Pharm Aug 26 1st day of class

Drug definition: any molecule that changes body function at chemical/cellular levels.
Drugs and medications are used to prevent, treat, or diagnose health problems.
“Drug” and “medication” are used interchangeably by healthcare providers.
Coffee, nicotine, alcohol are examples of drugs by this definition.

Intrinsic (internal production) vs extrinsic (external administration) drugs.
Three names: chemical, generic, brand. Generic names are required for tests; brand names are common in practice.
Over-the-counter (OTC) vs prescription: OTC are generally weaker; prescriptions may require monitoring.
Herbal products are also drugs and can interact with other meds.

High-alert drugs (PINCH): Potassium, Insulin, Narcotics, Chemo agents, Heparin.
Many high-alert meds require a second nurse to verify calculations.
Labels and standards governed by agencies:
- USP sets compounding/labeling standards (not enforcement).
- FDA enforces USP standards for products and labeling.
- DEA regulates controlled substances.
Controlled substances are scheduled I–V based on abuse potential and medical use.
DEA numbers are required for prescribers of controlled substances.

Pharmacodynamics: what the drug does to the body; mechanism of action; indications; receptor interactions (agonists vs antagonists); target tissues; therapeutic effects; side effects vs adverse effects; black box warnings.
Pharmacokinetics: what the body does to the drug; absorption, distribution, metabolism, excretion (ADME); bioavailability; routes of administration; first-pass effect.
Minimum effective concentration (MEC): plasma level needed for therapeutic effect.
Peak vs trough: peaks = highest drug level; troughs = lowest drug level; used to assess toxicity and adequacy.
Steady state: when input equals clearance over time.

Route categories:
- Enteral: GI tract (oral, sublingual, etc.).
- Parenteral: injections (IM, SubQ, IV, intradermal).
- Percutaneous: skin/topical; mucous membranes (sublingual, intranasal, etc.).
- Inhalation: absorbed via lungs (often considered mucous membranes).
Bioavailability ( $F$ ): fraction of the dose reaching systemic circulation; IV = $F=1$ ; PO/other routes 0<F<1 due to first-pass effects.

Absorption and distribution determine onset and intensity of effect.
Metabolism (mainly liver; kidneys also involved) inactivates drugs; some meds hepatotoxic.
Excretion (primarily kidneys; also bile, lungs, sweat).
Organ function (liver, kidneys) affects dosing and risk of toxicity.

Dose timing and range aim for MEC without reaching toxic levels.
Half-life ( $t_{1/2}$ ): time for the drug amount to reduce by half.
Example: after each $t_{1/2}$ interval, amount remaining is multiplied by $rac{1}{2}$ .
- After $n$ half-lives: $D = D_0 \bigl( frac{1}{2}\bigr)^n$
- If $t_{1/2}=8$ h and dose 500 mg at 0 h, after 8 h → 250 mg; after 16 h → 125 mg.
Peaks and troughs: peak = highest level; trough = lowest level; used to assess safety and adequacy for toxic drugs.
Steady state: achieved when dosing rate = elimination rate.

Indication: reason to prescribe a drug.
Mechanism of action (MOA): how the drug produces its effect (receptor interactions, tissue targets).
Receptor concepts:
- Agonists: activate receptors to produce effect.
- Antagonists/Blockers: prevent receptor activation.
Side effects vs adverse effects:
- Side effects: non-therapeutic effects that may be tolerable.
- Adverse effects: harmful effects that may require stopping the drug.
Allergic reactions/anaphylaxis: life-threatening; require immediate medical care; often related to antibiotics.
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