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PHARMACOLOGIC PRINCIPLES : 

1 PHARMACOLOGIC PRINCIPLES ---in other words--- All about the science of drugs Lecture 1 Part 2

Pharmacologic Principles : 

2 Pharmacologic Principles Drug Any chemical that affects the physiologic processes of a living organism Pharmacology The study or science of drugs

Pharmacologic Principles and the Nurse : 

3 Pharmacologic Principles and the Nurse Knowledge of pharmacologic principles will help the nurse better understand the therapeutic benefits and the potential toxicity of drug therapy - why a drug is ordered - how to manage drugs The nurse with a sound knowledge base in pharmacology is better equipped to implement the nursing process

Pharmacologic Principles : 

4 Pharmacologic Principles Pharmaceutics Pharmacokinetics Pharmacodynamics Pharmacotherapeutics Pharmacognosy Toxicology

Pharmacologic Principles : 

5 Pharmacologic Principles Pharmaceutics The study of how various drug forms influence pharmacokinetic and pharmacodynamic activities -Deals with the delivery system: iv, po, im -how the drug gets to the patient with the best response and the least adverse effects

Pharmacologic Principles : 

6 Pharmacologic Principles Pharmaceutics Chapter 2 Page 17 in your text has a diagram of the phases of drug activity -- the pharmaceutical phase (phase 1) is concerned with the disintegration of the dosage form or dissolution of the drug in the body -- how the dosage forms affect the way the body metabolizes the drug and how the drug affects the body

Pharmacologic Principles : 

7 Pharmacologic Principles Can you think of different forms of drugs??

Pharmacologic Principles : 

8 Pharmacologic Principles The dosage form determines the rate at which a drug enters the body A variety of dosage forms are available to increase the accuracy of dosing and to obtain therapeutic responses with the least amount of adverse effects

Pharmacologic Principles : 

9 Pharmacologic Principles Pharmaceutics Pharmacokinetics Pharmacodynamics Pharmacotherapeutics Pharmacognosy

Pharmacologic Principles : 

10 Pharmacologic Principles Pharmacokinetics The study of what the body does with a drug 1.Absorption- movement of a drug from the site of administration 2. Distribution- transport of a drug in the bloodstream 3. Metabolism- alteration of a drug in the body 4. Excretion- elimination of the drug or its compound from the body

1. Absorption : 

11 1. Absorption The ROUTE of administration affects the rate and extent of absorption of that drug A. Enteral (GI tract) B. Parenteral C. Topical KEY POINT when we are talking absorption— not all drug formulations are created equal

Absorption of oral drugs : 

12 Absorption of oral drugs Factors that affect absorption --varies according to the dosage form and route Food or fluids administered with the drug help or hinder absorption food may delay transit to the intestines or, high fat foods may help some fat soluble drugs Dosage formulation tablets, capsules- some dissolve in the stomach, others in the intestine. Certain types are coated to disolve slowly and have timed release. Some types are formulated with small particles that dissolve super fast- ie: micronized glyburide

Absorption of oral drugs (con’t) : 

13 Absorption of oral drugs (con’t) Factors that affect absorption --varies according to the dosage form and route Status of the absorptive surface portions of the small intestine may be missing or damaged Rate of blood flow to the small intestine blood flow may be decrease to the intestine in certain instances ie. sepsis, exercise, labor Acidity of the stomach food increases gastric acid production leading to decreased stomach PH. Drugs are formulated to dissolve at a specific PH level. Status of GI motility Fast or slow transit time due to pathology, conditions, or other medications change transit time

1. Absorption of oral drugs : 

14 1. Absorption of oral drugs Some drugs need to be taken on an empty stomach with a full glass of water Other drugs should be taken on a full stomach or with food to enhance absorption or minimize gastric irritation

1. Absorption of oral drugs : 

15 1. Absorption of oral drugs Drugs given by the oral route are absorbed into the mesenteric blood system and go to the liver for biotransformation before traveling on to the general systemic circulation. This is called the FIRST PASS EFFECT Therefore some of the drug is inactivated and not all will be available for use at its intended site of action. Drugs are formulated to account for this difference in availability to the tissues- called (bioavailability) This is why different forms of drugs are not equal ( see pg 18- Ch 2)

1. Absorption of parenteral drugs : 

16 1. Absorption of parenteral drugs Intravenous (fastest delivery into the blood circulation) Intramuscular Subcutaneous Intrathecal Intraarticular Intradermal Transdermal- can be considered parenteral too

1. Absorption of parenteral drugs : 

17 1. Absorption of parenteral drugs Parental drugs have no first pass effect Intravenous rapid and 100% bioavailable Avoids problems with stomach acid and intestinal absorption issues Intramuscular not as rapid as IV- will absorb better if there is a good blood supply Some IM medications are in DEPOT form- have a very slow absorption time (even months)- due to the formulation these drugs they should not be given IV- can cause an embolus

1. Absorption of topical drugs : 

18 1. Absorption of topical drugs Avoids the first pass effect Skin (including transdermal patches) Eyes Ears Nose Lungs (inhalation) Rectum- can have some first pass effect Vagina

1. Absorption of topical drugs : 

19 1. Absorption of topical drugs Many different formulations of Topical drugs May be given for local or systemic effect All have different designs for absorption Gels and ointments- erratic absorption Lotions Patches- absorption at different rates Drops- eyes and ears Nasal sprays- Suppositories Inhalers

1. Absorption - Routes : 

20 1. Absorption - Routes Remember: The ROUTE of administration affects the rate and extent of absorption of that drug

Pharmacologic Principles : 

21 Pharmacologic Principles Pharmacokinetics The transport of a drug in the body by the bloodstream to its site of action 1. Absorption 2. Distribution 3. Metabolism 4. Excretion

2. Distribution : 

22 2. Distribution Drugs are distributed first to areas that have extensive blood supplies heart liver kidneys brain Areas of slower distribution are muscles skin fat Sites like bone and brain may be very difficult for drugs to reach due to either poor blood supply or barriers

2. Distribution of drugs : 

23 2. Distribution of drugs Factors that affect distribution Protein-binding -Many drugs bind to proteins in the bloodstream -Albumin is the main protein to bind with drugs -Drugs bound to proteins are not available for use *called protein bound -Drugs not bound to protein are available to act at the intended site of action and exert their effects *called free drug Drug companies know this and adjust dosages

2. Distribution of drugs : 

24 2. Distribution of drugs Factors that affect distribution If a patient has low albumin- more free drug is available and the patient may have more adverse effects or become toxic If 2 drugs are given that are highly protein bound one of the drugs may reach higher free levels and the patient may have more adverse effects or become toxic - like musical chairs for binding sites

2. Distribution of drugs : 

25 2. Distribution of drugs Factors that affect distribution Water soluble vs. fat soluble drugs - drugs that are water soluble tend to stay in the bloodstream and have slow absorption into the tissues. - drugs that are fat soluble are distributed to the tissues more quickly

2. Distribution of drugs : 

26 2. Distribution of drugs Factors that affect distribution Blood-brain barrier -network of capillaries that makes it more difficult for drugs to pass through--will allow some fat soluble drugs to pass through Placental barrier -in general the fetus gets what mom gets

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