GPAT flashcards

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

Absolute bioavailability

Fraction of an administered dose reaching systemic circulation intact, calculated as (AUC oral × dose IV) divided by (AUC IV × dose oral); intravenous reference defines F equal to 1.

Higuchi release model

Describes drug release from a matrix as cumulative amount proportional to the square root of time, Q equals kH times t to the power 0.5, indicating diffusion-controlled release.

HLB value

Hydrophilic-lipophilic balance number from 0 to 20; values 3 to 6 favor water-in-oil emulsions, 8 to 18 favor oil-in-water emulsions, and 15 to 18 indicate solubilizing agents.

Carr's index

Flowability measure calculated as tapped density minus bulk density, divided by tapped density, times 100; below 15 percent indicates excellent flow and above 25 percent poor flow.

F0 value

Equivalent moist-heat sterilization time in minutes at 121 degrees Celsius for a microorganism with z value of 10 degrees; a sterility assurance level of 10 to the minus 6 is targeted.

Henderson-Hasselbalch equation

Relates pH to pKa and the ratio of ionized to unionized drug: pH equals pKa plus log of conjugate base over acid; used to predict absorption across membranes.

Bioisosterism

Replacement of a functional group by another of similar size, shape, or electronic properties, such as hydroxyl by amino, to retain activity while modifying metabolism or solubility.

Lipinski rule of five

Drug-likeness guideline for oral absorption: molecular weight at most 500, logP at most 5, hydrogen-bond donors at most 5, and hydrogen-bond acceptors at most 10.

Prodrug

Pharmacologically inactive derivative converted in the body to active drug; ester prodrugs of carboxylic acids improve oral absorption by masking charge until esterase hydrolysis.

Michaelis-Menten constant

Km is the substrate concentration at which reaction velocity is half of Vmax; low Km indicates high enzyme affinity and the Lineweaver-Burk slope equals Km divided by Vmax.

Therapeutic index

Ratio of toxic dose to effective dose in a population, commonly TD50 divided by ED50; a narrow index, as with digoxin, warfarin, and lithium, mandates therapeutic drug monitoring.

Elimination half-life

Time for plasma concentration to fall by half during first-order elimination, equal to 0.693 times volume of distribution divided by clearance; steady state is reached in four to five half-lives.

Loading dose

Initial dose used to reach target plasma concentration rapidly, calculated as volume of distribution times target concentration divided by bioavailability; maintenance dosing follows clearance.

Competitive antagonism

Reversible antagonist binding the same site as agonist, increasing apparent Kd and shifting the dose-response curve right without reducing maximal effect; surmountable by higher agonist concentration.

Aminoglycoside mechanism

These bactericidal antibiotics bind the bacterial 30S ribosomal subunit, causing misreading of mRNA and abnormal proteins; nephrotoxicity and ototoxicity require monitoring of levels.

Cardiac glycosides

Plant-derived steroid glycosides such as digoxin from Digitalis species; the aglycone determines activity by inhibiting sodium-potassium ATPase, while sugars modify solubility and potency.

Tannins

Polyphenolic plant constituents that precipitate proteins and are detected by ferric chloride giving blue-black color; used as astringents and in leather processing.

Volatile oils

Steam-distillable aromatic plant secretions; examples include eugenol from clove, menthol from peppermint, cineole from eucalyptus, and cinnamaldehyde from cinnamon.

Alkaloids

Nitrogen-containing basic plant compounds, often pharmacologically potent; examples include morphine from Papaver somniferum, quinine from Cinchona, and atropine from Atropa belladonna.

Beer-Lambert law

Absorbance equals molar absorptivity times path length times concentration; absorbance also equals log of incident over transmitted intensity, and is linear with concentration for dilute solutions.

HPLC resolution

Separation between two peaks calculated as twice the difference in retention times divided by the sum of their baseline widths; a value of at least 1.5 indicates baseline separation.

Karl Fischer titration

Specific method for water content using iodine, sulfur dioxide, and a base in methanol; suitable for hygroscopic active pharmaceutical ingredients and moisture-sensitive formulations.

Capacity factor

Retention factor k prime equals retention time minus void time, divided by void time; optimum values are roughly 1 to 10 for good chromatographic separation.

ICH Q2 validation

Analytical validation parameters include accuracy, precision, specificity, detection and quantitation limits, linearity, range, and robustness; these must be documented for regulatory submissions.

Competitive inhibition kinetics

Inhibitor binds the active site reversibly, raising apparent Km while Vmax stays unchanged; effect is overcome by increasing substrate concentration, unlike noncompetitive inhibition.

Cockcroft-Gault equation

Estimates creatinine clearance as (140 minus age) times weight divided by 72 times serum creatinine, multiplied by 0.85 for females; used for renal dose adjustment.

Pellagra

Niacin deficiency producing dermatitis, diarrhoea, and dementia; tryptophan is a precursor, and maize-based diets without niacin fortification predispose to the condition.

HbA1c

Glycated haemoglobin reflecting average glycaemia over the preceding two to three months; used to diagnose and monitor diabetes and to guide therapy adjustment.

Schedule H drugs

Prescription-only medicines under Indian drug law requiring a registered medical practitioner's prescription and a label warning that sale without prescription is an offence.

Schedule M

Part of Indian drug rules specifying Good Manufacturing Practices for premises, plant, equipment, and quality control; compliance is mandatory for licensed manufacturers.

Economic order quantity

Inventory model minimizing total ordering and holding cost, calculated as the square root of twice annual demand times ordering cost divided by holding cost per unit.

ABC analysis

Inventory classification by annual consumption value: A items are high-value and tightly controlled, B moderately controlled, and C low-value items ordered in bulk.