PHARMACOLOGY

Ms. Corazon B. Guanco. RN, MANInstructor

Attendance Recitation 10% Attitude

Quizzes ------ 25%

Assignments Requirements 25%

Major Exams--- 40% Total ------------ 100%

Grading System

Origin & definition: Pharmacology (Greek pharmakon,

drugs, and logos, science) deals with the study of drugs and their actions on living organisms.

Therapeutic Methods --these are approaches to therapy

given in different ways in treating diseases.

****Examples of Therapeutic methods are:***

*Drug therapy: treatment with drugs * Diet therapy: treatment by diet (low salt-

diet for patients with cardiovascular disease)• Physiotherapy: treatment with natural

physical • Forces such as water, light & heat.• * Psychologic therapy: identification of

stressors and methods to reduce or eliminate stress and/or the use of drugs.

DRUGS Drugs (Dutch droog, meaning dry) are

chemical substances that have an effect on living organisms.

Therapeutic drugs (medicines) are those drugs used in the prevention or treatment of diseases.

DRUG NAMES Chemical Name—the chemical constitution of the drug & the exact placing of its atoms and molecular groupings.Generic Name (Nonproprietary Name)-common name—given before a drug becomes official--the first letter of the generic name is not capitalized

Official Name—is the name under which the drug is listed by the FDA (USA) or BFAD(Phil)

Trademark (Brand Name)—this indicates that that the name is registered and its use is restricted to the owner of the drug, who is usually the manufacturer.

The first letter of the trade name is capitalized. Example: Chemical name: 4-Thia-1-azabicyclo/3.20heptane -2-carbocyclic acid,-6-(aminophenylacetyl) amino-3 -3-dimethyl-7-oxo- Generic name: Ampicillin Official name: Ampicillin, USP Brand names: Polycillin, Principen

1. According to which body system they affect (e.g. drugs affecting the central nervous system,

drugs affecting the cardiovascular system, or drugs affecting the gastrointestinal system)

2. By their therapeutic use or clinical indications (e.g. antacids, antibiotics, antihypertensives, diuretics,

laxatives) 3. Using the physiologic or chemical action (e.g. anticholinergics, beta adrenergic blockers,

cholinergics) 4. Prescription or nonprescription (OTC drugs)

DRUG CLASSIFICATIONS

* Adrenergics Cholinergics Hypnotics Anesthetics decongestants hypoglycemics Antibiotics diuretics laxatives Antihistamines electrolytes sedatives Antihypertensives emetics tranquilizers Antitussives expectorants

vasoconstrictors Cardiotonics hormones vasodilators

DRUG CLASSIFICATIONS SUBCATEGORICALLY

Ex. Aspirin—relieves pain (analgesic) --to reduce fever

(antipyretic) --to reduce inflammation

of tissues ( anti-inflammatory)

Ex, Flexeril —relieve muscle spasm (muscle relaxant)

Indications. A list of medical conditions or diseases for which the drug is meant to be used.

(Ex. Diphenhydramine hydrochloride{ Benadryl}

Indication include allergic rhinitis, motion sickness

Actions. A description of the cellular changes that as a result of the drug (Ex. Benadryl –an antihistamine)

TERMS INDICATING DRUG ACTIONS

Contraindications. A list of conditions for which the drug should not be given.(Ex. Not given for pregnant or lactating mothers)

Cautions. A list of conditions or type of patients that need close observation for specific side effects when given the drug. (EX. Benadryl should be given with caution to patients with history of bronchial asthma or hypertensions

A list of unpleasant or dangerous secondary effects , other than the desired effect

Side Effects or Adverse Reaction

Ex. Side effects of Benadryl : sedation. dizziness, anorexia, thickening of bronchial secretions

Ototoxicity causes damage to the 8th cranial nerve resulting in impaired hearing or ringing in the ears(tinnitus)

Side effects or adverse reactions can

include

causes damage to the kidneys, resulting in impaired kidney function, decreased output, and renal failure.

Nephrotoxicity

is an increased reaction to sunlight, with the danger of intense sunburn

Photosensitivity

A list of other drugs or foods that may alter the effect of the drug & usually should not be given during the same course of therapy

Interaction

Will intensify the effects of Benadryl

(MAO are drugs used to treat depression)

Ex. Monoamine Oxidase{MAO}

Sources of Drugs

Example Trade Name

Classification

Plants

Cinchona Bark

Poppy Plant

Quinidine

Digitalis

Morphine

AntiarrythmicCardiotonic

Analgesic

Minerals

Magnesium

Zinc

Gold

Milk of Magnesia

Zinc Oxide Ointment

Auranolin

AntacidLaxative

Zinc Protectant

Anti inflammatory UsedIn the treatment of rheumatoid arthritis

Animals Thyroid Gland of AnimalsPancreas of cow, Hog

Stomach of cow/hogThyroid gland of Animals

Thyroid USP

Insulin regular, NPH

Pepsin

Thyroid USP

Hormone

Antidiabetic Hormone

Digestive Hormone

Hormone

Synthetic Meperidine

Diphtnoxylate

Co-trimoxazole

Demerol

Lomotil

BactrimSeptra

Analgesic

Antidiarrheal

Anti-infectiveSulfonamide used for the treatment of UTI

SOURCES OF DRUG STANDARDS

CANADA Official drug—pertains to any drug for which

a standard is described in any publication for drugs in Canada.( chemical & generic names of medicines are the same in both Canada & the US)

*The United States Pharmacopoeia (USP) * National Formulary (NF) * European Pharmacopoeia * British Pharmacopoeia * Canadian Formulary

UNITED STATES * The United States

Pharmacopeia * National Formulary * American Drug Index * The American Hospital

Formulary Service Drug Information

* Physician’s Drug Reference(PDR)

1. Drugs do not create new

responses, but alter existing physiology (ex) an antihypertensive agent is successful if the patient’s blood pressure is lower during therapy than before therapy.

Basic Principles of Drug Action

2. Drugs interact with the

body in several different ways . The drug forms chemical bonds with specific sites called receptors.

Pharmacodynamics—the

study of the interactions between drugs & their receptors & the series of events that result in a pharmacologic response.

3. Most drugs have several

different atoms within each molecule that interlock within various locations on a receptor. The better the fit between the receptor and the drug molecule , the better response.

4. Drugs that interact with a receptor to

stimulate a response are known as agonists. Drugs that attach to a receptor but do not stimulate a response are called antagonists. Drugs that interact with a receptor to stimulate a response but inhibit other responses are called partial agonists.

5. All drugs go through 4 stages :

absorption, distribution, metabolism, excretion (ADME)

1. Systemic effect—reaches

widespread areas of the body (Ex. Acetaminophen (Tylenol) suppository , although given rectally ,has the ability to be absorbed and distributed throughout the body to cause a general reduction in fever and pain.

EFFECTS of DRUGS

--is limited in the area of the body where it is administered.(Ex. Dibucaine ointment applied rectally affects only the rectal mucosa to reduce hemorroidal pain.

2. Local Effect

Pharmacokinetics—the

study of the mathematical relationships among the absorption, distribution, metabolism, & excretion of individual medicines over time.

1. Absorption—getting into the blood

stream 2. Distribution—moving from the

bloodstream into the tissues and fluids of the body

3. Metabolism—Physical & chemical alterations that a substance undergoes in the body

4. Excretion—Eliminating waste products of drug metabolism from the body

4 DRUG PROCESSES

The site of absorption of drugs are

varies according to ff. physical properties of each drug

1. pH. Drugs of a slightly acidic nature (e.g. Aspirin & tetracycline) are absorbed well through the stomach mucosa. Drugs of an alkaline pH are not absorbed well through the stomach, but are readily absorbed in the alkaline environment of the small intestine

ABSORPTION

Substances high in lipid solubility are quickly &

easily absorbed through the mucosa of the stomach.

Alcohol & substances containing alcohol are soluble in lipids.They are rapidly absorbed in the GI tract.

Substances liw in lipid solubility are not absorbed well through the stomach and are absorbed best when given by other means other than the GI tract.

2. Lipid (Fat) Solubility

Food in the stomach tends to slow

absorption due to a slower emptying of the stomach. If a fast drug effect is desired, an empty stomach will facilitate quicker absorption.( Give before meals or take with food to decrease side effects. (e.g. nausea & gastric ulcers ) on the GI tract.

3. Presence or absence of food in

the stomach

The movement of the drug from the

bloodstream into the tissues & fluids of the body is also affected by the specific properties of the drug. Some dtugs pass the “blood-stream barrier” or the “placental barrier” whereas others do not.( Drugs contraindicated for lactating mothers because the drug has the ability to pass through the cell membranes into the milk.)

DISTRIBUTION

Some drugs have a selective

distribution. This refers to an affinity or attraction of a drug to a specific organ or cells.(Ex. Amphetamines have a selective distribution to CSF. The human chorionic gonadotropin (HCG) hormone, which is used as a fertility drug , has a selective distribution to the ovaries.)

Cont.

When transformed in the liver

(biotransformation) a drug is broken down & altered to more water soluble by products.; thus the drug maybe more excreted by the kidney.

Cumulative effect—is an increased effect of

a drug when repeated doses accumulate in the body. If unnoticed the cumulative effect may build to a dangerous or toxic level.

METABOLISM

=refers to a condition that results from

exposure to either a poison or a dangerous amount of a drug that is normally safe when given in a smaller amount.

Digoxin is a cardiac drug that must be given cautiously because of its potential for causing a cumulative effect . Digoxin slows the heart rate .Circulation & renal function must be adequate.

Toxicity

-the amount of time required for

50% of the drug to be eliminated from the body.

(Ex. If a patient is given 100 mg of a drug that has a half-life of 12 hrs. the following would be observed:

Half-Life

Age Metabolism % excretion are slower in older adults

and therefore attention must be given to possible cumulative effects.

Weight Generally, the bigger the person, the greater the

dose Should be. Many drugs are calculated on the basis

of the patient’s weight.

VARIABLE FACTORS INFLUENCING DRUG ACTION

Women respond differently than

men to some drugs. The ratio of fat per body mass differs, & hormone levels. If the female is pregnant or nursing, most drugs are contra indicated or the dosage must be adjusted.

sex

The more positive the patient feels about

the medication he/she is taking the more positive the physical response. This is called the placebo effect.

Placebo—is an inactive substance that resembles a medication, although no drug is present.

Psychological State

Synergism. the action of two drugs working together in

which one helps the other simultaneously for an effect that neither could produce alone. Drugs working together are said to be synergistic.

Potentiation The action of two drugs in which one prolongs

or multiplies the effect of the other.

Terms Used to Describe Drug

Interaction

Antagonism The opposing action of two drugs in which one

decreases or cancels out the effect of the other.

Desirable Synergism: Promethazine (Phenergan) (a non narcotic sedative) and meperidine (Demerol) (a narcotic analgesic) are very effective in relieving pain. By giving small amounts of each together, pain can be relieved more safely than by giving large amount of Demerol.

Antagonism

Undesirable synergism Ex. Sedatives & barbiturates given in

combination can depress the CNS to dangerous levels, depending on the strengths of each

Desirable potentiation To build up a high level of some forms of

penicillin (an antibiotic) in the blood, the drug probenecid (Benemid )(antigout medication) can be given simultaneously. Benemid potentiates the effect of penicillin by slowing the excretion rate of the antibiotic.

Toxic effect may result when cimetidine ( Tagamet) ( a gastric antisecretory) is given simultaneously with Tofranil (an antidepressant). Tagamet potentiates the level of antidepressant concentrations in the blood.

Desirable antagonism. A narcotic antagonists (e.g. naloxone, Narcan saves lives from drug

overdoses by cancelling out the effect of narcotics.

Undesirable antagonism. Antacids taken at the same time as tetracycline after the pH and prevent absorption of tetracycline.

Undesirable potentiation

--the amount of drug given for a particular

therapeutic or desired effect. 1. Minimum dose. Smallest amount of a drug

that will produce a therapeutic effect. 2. Maximum dose. Largest amount of a drug

that will produce a desired effect without producing symptoms of toxicity.

3. Loading dose. Initial high dose(often maximum dose) used to quickly elevate the level of the drug in the blood

DOSAGE

4. Maintenance dose. Dose required to

keep the drug blood level at a steady state in order to maintain the desired effect.

5. Toxic dose. Amount of a drug that will produce harmful side effects or symptoms of poisoning

6. Lethal dose. Dose that causes death 7. Therapeutic dose. Dose that is

customarily give (adult dose based on body weight of 150 lb.) adjusted according to variation from the norm.