APC Written Assessment flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Volume of distribution

Apparent volume relating the amount of drug in the body to its plasma concentration (Vd = Dose/C0); large values indicate extensive distribution into tissues.

Drug clearance

Volume of plasma cleared of drug per unit time (CL = k × Vd); it determines the maintenance dose rate needed to sustain a target steady-state concentration.

First-order elimination half-life

Time for plasma concentration to halve during first-order elimination; t½ = 0.693/k and is independent of dose or concentration.

Zero-order kinetics

Elimination of a constant amount per unit time when pathways are saturated; concentration falls linearly and half-life increases as concentration rises, as with ethanol and phenytoin.

Oral bioavailability

Fraction of an administered dose reaching systemic circulation intact; F = (AUCoral/AUCiv) × (Doseiv/Doseoral) and is reduced by first-pass metabolism.

Henderson-Hasselbalch equation

pH = pKa + log([base]/[acid]); it predicts ionization of weak acids and bases, and ionized drug is generally less able to cross lipid membranes.

Prodrug

Inactive derivative converted in the body to the active drug, often to improve absorption or stability; for example, enalapril is hydrolyzed to enalaprilat.

Enteric coating

Polymer coating that resists gastric acid and dissolves at higher intestinal pH, protecting acid-labile drugs or the stomach; cellulose acetate phthalate is an example.

Michaelis-Menten kinetics

v = Vmax·C/(Km + C); at concentrations far below Km elimination is first-order, but near or above Km it becomes zero-order and saturable.

LogD

pH-dependent distribution coefficient covering ionized plus unionized drug partitioning into octanol; more predictive of membrane permeation than logP at physiological pH.

Higuchi release model

Drug release from a matrix system proportional to the square root of time; typical of diffusion-controlled sustained-release tablets rather than zero-order delivery.

Competitive antagonist

Binds reversibly at the agonist binding site, shifting the dose-response curve right without lowering maximal effect; more agonist can overcome the block.

Partial agonist

Produces a submaximal response even at full receptor occupancy; can behave as a functional antagonist when a full agonist is also present.

Therapeutic index

Ratio of toxic to effective dose (TD50/ED50); low values, as with digoxin, lithium, warfarin and phenytoin, demand careful monitoring.

Beta-2 receptor activation

Relaxes bronchial and vascular smooth muscle; nonselective beta blockers such as propranolol can therefore precipitate bronchospasm in patients with asthma.

ACE inhibitor mechanism

Blocks conversion of angiotensin I to angiotensin II and lowers aldosterone; bradykinin accumulates, causing cough, and hyperkalemia and angioedema may occur.

Warfarin mechanism

Inhibits vitamin K epoxide reductase, reducing functional factors II, VII, IX and X; the anticoagulant effect is delayed and monitored with the INR.

Heparin monitoring

Unfractionated heparin activates antithrombin and is monitored by the aPTT; protamine sulfate reverses its anticoagulant effect.

Aminoglycoside mechanism

Binds the bacterial 30S ribosomal subunit, causing misreading and bactericidal killing; activity is concentration-dependent, with nephrotoxicity and ototoxicity.

Loop diuretic target

Inhibits the Na-K-2Cl cotransporter in the thick ascending limb, producing powerful diuresis; hypokalemia, hypocalcemia and ototoxicity are possible.

Naloxone reversal

Competitive opioid receptor antagonist that rapidly reverses mu-opioid effects including respiratory depression; its short half-life may require repeat dosing or infusion.

CYP2D6 and codeine

Codeine is activated by CYP2D6 to morphine; poor metabolizers get little analgesia, while ultrarapid metabolizers risk opioid toxicity.

High-alert medications

Drugs carrying heightened risk of serious harm when misused, such as insulin, heparin, opioids and concentrated potassium; they require independent double-checks and standardized storage.

Error-prone abbreviation U

The abbreviation 'U' for units is easily misread as a zero or a four; write 'unit' in full to prevent tenfold dosing errors.

Schedule II refills

Under federal DEA rules Schedule II prescriptions cannot be refilled; multiple prescriptions may be issued with earliest-fill dates under specified conditions.

USP 797 ISO 5 area

The direct compounding area for sterile preparations must meet ISO Class 5 air quality and be located inside an ISO Class 7 buffer room.

USP 800 requirements

Sets containment requirements for hazardous drug handling, including negative-pressure rooms, closed system transfer devices and personal protective equipment.

MedWatch reporting

FDA program for voluntary and mandatory reporting of adverse drug events and serious product problems by healthcare professionals and consumers.

Medication reconciliation

Structured process of comparing a patient's medication list across care transitions to identify and resolve discrepancies, omissions, duplications and dosing errors.

Naranjo scale

Ten-item validated tool estimating the probability that an adverse drug reaction is caused by a drug, classifying it as definite, probable, possible or doubtful.

Teach-back method

Counseling technique in which the patient explains the instructions in their own words, confirming understanding and revealing gaps in counseling.

OBRA 90 counseling

US law requiring pharmacists to offer counseling and perform prospective drug utilization review for Medicaid outpatients; many states later extended it broadly.