TT Pharmacy Registration Exam cheat sheet

Bioavailability F = (AUC_oral / AUC_IV) × (Dose_IV / Dose_oral); absolute F uses IV reference, relative F uses another non-IV product.

Noyes–Whitney dissolution rate dC/dt = (D·A/h)·(Cs − C): rate rises with surface area A, diffusion coefficient D, and saturation solubility Cs.

First-order elimination half-life t½ = 0.693 / k; after n half-lives approximately 1 − (0.5)^n of steady state is reached (≈97% at 5 half-lives).

Loading dose = (Vd × target concentration) / F; maintenance dose rate = (CL × target concentration) / F.

Higuchi square-root release: amount released ∝ √t; zero-order release gives constant amount per unit time (used in osmotic and reservoir systems).

Stokes' law sedimentation velocity v = d²(ρp − ρf)g / 18η: smaller particles and higher viscosity slow sedimentation and improve suspension stability.

Tablet hardness is measured in kp or N (crushing force); friability is % weight loss after 100 rotations at 25 rpm, generally ≤1% acceptable.

Biopharmaceutics Classification System: Class I high solubility/high permeability, II low solubility/high permeability, III high solubility/low permeability, IV low/low.

Sterilization by moist heat: 121 °C at 15 psi for 15–20 min achieves 12-log reduction of Geobacillus stearothermophilus spores (F0 ≥ 12 min).

Competitive antagonist shifts the agonist dose–response curve right without lowering Emax; non-competitive antagonism reduces Emax.

Therapeutic index = TD50 / ED50; a lower value indicates a narrower margin of safety.

Receptor families: ligand-gated ion channels (fastest, ms), G-protein coupled (seconds), kinase-linked, and nuclear receptors (slowest, hours, gene transcription).

Zero-order kinetics (e.g., phenytoin, ethanol, high-dose salicylates) give constant amount eliminated per time; small dose increases can cause disproportionate rises in plasma level.

First-pass hepatic metabolism reduces oral bioavailability; routes bypassing it include IV, sublingual, transdermal, and rectal (partial).

Warfarin inhibits vitamin K epoxide reductase; heparin potentiates antithrombin III - monitor INR and aPTT respectively.

Beta-1 selective blockers (e.g., atenolol, bisoprolol) reduce cardiac rate and renin release with less bronchospasm than non-selective agents.

Cholinergic crisis vs. myasthenic crisis: excess muscarinic signs (SLUDGE: salivation, lacrimation, urination, defecation, GI upset, emesis) suggest cholinergic excess.

Lipinski's Rule of Five: MW ≤ 500, logP ≤ 5, H-bond donors ≤ 5, H-bond acceptors ≤ 10; violation of ≥2 predicts poor oral absorption.

Stereochemistry: enantiomers differ in three-dimensional arrangement; only the (S)-enantiomer of ibuprofen is pharmacologically active (eutomer) - racemic mixtures may have differing potency.

Bioisosteres replace a group with similar physicochemical properties (e.g., –OH/–NH2, –Cl/–CH3, –COOH/tetrazole) to preserve activity while altering metabolism or pKa.

Prodrugs are inactive derivatives requiring biotransformation (e.g., enalapril → enalaprilat, codeine → morphine via CYP2D6).

Phase I reactions (oxidation, reduction, hydrolysis via CYP450) introduce or unmask polar groups; Phase II (glucuronidation, sulfation, acetylation) conjugate to increase water solubility.

pKa and ionization: for a weak acid, % ionized = 100/(1 + 10^(pKa − pH)); ionized species are less lipid-permeable.

Structure–activity relationship: small changes in alkyl chain length or ring substitution can dramatically alter receptor affinity and metabolic stability.

Enzyme inhibitors: reversible competitive inhibitors raise apparent Km; irreversible inhibitors (e.g., aspirin acetylating COX) permanently inactivate enzyme until new enzyme is synthesized.

Pharmaceutical care process: assessment (collect data), care plan (identify and prioritize problems), implementation, and follow-up/monitoring.

SOAP note format: Subjective, Objective, Assessment, Plan - used to document clinical encounters.

Drug therapy problems categories: indication, effectiveness, safety, and adherence; each requires a specific intervention.

Therapeutic drug monitoring is indicated for drugs with narrow therapeutic index and good correlation between plasma level and effect (e.g., digoxin, lithium, vancomycin, phenytoin).

Vancomycin AUC/MIC target for serious MRSA infection is 400–600 mg·h/L (or trough 15–20 mg/L for conventional monitoring).

Medication reconciliation: obtain best possible medication history, compare to current orders, resolve discrepancies, and communicate at transitions of care.

Patient counseling uses teach-back to confirm understanding; include drug name, purpose, dose, timing, duration, and key adverse effects.

Adverse drug reaction causality tools include the Naranjo probability scale (definite, probable, possible, doubtful).

Alligation: ratio of parts = (higher % − desired %) : (desired % − lower %) to combine two strengths into a target concentration.

Dilution formula C1V1 = C2V2 applies to concentration–volume problems; for percentage w/v, grams per 100 mL.

Creams and ointments: % w/w = (mass of solute / total mass) × 100; % w/v = (g / 100 mL) × 100.

Body surface area (Mosteller): BSA (m²) = √[(height cm × weight kg) / 3600]; pediatric doses may use mg/m².

Young's rule for pediatric dose: child dose = (age in years / (age + 12)) × adult dose; Clark's rule uses weight in lb / 150.

Drip rate (drops/min) = (volume mL × drop factor gtt/mL) / time in minutes; common drop factors: 15, 20, 60 gtt/mL.

Isotonicity: 0.9% w/v NaCl is isotonic; sodium chloride equivalent (E-value) method: NaCl equivalent = weight of drug × E.

Compounding: geometric dilution for potent powders; levigation for ointments; use calibrated equipment and document beyond-use dates.

Prescription requirements typically include prescriber name, license/registration number, patient name and address, drug name, strength, dosage form, quantity, directions, and date/signature.

Controlled substances are classified into schedules (e.g., Schedule I no accepted medical use; Schedule II high abuse potential with severe dependence) with stricter record-keeping and refill limits.

Refill limits: Schedule II generally no refills; Schedule III–IV limited refills (commonly up to 5 within 6 months) per jurisdiction.

Pharmacist ethical principles: beneficence, non-maleficence, autonomy, justice, veracity, and confidentiality (privacy of patient health information).

Generic substitution is generally permitted unless the prescriber indicates 'no substitution' or the patient refuses; bioequivalence standards apply.

Record retention for controlled substances commonly 2 years (varies by jurisdiction) and must be readily retrievable for inspection.

Duty to counsel and to report adverse drug reactions and dispensing errors; error reporting systems support quality improvement.

Scope of practice defines authorized activities; exceeding scope (e.g., prescribing without authority) is a regulatory violation.

Alkaloids are nitrogen-containing basic compounds (e.g., morphine from Papaver somniferum, quinine from Cinchona, caffeine from Coffea).

Glycosides: cardiac glycosides (digoxin from Digitalis lanata) act on Na+/K+-ATPase; cyanogenic glycosides release cyanide on hydrolysis.

Tannins are polyphenolic astringents that precipitate proteins; found in tea, oak gall, and used in wound healing.

Essential oils are volatile terpenoids (e.g., menthol from Mentha, eugenol from clove) obtained by steam distillation or expression.

Plant identification uses macroscopic (leaf shape, venation), microscopic (trichomes, stomata), and chemical (TLC, HPLC fingerprint) methods.

Standardization of herbal products requires marker compounds and validated assays to ensure batch-to-batch consistency.

Herb–drug interactions: St John's wort induces CYP3A4 (reduces efficacy of oral contraceptives and warfarin); ginkgo may increase bleeding risk.

Levels of prevention: primary (before disease, e.g., immunization), secondary (early detection, e.g., screening), tertiary (limiting disability/rehabilitation).

Incidence = new cases / population at risk per time; prevalence = all existing cases / total population at a point or period.

Relative risk (cohort) = incidence in exposed / incidence in unexposed; odds ratio approximates RR for rare diseases in case-control studies.

Sensitivity = TP/(TP+FN); specificity = TN/(TN+FP); positive predictive value depends on disease prevalence.

Herd immunity threshold ≈ 1 − 1/R0; higher R0 requires higher vaccination coverage to interrupt transmission.

Screening criteria: important health problem, accepted treatment, detectable early stage, suitable test, and cost-effective program.

Health promotion models include the Health Belief Model, Transtheoretical (stages of change), and socio-ecological model (individual to policy levels).

Inventory control: economic order quantity EOQ = √(2DS/H), where D = annual demand, S = ordering cost, H = holding cost per unit.

ABC analysis classifies stock by value (A = high-value, few items) to prioritize inventory control; VED classifies by criticality (vital, essential, desirable).

Cost-minimization analysis compares alternatives with equivalent outcomes; cost-effectiveness uses cost per health outcome (e.g., cost per QALY).

Incremental cost-effectiveness ratio (ICER) = (Cost_new − Cost_old) / (Effect_new − Effect_old); compare against willingness-to-pay threshold.

Budget impact analysis estimates financial consequences of adopting a new therapy over a defined time horizon for a payer.

Break-even point in units = fixed costs / (price per unit − variable cost per unit).

Pharmacoeconomic perspectives: societal, payer, provider, and patient - the chosen perspective determines which costs are included.