ACVCP flashcards

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

Bioavailability (F)

The fraction of an administered dose reaching systemic circulation intact; IV gives F = 1.0, and extravascular routes yield values below 1.0 due to incomplete absorption or first-pass metabolism.

Volume of distribution

The apparent volume relating total body drug amount to plasma concentration (Vd = Dose/C0); a large value indicates extensive distribution into tissues rather than plasma.

Clearance

The volume of plasma cleared of drug per unit time, calculated as CL = (Dose × F)/AUC; it determines the maintenance dose rate needed to sustain a target concentration.

Half-life

The time for plasma drug concentration to fall by half, calculated as t½ = 0.693 × Vd / CL; roughly four to five half-lives are needed to reach steady state.

First-order kinetics

Elimination in which a constant fraction of drug is removed per unit time, so the half-life is constant and independent of dose or concentration.

Zero-order kinetics

Saturation elimination in which a constant amount of drug is removed per unit time regardless of concentration; small dose increases can cause disproportionate, potentially toxic accumulation.

Ion trapping

The accumulation of a weak base in an acidic compartment (or weak acid in a basic one) because the ionized form cannot cross membranes; used clinically by alkalinizing urine to enhance elimination.

Cytochrome P450

The superfamily of hepatic phase I oxidative enzymes responsible for metabolizing most veterinary drugs; activity varies by species and can be induced or inhibited by co-administered agents.

Glucuronidation

A phase II conjugation reaction transferring glucuronic acid to drugs to increase water solubility for excretion; cats have limited capacity, prolonging elimination of many compounds.

P-glycoprotein

An efflux transporter at the blood-brain barrier and intestinal epithelium that pumps drugs out of cells; deficiency (MDR1 mutation) permits CNS toxicity from ivermectin and similar agents.

Therapeutic index

The ratio of the toxic dose to the effective dose; a narrow index means small dose changes risk toxicity, warranting therapeutic drug monitoring.

Loading dose formula

The initial dose needed to rapidly reach a target concentration, calculated as (Vd × target concentration)/bioavailability; it fills the volume of distribution without waiting for steady state.

Protein binding effects

Only unbound drug is pharmacologically active and filterable; high protein binding confines drug to plasma, and hypoalbuminemia raises free fraction, increasing effect and toxicity risk.

Prodrug activation

An inactive parent compound converted enzymatically to an active metabolite; examples include ester prodrugs and codeine's conversion to morphine via CYP enzymes.

COX-1 versus COX-2

COX-1 is constitutively expressed and supports gastric mucosal protection and renal perfusion, while COX-2 is largely induced during inflammation; selectivity affects adverse-effect profile.

Aminoglycoside killing pattern

Aminoglycosides kill bacteria in a concentration-dependent manner with a prolonged post-antibiotic effect, supporting once-daily dosing that limits renal cortical accumulation.

Beta-lactam time dependence

Beta-lactam efficacy depends on the duration that free drug exceeds the minimum inhibitory concentration, favoring frequent dosing or prolonged infusion.

Fluoroquinolone mechanism

Bactericidal agents inhibiting bacterial DNA gyrase and topoisomerase IV, blocking DNA replication; they are concentration-dependent and should be reserved for susceptible infections.

Enrofloxacin in cats

High doses of enrofloxacin can cause acute retinal degeneration and blindness in cats, so dose ceilings are observed and alternatives are preferred for feline patients.

Glucocorticoid tapering

Prolonged glucocorticoid use suppresses the hypothalamic-pituitary-adrenal axis; abrupt withdrawal risks adrenal crisis, so doses are reduced gradually to allow axis recovery.

Phenobarbital monitoring

Serum trough concentrations are checked to keep levels in the therapeutic range (about 15–45 µg/mL in dogs) while monitoring for sedation and hepatotoxicity with liver enzyme testing.

Potassium bromide use

An adjunct antiepileptic in dogs with a long half-life that allows once-daily dosing; it is avoided in cats and in patients with renal impairment due to bromide accumulation.

Levothyroxine monitoring

For canine hypothyroidism, dose is adjusted by measuring T4 several hours after the pill (roughly 4–6 hours) to confirm adequate post-pill concentration and clinical response.

Methimazole therapy

An antithyroid drug blocking thyroid hormone synthesis, used for feline hyperthyroidism; it can cause facial pruritus and blood dyscrasias requiring monitoring.

Insulin in diabetic cats

Cats often achieve diabetic remission with early insulin therapy and tight glycemic control, whereas dogs typically require lifelong insulin replacement.

Antimicrobial stewardship

Practice of using culture and susceptibility data to select the narrowest effective antimicrobial at appropriate dose and duration, reducing resistance emergence and preserving drug efficacy.

Digoxin therapeutic monitoring

Digoxin has a narrow therapeutic index; serum levels and electrolytes are monitored because hypokalemia and renal impairment increase the risk of toxicity and arrhythmias.

Antiemetic receptor targets

Vomiting is controlled by blocking receptors such as dopamine (metoclopramide), serotonin 5-HT3 (ondansetron), and NK1 (maropitant), selected by the underlying cause.

Gastroprotectant use

Proton pump inhibitors and H2 blockers reduce gastric acid secretion for ulcer management; sucralfate forms a protective barrier but can impair absorption of co-administered drugs.

Diuretic classes

Loop diuretics (furosemide) inhibit the Na-K-2Cl cotransporter in the thick ascending limb, producing potent diuresis; monitoring electrolytes and renal values is required.

Chemotherapy dose calculation

Cytotoxic drugs are dosed by body surface area (mg/m²) rather than weight alone, and doses are reduced for myelosuppression or organ dysfunction to limit toxicity.

Antiparasitic macrocyclic lactones

Ivermectin and related compounds act on glutamate-gated chloride channels; in MDR1-mutant dogs, CNS accumulation causes ataxia, tremors, and coma at routine doses.