumulation

When two or more drugs or substances are taken together, there is a possibility that an ______ can occur, causing unanticipated effects in the body.

interactions

When two or more drugs or substances are taken together, there is a possibility that an ______ can occur, causing unanticipated effects in the body.

interactions

Are undesired effects that may be unpleasant or even dangerous.

ADVERSE EFFECTS

Development of adverse reaction from simple overdose which can be caused by individual response to the drug, high or low body weight, age or underlying pathology that alters the effects of the drug

Primary Action

This type of adverse effect can be avoided by monitoring the patient carefully and adjusting the prescribed dose to fit that particular patient's needs.

Primary Action

Effects of the drug in addition to the desired pharmacological effect.

Secondary Action

Excessively responsive to either the primary or the secondary effects of a drug. It may result from pathological or underlying condition.

Hypersensitivity

Occurs when the body forms antibodies to a particular drug, causing an immune response when the person is reexposed to the drug.

DRUG ALLERGY

Four main classifications of drug allergy

• Anaphylactic reactions • Cytotoxic reactions • Serum sickness • Delayed reactions

This allergy involves an antibody that reacts with specific sites in the body to cause the release of chemicals, including histamine, that produce immediate reactions (mucous membrane swelling and constricting bronchi) that can lead to respiratory distress and even respiratory arrest.

ANAPHYLACTIC Reaction

This allergy involves antibodies that circulate in the blood and attack antigens (the drug) on cell sites, causing death of that cell. This reaction is not immediate but may be seen over a few days

CYTOTOXIC Reaction

This allergy involves antibodies that circulate in the blood and cause damage to various tissues by depositing in blood vessels. This reaction may occur up to 1 wk or more after exposure to the drug.

SERUM SICKNESS REACTION

This reaction occurs several hours after exposure and involves antibodies that are bound to specific white blood cells.

DELAYED ALLERGIC REACTION

Inflammation of the mucous membranes, can occur because of a direct toxic reaction to the drug or because the drug deposits in the end capillaries in the mucous membranes, leading to inflammation

Stomatitis

Infections caused by organisms that are usually controlled by the normal flora

Superinfections

Bone marrow suppression caused by drug effects. This occurs when drugs that can cause cell death ( antineoplastics , antibiotics) are used.

Blood Dyscrasia

Potentially serious reactions to a drug

Toxicity

Low serum glucose concentration

Hypoglycemia

Low serum potassium levels

Hypokalemia

Damage to the tiny blood vessels of the retina

Ocular Damage

Affects dopamine levels in the brain

Parkinson like Syndrome

A generalized syndrome that includes high fever

Neuroleptic Malignant Syndrome

Drugs that affect the developing fetus or embryo which may cause death or congenital defects

Teratogenicity

It must include information on the history of past illnesses and the current complaint, as well as a physical examination; this provides a database of baseline information to ensure safe administration of a drug and to evaluate the drug’s effectiveness and adverse effects.

Nursing assessment

are developed from the information gathered during the assessment phase of the nursing process. It states the actual or potential response of a patient to a clinical situation

Nursing diagnoses

involves taking the information gathered and synthesized into nursing diagnoses to plan the patient care. This process includes determining the desired patient outcomes, setting goals for safe and effective drug administration, providing comfort measures to help the patient cope with the therapeutic or adverse effects of a drug, and providing patient and family education to ensure safe and effective drug therapy

Implementation

is part of the continuing process of patient care that leads to changes in assessment, diagnosis, and intervention. The patient is continually evaluated for therapeutic response, the occurrence of adverse drug effects, and the occurrence of drug drug, drug food, drug alternative therapy, or drug laboratory test interaction

Evaluation

Helps to determine whether the recommended drug dose is appropriate

Weight

The specific parameters that need to be assessed depend on the disease process being treated and on the expected therapeutic and adverse effects of the drug therapy.

Physical Parameters related to Disease or Drug Effects

Three types of nursing interventions are frequently involved in drug therapy:

• drug administration • provision of comfort measures • patient/family education.

The anticipation that a drug will be helpful (placebo effect) has proven to have tremendous impact on the actual success of drug therapy. Therefore, the nurse’s attitude and support can be a critical part of drug therapy. For example , a back rub, a kind word, and a positive approach may be as beneficial as the drug itself

Placebo effect