Any chemical the affects the physiologic processes of a living organism
the study of the science of drugs
the study of natural drug sources. Plants, Animals, Minerals
alkaloids are the most active component. react with acids to form a salt that is able to dissolve more readily in body fluids
usually end in “-in” (digoxin).
give the products the ability to attract and hold water (seaweed extracts, seeds with starch).
chief source is Pine Tree sap. Also acts as a local irritant or as a laxative and caustic agent.
- classified as volatile or fixed.
- Volatile oils – peppermint, spearmint and juniper.
- Fixed Oils - do not evaporate easily-castor oil, olive oil
body fluids or glands can be drug sources
insulin, steroids, etc
flu, measles, mumps, hepatitis B, etc.
provide inorganic materials not available from plants and animals. Used as they occur in nature or are combined with other ingredients ( iron, iodine, Epsom salts).
laboratory researchers have used traditional knowledge along with chemical science for the development of drugs. Most drugs produced today are made in laboratories. DNA research is also producing drugs (Human Insulin).
Naming of Drugs
- During the process of drug development a drug will acquire 3 different names: U.S. Pharmacopeia and the National Formulary are two primary sources of drug information.
- Chemical name – p-Isobutylhdratropic Acid
- Generic name – Ibuprofen
- Brand or trade name – Motrin, Advil, Pamprin, Nuprin.
is the study of how various dosage forms influence pharmacokinetics and pharmacodynamics. Different dosage forms have different pharmaceutical properties. Dosage forms determine the ability of a drug to move into solution, called DISSOLUTION. Actual breakdown of a dosage form occurs in the aqueous contents of the digestive tract. Once dosage form disintegrates or is dissolved, it is free to enter into a solution as a solute particle and is more available to the body.
- Aqueous preparations – dissolve in water
- Alcohol preparations – dissolve in alcohol
- Solid and semisolid preparations - suppositories, ointments, patches, tablets, capsules, etc.
- Liquids, elixirs, syrups-FASTEST
- Suspensions, solutions
- coated tablets
- enteric coated tablets-Slowest
Creams, lotions, Drops
- is the study of how the body deals with a drug. In determining the dosage, route and timing of a drug dose pharmacokinetics of the drug must be considered.
- Pharmacokinetics includes:
- 1. Absorption
- 2. Distribution
- 3. Metabolism
- 4. Excretion
is the movement of a drug from its site of administration into the bloodstream for distribution to the tissues.
the term used to express the extent of drug absorption, e.g. the enteral preparation of a drug is less bioavailable than the parenteral form of the drug.
if 2 drugs have the same bioavailability and the same concentration of active ingredients they are said to be bioequivalent.
the ability of a drug to dissolve and form a solution
It depends on the drugs chemical structure and is influenced by the cellular environment at the absorptive site.
necessary for any drug that must cross the lipid rich cell membrane.
- Drugs pass thru cell membrane in 3 ways:
- Through channels or pores – very few drugs pass this way.
- Aid of a transport system – may require energy
- Direct penetration of a cell membrane – most common and must be lipid soluble.
passage of drugs through cells pores. not efficient
can be efficient over a tiny distance from areas of high to low concentration
Active process, transport
requires energy. moves from low to high concentration
requires a carrier (insulin)
cell membrane engulfs the molecule
Factors which affect drug absorption
- -Food in the stomach and intestines
- -Rate of blood flow to the stomach/intestines
- -Acidity of stomach, alkalinity of the intestines
- -G. I. motility
- -First-Pass Effect
First Pass Effect
Oral Drugs are absorbed through the small intestine into the portal venous system that flows through the liver. The drugs are metabolized in the liver and some of the active drug will be inactivated or diverted before it can reach the general circulation and its intended site of action. First-Pass reduces the bioavailability of a drug to less than 100%. Some drugs which undergo First-Pass may have a bioavailability of 50% or less.
Drug Routes that undergo First-Pass
- Hepatic artery
- Portal Vein
Drug routes that do not undergo First-Pass
- Topical, including some rectal drugs
refers to the transport of a drug in the body by the bloodstream to its site of action. Three factors which determine movement of drugs throughout the body:
- Blood supply – the areas with the best blood supply receive the drug first.
- Ability to exit the vascular system.
- Ability to enter into the cell.
- Some portion of a drug binds to protein in the blood. The most common of these proteins is albumin. Once a portion of a drug binds to protein in the blood it is not free to produce its desired effect. However, the unbound portion of a drug can produce the desired effect. When 2 or more drugs are competing for binding sites on protein molecules more of each drug is available to the cells and may cause a drug-drug interaction.
- ONLY UNBOUND DRUG IS FREE TO PRODUCE A THERAPEUTIC AFFECT.
Volume of Distribution
describes various areas where drugs may be distributed. These areas can be blood, total body water, body fat or other body tissues and organs.
highly water soluble drugs have a small volume of distribution and high blood concentration and tend to stay in the blood. Produces a very slow onset of action.
highly fat soluble drugs have a large volume of distribution and low blood concentration. Chemically repelled by the high water content of the blood. Also cell membranes are mostly lipid soluble and fat molecules pass through these membranes more easily.
Blood Brain Barrier
is a protective system of cellular activity that keeps many things away from the CNS (foreign invaders, poisons). Drugs that are highly lipid soluble are more likely to pass through the blood-brain barrier and reach the CNS. Drugs used to treat diseases of the CNS must be highly lipid soluble to be effective.
also referred to as BIOTRANSFORMATION. Involves the biochemical alteration of a drug into an inactive metabolite, a more soluble compound, or a more potent active metabolite.
- -Liver- most responsible for the metabolism of drugs can occur in the plasma, kidneys and membranes of the intestines.
- -Enzymatic systems in the liver – Cytochrome P-450.
- -Factors that alter metabolism – genetic, diseases, medications, disease conditions.
the elimination of drugs from the body whether they are active, metabolized or unchanged all drugs must eventually be removed from the body.
- -The primary organs of excretion are the Kidneys.
- -The skin, lungs, bile, feces, liver and the bowel also eliminate some drugs.
the time it takes for none-half of the original amount of drug to be removed from the body. It is a measure of the rate at which drugs are removed from the body.
when a drug is taken in successive doses at intervals that are shorter than recommended or when the body is not able to eliminate a drug properly, the drug can accumulate in the body, leading to toxic levels and adverse effects.
the physiologic state in which the amount of drug removed via elimination is equal to the amount of drug absorbed. Steady state is reached in approximately 5 half-lives of administered drug.
the amount of a drug that is needed to cause a therapeutic effect.
Drugs whose effects may be needed quickly have a recommended higher loading dose. Usually used for drugs that take a prolonged period to reach a critical concentration.
after higher drug levels have been established with a loading dose, smaller doses of the drug are given to maintain the blood concentration of the drug.
Onset of Action
the time from drug administration to the first observable effect.
is the time required for a drug to reach its maximum therapeutic effect. Peak level is the highest blood level of a drug.
Duration of Action
is the length of time that the drug concentration is sufficient to elicit a therapeutic response.
is the lowest blood level of a drug.
Dose Response Curve
is the exact amount of a drug that is administered in order to produce a specific effect. When the relationship between the dose response is plotted as a graph, it is referred to as the dose-response curve.
is the measure of the strength or concentration of a drug required to produce a specific effect, e.g. Morphine 10mg vs. Dilaudid 1mg.
refers to the largest effect a drug can produce.
Factors influencing the body’s response to a drug
- physiologic factors
- pathologic factors
- genetic factors
- immunological factors
- psychological factors
- environmental factors
is the study of what drugs do to the body and how they do it.
Mechanism of Action or Therapeutic Effect
- -can produce actions (therapeutic effects) in several ways.
- -Can increase or decrease the rate at which a cell or tissue functions.
- -can modify the strength of a cells function
- -can not cause a cell to perform a function that is not a part of its natural function.
Drugs exert their actions in three ways
- Nonselective interactions
a drug binds to receptor sites on the cell and produce an action (see pf. 27, table 2-8)
drug binds to receptor and produces a response
drug binds to receptor, response diminished compared with that elicited by an agonist.
drug binds to receptor and produces no response. Drug prevents binding of agonists.
drug competes with agonist for binding site on receptor. If it binds, no response. This is a reversible reaction.
binds to the receptor sites and blocks the effects of the agonist, non-reversible reaction. Giving larger doses of the drug can not reverse its action.
are proteins that change the rate of chemical reactions without themselves being changed and without an external energy source. Enzymes catalyze nearly every biochemical reaction in a cell. Drugs either enhance or inhibit a cells action through its interaction with the cells enzyme system.
some drugs do not interact with receptors or enzymes. These drugs affect cell membranes and various cellular processes which alter metabolic activities. These drugs can alter physically or chemically there cellular processes.
- is the study of the use of drugs in the treatment of disease
- Assess for: present drug therapy, prescribed drugs, OTC drugs. street/illicit drugs.
Acute Drug Therapy
intensive drug treatment, implemented in acutely ill. often used to sustain life or treat disease
prevents progression of a disease or condition, maintains limits, or controls actions.
supplies body with a substance needed to maintain normal function. may be because body does not produce it or it is made is insufficient quality
- provides comfort, pain relief.
- often used in end stages of an illness
maintains the integrity of body functions while the patient is recovering from illness or trauma
drug therapy provided to prevent illness based on scientific research
drug therapy providerd to prevent illness based on experience
evaluation must be done to determine the patient’s clinical response to the drug. All drugs are potentially toxic and can have cumulative effects.
– the ratio of the drugs toxic level to the level that provides therapeutic benefits. The safety of a drug is determined by the Therapeutic index.
- ·Low-therapeutic index – difference between the therapeutic dose and toxic dose is small. May cause an adverse reaction.
- ·High therapeutic Index – difference between the therapeutic dose and toxic dose is greater.
certain drug levels are associated with therapeutic responses and some drug levels are associated with toxic levels.
concurrent diseases or other medical conditions may impact the patient’s response to drug therapy
when the body becomes accustomed to a particular drug over a period of time, the response is decreased.
occurs when an individual needs a drug to function normally, can be physiological (physical dependence) or psychological (addiction)
Cross Tolerance/Cross Dependence
occurs when tolerance or dependence develops to different drugs which are chemically related, Heroin -> Morphine.
occurs when a drug is no longer administered to a dependent patient; barbiturates, benzodiazepines. Symptoms – N/V, tremors, seizures, etc
when 2 drugs with similar actions are given together in smaller doses to produce an effect equal to one of the drugs at a higher dose. The 2 drugs are given in smaller doses thus avoiding a toxic reaction, but providing good pain relief
ex. perk 5
the response elicited by combined drugs is GREATER THAN the effect of each drug given separately. Two antibiotics may be given to fight infection more effectively than one antibiotic, e.g. Vancomycin + Flagyl.
a drug inhibit the effect of another drug, e.g. antacids inhibit some antibiotics.
occurs when 2 parenteral drugs or solutions are mixed together and results in chemical deterioration of one or both drugs, e.g. furosemide and heparin. Heparin is never mixed with another drug
Adverse Drug Events (ADE)
any reaction to a drug that is not expected. A broad term to describe and adverse outcome of drug therapy in which a patient is harmed due to internal (body) or external (staff errors) factors. ADRs can be preventable or non-preventable. MOST COMMON ADE IS A MEDICATION ERROR. (See pages 62-63 in Lilley for Nursing measures to prevent medication errors).
Adverse Drug Reaction (ADR)
- any reaction to a drug that is unexpected and occurs at therapeutic dosages. Less predictable and may or may not be preventable. There are 4 general categories of ADR:
- Pharmacologic reactions
- Hypersensitivity (allergic) reactions
- Idiosyncratic reactions
- Drug Interactions
Food and Drug Administration Program that monitors and assesses the incidence of adverse reactions. Reports can be faxed to 1-800-FDA-0178.
a drug used to treat a disease may be more effective than desired, e.g. antihypertensive drug lowers B/P to the point that the patient may faint.
an allergic reaction involves the patient’s immune system which can result in a mild rash to anaphylaxis, a life-threatening reaction with airway constriction cause by bronchospasms, tachycardia and cardiovascular collapse which may result in death. If a patient begins to exhibit signs of anaphylaxis after receiving a medication maintain the airway and call for help immediately. Always check for allergies before administering any drug to a patient. A person cannot be allergic to a drug that they have never taken, but they can have cross allergies within the same drug class.
sensitivity to one group of drugs may cause a cross sensitivity to another group of drugs that are chemically similar, e.g. penicillin -> cephalosporin
if a patient begins to exhibit signs of anaphylaxis after receiving a medication maintain the airway and call for help immediately. Symptoms of anaphylaxis may include: rapid onset, sweating, feeling of apprehension, tightness in throat, bronchospasms, tingling in mouth, face or throat, itching, weakness, loss of consciousness
is an unexpected and unpredictable reaction to a drug. It is a genetically determined abnormal response to a drug, (see boxes, pg 31, 2-3, and 2-4).
Unintentional adverse effects that occur during treatment.
expected, well-known reactions resulting in little or no change in the patient’s management. The presence of side effects may not be a reason for the prescriber to stop a medication. Side effects generally disappear with time.
may threaten life. It can result from a single ingestion of a large amount of a drug such as an overdose. If a patient is exhibiting toxic effects of a medication, DO NOT administer the next scheduled dose and notify the prescriber
drug induced birth defects
drugs can cause genetic mutation by changing a cell’s DNA
some drugs have cancer causing effects
the drug attached to a cell site is perceived as an antigen and is attacked by antibodies in the blood destroying the cell. This reaction takes place over time, several days->hives, rash, difficulty breathing, increased B/P and HR, dilated pupils, diaphoresis, “panic” feeling, and respiratory arrest. The drug must be stopped immediately and the prescriber notified
Serum Sickness Reaction
appears 2-3 weeks post ingestion of a drug->fever, rash, joint pain, and enlarged spleen. Stop drug and notify prescriber.
Delayed Allergic reaction
occurs several hours after exposure and involves antibodies that are bound to specific white cells-> rash, hives, swollen joints, edema of the face and limbs. Notify prescriber
a rash that is usually caused by an immune response to drugs. It may express itself on the skin in “multiforme” ways, including macules, papules, blisters, and hives. It may involve the palms and soles, the mucous membranes, the face and extremities. In the extreme form, which may be fatal, when the eyes, mouth and internal organs are involved it is called Stevens-Johnson Syndrome or Toxic Epidermal Necrolysis (30%-40% mortality).
The nurse is responsible for checking all clinical responses to medication, both positive and negative, document and report to prescriber. Remember the Mantra, “ If it hasn’t been documented it hasn’t been done”.
no medication, including OTC or herbal remedies, other than those prescribed by the physician, should be taken by a pregnant woman. In some cultures certain herbs may be taken by the pregnant woman because it is the norm for the culture.
Controlled Substance Schedule
- C-1 – high abuse potential
- C-11 – high abuse potential
- C-111 – less than C-1
- C-1V – less than C-111
- C-V – less than C-1V
- careful explanation of purpose of a study.
- describes procedures used and risks involved.
- Informed volunteer’s uninformed or coerced subjects.
examines the effects of drugs on specific ethnicities (table 4-4, pg. 54).
refers to the effect of patient’s age, gender, size, body composition and other characteristics on pharmacokinetics
General Teaching, Learning Principles
- patient centered
- assess readiness to learn
- patient’s ability to learn
- literacy level
- use of pictures, demonstrations, return demonstrations
- interpreters for non-English speaking patients
- family support
- keep it simple
- resources for up to date information
Patient/Family teaching of medications
- name, dose, action of drug
- timing of administration
- specific OTC drugs or alternative therapies
- specific comfort or safety issues
- safety measures
- specific points about drug toxicity
- specific warnings about drug discontinuation
- follow institutional policies
- do not assume that adequate teaching has occurred
- begin discharge teaching as soon as possible
- minimize distractions
- evaluate teaching
- use social service and/or discharge planner for follow-up
- document teaching/learning strategies
Classified according to site of action in the kidneys. Remove excess fluid from the body.
- -Indications – control B/P
- -Loop diuretics – most potent, used mainly for CHF and renal disease, monitor electrolyte especially KCL, e.g. Furosimide (lasix).
- -Potassium sparing diuretics – removes excess fluid while preserving KCL, e.g. Spironolactone.
- -Thiazides – cheapest and most commonly used. Long half-life. Dosing generally once a day, e.g. Hydrochlorothiazide (HCTZ)
Indications – prevention and treatment of constipation and bowel preparation for radiologic or endoscopic procedures.