Ch. 1&2: Essentials of Patho/Pharm

Etiology

Cause/origin of a disease

Risk factor

Any trait, behavior, or environment that increases the likelihood of contracting a disease.

Pathogenesis

Beginning + development of disease

Pathophysiology

Functional changes caused by a disease

Signs

objective/measurable or observable; e.g. fever, rash, cough, edema

Symptoms

subjective/unmeasurable (only felt by patient); e.g. pain, nausea, fatigue

Diagnosis

Identifying a disease by analyzing signs, symptoms, lab tests, etc.

Prognosis

Estimated/likely outcome of a disease

Primordial prevention

First level of prevention: prevent the development of risk factors; e.g., building clean water systems to prevent the risk of contaminated water that can spread certain infections.

Primary prevention

Second level of prevention: prevent disease by reducing risk factors; e.g., exercising to reduce the risk of obesity.

Secondary prevention

Third level of prevention: Detecting disease through early screening; e.g., routine mammogram screenings for early breast cancer detection.

Tertiary prevention

Fourth level of prevention: Disease is present; the focus shifts to reducing complications and slowing disease progression.

Chemical drug name

Describes molecular structure; e.g., Tylenol = N-(4-hydroxyphenyl)acetamide

Generic drug name

Official non-proprietary name; e.g., Tylenol = acetaminophen

Drug trade name

manufacturer’s proprietary name; e.g., Tylenol

Acute therapy

Immediate treatment to prevent deterioration

Maintenance therapy

ongoing control of a chronic condition

Supplemental therapy

Providing what the body lacks; e.g., IV Calcium gluconate for a patient with hypocalcemia.

Palliative therapy

Symptom relief/comfort; e.g., Morphine to relieve severe pain from a left hip fracture.

Supportive therapy

Maintains function during recovery

Prophylactic therapy

Prevents illness or complications

Empiric therapy

Treats likely cause before actual diagnosis

Pharmacokinetics

What the body does to a drug

Bioavailability

The extent of drug absorption; Many oral drugs have a bioavailability of <100%. IV Drugs have 100% bioavailability

First-pass effect

Decreases the bioavailability of the drug to <100%. Occurs when a drug is metabolized before reaching systemic circulation. High first-pass metabolism decreases bioavailability.

Pharmacokinetics: Absorption

How do we take the drug?; Bioavailability, first-pass effect, routes of administration, etc.

Pharmacokinetics: Distribution

How does the drug move through the body?; A drug bound to a protein continues to circulate. Free/unbound drug passes through blood vessels to tissues, where a drug-receptor-interaction occurs to carry out the desired action of the drug.

Protein binding (distrubution)

Drugs with high protein binding stay bound to protein in the blood vessels longer, thus having a longer half-life. Drugs with low protein binding move freely into body tissues and work more quickly.

Half-life

Time required for half (50%) of a given drug to be removed from the body.

Onset

Time required for a drug to elicit a therapeutic effect.

Peak

Time required for a drug to reach maximum therapeutic effect.

Duration

Length of time (without redose) a drug gives a therapeutic effect.

Toxicity

Occurs when the peak blood level is too high.

Therapeutic window

Minimum-maximum dose range of a drug that can be administered without triggering adverse effects or toxicity.

Blood levels below the therapeutic range

Drug is likely ineffective

Blood levels within therapeutic range

Drug takes desired effect w/ minimal risk

Blood levels above therapeutic range

Increases risk for toxicity

Pharmacokinetics: Metabolism

How does the body process the drug? Liver is the major organ for drug metabolism; Cytochrome P450 Enzyme System in the liver captains much of drug metabolism.

Lipid soluble drugs

Very difficult to be excreted from the body; The liver metabolizes them into more water-soluble metabolites, so the drug comes out when we void/defecate.

Cytochrome P450 Enzyme System

Family of enzymes mainly in the liver that metabolize many drugs. Can be inhibited (drug levels↑ = ↑risk of toxicity) or induced (drug levels↓ = ↓therapeutic effect).

Enzyme induction

Speeds up drug metabolism; Increases activity of metabolizing enzymes, and decreases the blood level and effect of the drug.

Enzyme inhibition

Slows down drug metabolism; decreases activity of metabolizing enzymes, and increases blood levels and effect of drug. Also increases risk for adverse effect/toxicity.

Pharmacokinetics: Excretion

How do we get rid of the drug?; The kidneys are the primary organs for excretion. Excretion will not occur without the other 3 principles happening first.

Pharmacodynamics: Mechanism of action

What a drug does to the body; the mechanism of action is the way the drug induces its effect (agonists, partial agonists, antagonists).

Agonists

Enhance the action of a drug within the body

Partial agonists

Promote binding to the receptor site and produce a delayed response.

Antagonists

Block or reduce the action of a drug in the body.

Drug tolerance

Decreased response to repeated drug doses (e.g., in myself, caffeine).

Physical dependence

The physical need for a drug to avoid physical withdrawal symptoms.

Psychologic dependence

“addiction”; obsessive desire for the effects of a drug.

Fastest oral route of administration

Oral disintegration

Slowest oral route of administration

Enteric coated tablets

Oral preparation route of administration (fastest to slowest)

oral disintegration, liquids/syrups, suspension solutions, powders, capsules, tablets, coated tablets, enteric-coated tablets

Parenteral route of administration

Medication delivered through skin, tissue, muscle, veins, or cavity. IV is by far the most rapid delivery; delivers drug directly into circulation.

Topical route of administration

Medication absorbed through the skin; e.g., ointments, creams, inhalers, nasal sprays, powders

Therapeutic class of drug

Based on the clinical purpose/disease/symptoms it treats. Think: “What problem is this drug treating?” (e.g., antibiotics, antidepressants)

Pharmacologic class of drug

Based on the mechanism of action/how it works in the body. Think: “How does this drug work in the body?” (e.g., beta-blocker, ACE Inhibitor)

Side effects

typically mild and tolerable (e.g., nausea, weight gain, fatigue)

Adverse effects

Moderate-to-severe effects; often lead to dose reduction or discontinuation. (e.g., severe bleeding when taking an anticoagulant with penicillin).