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

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Pharmacology Basics Adapted from NurseCE4less.com for Ambercare Corporation Education Department, 2014 Slide 2 OBJECTIVES 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 Slide 3 DID YOU EVER WONDER? 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? Slide 4 Basic principles of pharmacology includes Pharmacokinetic Process: Absorption Distribution Metabolism Excretion Slide 5 Patient safety is paramount! 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 Slide 6 Receptors function? Medications are distributed throughout the body by the blood and other fluids of distribution Once they (the med) arrives at its 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 Slide 7 Receptors 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 Slide 8 Receptors Food for thought! In some instances a drugs 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! Slide 9 Receptors another example 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 Slide 10 Pharmacologist discoveries 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 Slide 11 Receptors common drugs 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. Slide 12 Neurotransmitters 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. Slide 13 Pharmacokinetics Pharmacokinetics what is it? a branch of pharmacology which deals with determining the movement (kinetics) of drugs into and out of the body Slide 14 Four scientific or pharmacokinetic processes.. Absorption Distribution Metabolism Excretion Slide 15 Absorption 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. Slide 16 Rate of Absorption - 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 dont 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) Slide 17 Rate of Absorption key factors 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.. Slide 18 Distribution 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 flowthis 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 Slide 19 Distribution effects 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 Slide 20 Metabolism 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 Slide 21 Metabolism primary site The primary site of drug metabolism is the liverplays a major role in digestion, detoxification, and elimination of substances from the body (ponder of this statement for momentconsider disease processes such as ES liver disease what do you need to consider when administering drugs that are metabolized in the liver)? Slide 22 Metabolism 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 Slide 23 Metabolic Rate 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 Slide 24 Metabolism 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 Slide 25 Drugs that commonly interact with other meds: 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 Slide 26 Drugs that commonly interact with other meds: 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! Slide 27 Foods and beverages / drug interactions 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) Sli