Pharmacology Basics

1. Pharmacology Basics Adapted from NurseCE4less.com for Ambercare Corporation Education Department, 2014

2. Describe the role of receptors related to medications • Discuss the four components of pharmacokinetics • Describe how medications are classified • Identify medication classifications, actions, uses, adverse reactions, side effects, contraindications and implications OBJECTIVES

3. HOW Tylenol knows to go to your head when you have a headache and to your elbow when you have “tennis elbow”? • OR how one or two small tablets containing only 500-1000 mg of active drug can relieve a headache or ease the inflammation from a strained muscle or tendon in a 185 pound athlete? DID YOU EVER WONDER…?

4. Pharmacokinetic Process: • Absorption • Distribution • Metabolism • Excretion Basic principles of pharmacology includes…

5. Medication management help patients by: • Curing disease or infection, relieving symptoms such as pain or nausea • Can also have the reverse effect: • In terms of: • Allergic reaction • Overdose • Adverse reaction • Administering wrong medication Patient safety is paramount!

6. Medications are distributed throughout the body by the blood and other fluids of distribution • Once they (the med) arrives at it’s proper site of action, they act by binding to receptors, usually located on the outer membrane of cells or enzymes located within the cell • Receptors are like biological “light switches” which turn on and off when stimulated by a drug which binds to the receptor and activates it Receptors – function?

7. Narcotics (Opioids) – like Morphine bind to receptors in the brain that sense pain and decrease the intensity of that perception • Antiplatelets (ASA); NSAIDs (Advil) or Antipyretics (Tylenol) bind to an enzyme located in the cells outside the brain close to where the pain is localized (e.g., hand, foot, low back, BUT NOT IN THE BRAIN) – thereby decreasing the formation of biologically-active substances known as prostaglandins, which cause pain and inflammation Receptors

8. Food for thought! • In some instances – a drug’s “site of action” or “receptor” may actually be something that resides within the body – but is not anatomically part of the body – • i.e., Tums – the site of action is the acid in the stomach that is chemically neutralized • However, if you take an OTC (Tagamet, Pepcid) that INHIBITS stomach acid production – instead of neutralization of acid, these compounds BIND to and INHIBIT receptors in the stomach wall responsible for producing acid! Receptors

9. Antibiotic therapy is another example of a drug that binds to a receptor that is not part of your body. Abx bind to portions of the bacterium that is living in the body which is causing illness. • Most Abx inhibit an enzyme inside the bacteria that causes the bacteria to either stop reproducing or to die from inhibition of a vital biochemical process Receptors – another example

10. As medical science has learned more about how drugs at, pharmacologists have discovered that the body is full of different types of receptors that respond to many different types of drugs. Some receptors are very selective and specific, while others lack such specificity and respond to several different types of drug molecules Pharmacologist discoveries

11. To date, receptors have been identified for the following common drugs, or neurotransmitters found in the body: • Narcotics (opioids) – Morphine • Benzodiazepines(Valium, Xanax) • Acetylcholine (nicotinic and muscarinic cholinergic receptors) found in the parasympathetic system (resting/digesting) • Dopamine, serotonin (sympathetic system) • Epinephrine (adrenalin) and NE (alpha and beta receptors) – found in the sympathetic system (fight/flight) of the CNS and many others…. Receptors – common drugs

12. Neurotransmitters are chemicals released from the END of ONE NEURON (nerve cell) which diffuse across the space between neurons called the synaptic cleft and stimulate an adjacent neuron to signal the transmission of information…. Neurotransmitters

13. Pharmacokinetics – what is it? – a branch of pharmacology which deals with determining the movement (kinetics) of drugs into and out of the body Pharmacokinetics

14. Absorption • Distribution • Metabolism • Excretion Four scientific or pharmacokinetic processes…..

15. Is the process by which a drug is made available to the fluids of distribution of the body (e.g., blood, plasma, serum, aqueous humor, lymph, etc.). • In the fasting state, most orally-administered drugs (PO) reach maximum or “peak” blood concentration within one to two hours • IV is the most rapid route of administration, then… • Intra-nasal • Inhalation • SL • IM • SC or SQ (in the above order) – route of administration…. Absorption

16. Dependent on (PO drugs) – and the subsequent appearance of the drug in the blood on the following factors: • Rate of disintegration and dissolution of the pill or capsule in the stomach or GI tract • Solubility of the drug (the more soluble, the faster absorption rate) • The molecular charge of the drug molecule (charged substances are soluble, but don’t pass through lipid (fat) soluble biologic membranes well) • Aqueous (water) solubility vs. lipid (fat) solubility • The presence or absence of food in the stomach (food delays the absorption of some drugs and enhances the absorption of others) Rate of Absorption -

17. The presence of any concomitant medication(s) that can interfere with GI motility (e.g., Reglan increase GI motility, Aluminum antacids slow motility, atropine or scopolamine used for ulcers or nausea also slow GI motility (anticholinergic) keeping some drugs in the stomach longer – slowing absorption rate; on the flip side: • Tagamet, Zantac and Prilosec (Pepcid-AC) DECREASE gastric acid production thereby INCREASING the rate of gastric emptying and increasing the rate of absorption.. Rate of Absorption – key factors

18. Once the drug has been absorbed from the stomach and/or intestines (GI tract) into the blood, it is circulated to some degree to all areas of the body to which there is blood flow…this process is distribution (the choo-choo so to speak) • Organs with high blood flow (brain, heart, liver, etc.) are the first to accumulate drugs, while connective tissue and lesser-perfused organs are last… Distribution

19. The pattern of distribution of drug molecules by different tissues after the chemical enters the circulatory system varies. Why? Because of differences in pH, lipid content, cell membrane function and other individual tissue factors, most drugs are NOT equally distributed in all parts of the body • E.g., ASA acidity influences a distribution patter that is different from that of an alkaline product such as amphetamine Distribution effects

20. Is the transformation of the drug molecule into a chemically related substance that is more easily excreted from the body (also know as: biotransformation, or detoxification) • Drug metabolism is the process by which the body breaks down and converts medication into active chemical substances. • Drugs can interact with other drugs, food and beverages. Interactions can lessen or magnify the desired therapeutic effect of a drug, or may cause unwanted or unexpected side effects Metabolism

21. The primary site of drug metabolism is the liver…plays a major role in digestion, detoxification, and elimination of substances from the body (ponder of this statement for moment…consider disease processes such as ES liver disease – what do you need to consider when administering drugs that are metabolized in the liver)? Metabolism – primary site

22. Enzymes in the liver are responsible for chemically changing drug components into substances known as metabolites • Metabolites are then bound to other substances for excretion through the lungs, or bodily fluids such as saliva, sweat, breast milk and urine, or through reabsorption by the intestines Metabolism

23. Can vary from individual to individual – and drug dosages that work quickly and effectively in one individual may not work well for another • Factors such as genetic disposition, environment, nutrition and age can influence drug metabolism • Infants and elderly patients may have a reduced capacity to metabolize certain drugs and can be at risk for drug toxicity Metabolic Rate

24. Therapeutic agents like antibiotics and drugs used for the treatment of high blood pressure, epilepsy (phenobarbital, Dilantin) pain (morphine, codeine), anxiety (valium Xanax) are also metabolized to chemically-related compounds called metabolites which are excreted in the urine… Metabolism

25. Diuretics (such as HCTZ) can reduce serum K+ and Na+ electrolyte levels when taken with digoxin and lithium respectively • MAOIs antidepressants can cause convulsions and other serious side effects when used with tricyclic antidepressants (nortriptyline), SSRIs or sympathomimetic drugs (amphetamines) • Antibiotics may reduce the efficiency or oral contraceptives Drugs that commonly interact with other meds:

26. Medications containing metals, such as antacids with aluminum additives and iron supplements can reduce the absorption of tetracycline's and fluoroquinolones • Drugs that inhibit liver enzyme function – thereby slowing metabolism include; ciprofloxacin, erythromycin, fluoxetine, paroxetine and ritonavir. The therapeutic effect of other medications taken with these drugs may be amplified – Coumadin should be used with GREAT caution in patients taking these drugs! Drugs that commonly interact with other meds:

27. Grapefruit juice inhibits metabolism of many meds; including: cyclosporines, felodipine, nifedipine, triazolam and midazolam (to name a few) • Foods and beverages with tyramines (red wine, malted beers, smoked foods, dried fruits and aged cheeses) can cause severe and dangerous elevation in blood pressure when taken with MAOI inhibitors (antidepressants – emsam; marplan; nardil; parnate) Foods and beverages / drug interactions

28. Dairy products (milk, cream) and products containing calcium can prevent the absorption of antibiotics such as tetracycline, doxycycline, and ciprofloxacin • Whole milk with Vitamin D can cause milk-alkali syndrome in patients taking aluminum hydroxide antacids • Caffeinated beverages can influence drug metabolism • Alcohol is a CNS depressant – should not be combined with other CNS depressants (antipsychotics, antihistamines) Foods and beverages / drug interactions

29. Is the process by which a drug is eliminated from the body – by various organs such as the kidney and lungs and found in many biological fluids like: bile, sweat, hair, breast milk, or tears. However, the most common is the urine (excretion of drug) • In order to determine the rate of excretion of any drug from the blood, one must first be certain that the entire drug in the patient’s GI tract has been absorbed (consider GI patients who’s absorption rate is impaired via their disease process…) Excretion

30. The amount of time required to eliminate half of the drug from the body is called the half-life • Generally, it takes six half-lives to rid the body of 98% of drug and 10 half-lives to completely eliminate the drug from the body • Using these mathematical relationships allows pharmacologists to determine how often a therapeutic drug should be administered to a patient or toxicologist to determine a time interval within which one would test positive for drugs of abuse Excretion

31. A medication will have a generic name and one or more trade names – the generic name usually signifies the medication's chemical derivation. The trade name is a name chosen by the pharmaceutical company for purposes of marketing. • Trade names usually begin with a capital letter and followed by a trademark • Generic names generally begin with a lower case letter Drug Nomenclature

32. Examples

33. Drugs are classified into different groups according to their chemical characteristics, structure and how they are used to treat specific diseases • Example: Controlled versus Non-controlled; Non-controlled med is not considered to be a depressant or a stimulant and is not considered addictive or with a potential for abuse (OTCs or prescription drug) Drug Classifications

34. Are divided into five schedules based on their potential for abuse and physical and psychological dependence Controlled Meds

35. Schedule I: drugs that currently do not have accepted medical use, have a high potential for abuse, and lack accepted safety measures for use (LSD, peyote, heroin) • Schedule II: drugs that have medical use and a high potential for abuse; may cause severe dependence (morphine, secobarbital, amphetamines (Ritalin), methadone) Controlled meds

36. Schedule III: drugs used in medical practice with less potential for abuse than Schedule II drugs; may cause moderate to low physical dependence or high-psychological dependence (T3s – Tylenol with codeine; stimulants, depressants, other classes – ketamine is another example) • Schedule IV: drugs that have medical use and lower abuse potential than CIII drugs; tend to cause limited physical or psychological dependence (diazepam) • Schedule V: drugs that have medical use and lower potential for abuse than CIV drugs – (cough syrups containing Codeine) Controlled Meds

37. Enable us to readily identify the similarities and differences among a large number of medications; one of the best ways to master pharmacology is to become familiar with medication classifications….let’s review some…. Drug Classifications

38. Alpha-Adrenergic Blockers

39. Antacids

40. Antianginals

41. Anticholinergics

42. Anticoagulants

43. Anticonvulsants

44. Antidepressants

45. Anti-Diabetic Meds

46. Antidiarrheal

47. Antidysrhythmics

48. Antifungals

49. Antihistamines

50. Antihypertensives