Pharmacokinetics Study Notes PDF

Pharmaceutics is how different routes of medications influence the way a drug effects the body. You need to know the different forms medications can be dosed - **What did you learn from your reading about pharmacokinetics? What is it?** - It is a group of principles describing what hap...

Pharmaceutics is how different routes of medications influence the way a drug effects the body. You need to know the different forms medications can be dosed - **What did you learn from your reading about pharmacokinetics? What is it?** - It is a group of principles describing what happens to a drug from the moment it is consumed until the **parent drug** and all metabolites (molecules) are excreted/leave the body. - **What are the four principles or concepts that fall under pharmacokinetics?** (A-D-M-E) - What is Distribution? - How do drugs travel to the sites of action? - Free drug molecules are the only drug metabolites that are able to move outside of the vessels and to the action sites. They cannot be bound to any plasma proteins (which is usually albumin) because the proteins are too large to fit through the cell membranes for passage. Fig 2.4 is a visual of it. - If a drug is unbound or \"free\" it is in an active state - If a drug is bound then it is in an unactive state - Why would the RN need to take caution in individuals who have low plasma proteins such as albumin?   - Conditions that could cause this are extensive burns or malnourished states - What do you know about drug-drug interactions? - How could this affect the patient outcome? - Explain blood brain barrier - What is it? - Why is this important? - What is metabolism? - What does it do/what can it do to the drug? - What organ is most responsible for metabolism? - P-450 - What is it? - Enzyme that breaks down lipid soluble dugs - Responsible for the breakdown of the majority of medications - What is excretion? - What is the primary organ system responsible? - Kidneys - Excretion process contains the glomerular filtration, active tubular reabsorption, and active secretion - Explain the process of which the renal system uses to excrete a drug - What is half life? - The time required for 50% of a drug to be eliminated from the body - Onset of Action - Time required for a drug to start to have a therapeutic response - Duration of Action - Length of time the drug concentration is sufficient without more doses - Peak Level - Highest blood level - Trough Level - Lowest blood level - Therapeutic Drug Monitoring - Using the peak and trough levels to adequately and precisely verify drug exposure - What is pharmacodynamics? - It's the mechanisms of drug action in living tissues - Recap, we know that therapeutic effect = good - Mechanism of Action - How the drug interacts with the tissues at a cellular level - Interaction types - Receptor - When the drug molecule attaches to a reactive receptor site to accomplish the goal of the drug - Table 2.8 breaks down each of the five drug types and gives the action each type produces - Enzyme - When the drug molecule binds with the specific enzyme and either enhances or inhibits its function in the body (selective interaction) - Nonselective - Drugs that do not have specific interactions via receptor sites or enzymes but instead they target cell membrane to alter the metabolic processes of that cell (antibiotics or oncologics) - What is a contraindication? - Any pt condition that makes the use of a specific drug(s) dangerous for the pt - Types of Therapy - Acute: drug therapy used in an acute care setting to treat disease or sustain life (pressors or volume expanders) - Maintenance: drug therapy to chronically control the disease but will not cure it. (at home blood pressure or cholesterol meds) - Supplemental: gives the body what it is lacking to maintain function (insulin) - Palliative: makes the pt comfortable by treating symptoms of disease process (pain meds during cancer battle) - Supportive: used to keep optimal function of body while recovering (fluids to prevent dehydration r/t n/v/d) - Prophylactic: prevents illness - Empirical: drugs used before confirmation of illness based on the probability of condition (UTI antibiotics) - Monitoring - Adverse effect: undesirable effect that is a direct response to one or more meds; predictable - Therapeutic Index: the ratio between toxicity of a drug and therapeutic effect (Small index = greater chance for toxicity) - Tolerance: a decreasing response to repeated doses of med - Dependence: physiologic/psychologic need for a drug - Drug interactions: - Table 2.9 shows some of the food and drug interactions that may be had. We will look more into this in Ch 7 - Drug incompatibility: when 2 IV drugs are mixed, and it results in either deterioration of one or both drugs or the creations of a physical precipitate - **Always inspect IV bags for cloudiness or particulates before administration; contact the pharmacy and discard the IV bag** - Adverse Drug Reaction (ADR): any reaction to a drug that is unexpected/undesirable and occurs within the therapeutic range; **not to be confused with adverse effects (which is a predictable response)** - Medication errors: preventable situation where there is a compromise in the "Six Rights" of medication use; this is more common than adverse drug reactions - Allergic Reaction: when the immune system (immunoglobulins) sees the drug molecules as dangerous foreign bodies - Teratogenic effects: drugs that cause structural defects to babies in the womb - Carcinogenic effects: cancer-causing effects; called carcinogens - What is a dietary supplement? Herb? - FDA required info to be provided about the herb/diet supp. but did not require approval for it to be sold on the market - Education - Herbs and drug interactions are a big education point for patients - Table 7.3 is a good study reference when reviewing specific herbs and supplements - Cranberry: decreases elimination of renally excreted drugs - Garlic: Possible interference with decreased blood glucose therapy and warfarin - Gingko: increased bleeding risk with anticoagulants and antiplatelets - Grapefruit: decreased metabolism of some drugs (primarily those that are metabolized via P-450)l; increases the intensity/duration of caffeine effects - Kava: increases effects of barbiturates and ETOH; can cause liver toxicity - St. John's Wort: can lead to serotonin syndrome if taken with SSRIs; has a list of drug classes that it may interact with - Make sure pts receive as much information about: - safe use with herbal and OTC supplements - that herb/dietary supp are not FDA regulated - just cause herbs or dietary supp may be a natural substance, that does NOT mean they are safe during pregnancy - Patient-Centered Care Box pg 92 has great patient teachings to know and understand