Iran Pharmacy Ph.D. Entrance Exam cheat sheet

Bioavailability F = (AUC_oral / AUC_iv) × (Dose_iv / Dose_oral); absolute F compares to IV, relative F to a reference product.

Noyes–Whitney dissolution rate: dC/dt = (D·A/h)·(Cs − C), where A is surface area, h diffusion layer thickness, Cs saturation solubility; particle size reduction increases A and rate.

Henderson–Hasselbalch for weak acids: pH = pKa + log([A−]/[HA]); for weak bases: pH = pKa + log([B]/[BH+]). Absorption of a weak acid is favored at pH < pKa in unionized form.

BCS Class I high solubility/high permeability; Class II low solubility/high permeability (dissolution-rate limited); Class III high solubility/low permeability (permeability limited); Class IV low/low.

Zero-order release: amount released = k0·t; first-order: amount remaining = A0·e^(−kt); Higuchi matrix: Q = kH·t^(1/2); Korsmeyer–Peppas: Mt/M∞ = k·t^n, n ≈ 0.5 Fickian diffusion, n ≈ 1 Case-II relaxation.

Stokes' law sedimentation velocity v = d²(ρp − ρl)g/(18η); smaller diameter and higher viscosity lower v, guiding suspension and emulsion stability.

Tablet compaction: Heckel equation ln(1/1−D) = K·P + A yields mean yield pressure from slope; lower yield pressure indicates more plastic deformation.

Osmotic pump (OROS) delivers zero-order rate dM/dt = (A/h)·Lp·(Δπ − ΔP)·Cs; rate is independent of gastrointestinal pH and motility.

Stability Q10 rule: reaction rate roughly doubles per 10 °C rise; Arrhenius k = A·e^(−Ea/RT) predicts shelf life from accelerated data.

Receptor occupancy: [LR]/[R]total = [L]/([L] + Kd); Kd is the ligand concentration producing 50% occupancy.

Competitive antagonist shifts agonist log dose–response curve right with unchanged Emax; noncompetitive antagonist lowers Emax; partial agonist has lower intrinsic activity than full agonist.

Therapeutic index = TD50/ED50; a larger value indicates a wider margin of safety. Certain safety factor = LD1/ED99.

First-order elimination: t1/2 = 0.693·Vd/CL; steady-state concentration Css = (F·Dose)/(CL·τ).

Cytochrome P450 inducers (rifampin, carbamazepine, phenytoin, St John's wort) lower substrate levels; inhibitors (ketoconazole, ritonavir, grapefruit furanocoumarins) raise them.

Organophosphate toxicity: irreversible acetylcholinesterase inhibition → cholinergic crisis (SLUDGE); antidotes atropine (muscarinic) plus pralidoxime (reactivates enzyme before aging).

Acetaminophen overdose: NAPQI accumulation after glutathione depletion; N-acetylcysteine replenishes glutathione and is most effective within 8–10 h.

Warfarin: vitamin K antagonist inhibiting VKORC1; monitored by INR; major interactions with CYP2C9 inhibitors and drugs altering vitamin K or platelet function.

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

Veber rules: rotatable bonds ≤ 10 and polar surface area ≤ 140 Ų predict good oral bioavailability in rats.

Hansch equation: log(1/C) = k·logP + ρ·σ + k′; σ is the Hammett electronic constant, π is the hydrophobic substituent constant.

Bioisosteres: replace –OH with –NH2 or –F, –COOH with tetrazole, phenyl with thiophene; aim to retain activity while changing metabolism or pKa.

Prodrug design: ester prodrugs of carboxyl drugs (e.g., enalapril → enalaprilat) improve absorption; amide/ester hydrolysis by esterases releases active drug.

CYP2D6 poor metabolizers show reduced activation of codeine to morphine and reduced clearance of tricyclics; CYP2C19 poor metabolizers have reduced clopidogrel activation.

Michael acceptor warheads (acrylamide, vinyl sulfone) form covalent bonds with cysteine residues in kinases (e.g., EGFR T790M inhibitors); reactivity must be tuned to limit off-target toxicity.

Molecular descriptors: QED, ligand efficiency = ΔG/N heavy atoms, and LipE = pIC50 − logD are used to rank lead compounds.

Alkaloids: basic nitrogen heterocycles; extracted by acid–base partitioning; examples are morphine (phenanthrene), quinine (quinoline), atropine (tropane).

Cardiac glycosides (digoxin, digitoxin) have a steroid aglycone plus lactone; inhibit Na+/K+-ATPase; sugar moiety affects pharmacokinetics.

Flavonoids share a C6-C3-C6 skeleton; anthocyanins are flavylium cations; isoflavones (genistein) act as phytoestrogens.

Terpenoids follow the isoprene rule (C5 units); monoterpenes C10, sesquiterpenes C15, diterpenes C20; menthol is a monoterpene, taxol a diterpenoid.

Extraction methods: maceration (cold soak), percolation (continuous solvent flow), Soxhlet (reflux, exhaustive), supercritical CO2 (nonpolar, low temperature).

Thin-layer chromatography Rf = distance traveled by solute / distance traveled by solvent front; Rf depends on stationary phase polarity and solvent system.

Quality markers: marker compounds (e.g., ginsenoside Rb1 for ginseng, hypericin for St John's wort) are quantified by HPLC for standardization.

Toxic plant principles: ricin (Ricinus communis) inhibits ribosomal protein synthesis; coniine (Conium maculatum) is a nicotinic antagonist; digitalis glycosides cause bradycardia and hyperkalemia.

Beer–Lambert law: A = ε·b·c; absorbance is proportional to concentration at a given wavelength; deviations occur at high concentration or with polychromatic light.

HPLC resolution Rs = 2(tR2 − tR1)/(w1 + w2); baseline separation generally requires Rs ≥ 1.5.

Chromatographic figures of merit: retention factor k = (tR − t0)/t0; selectivity α = k2/k1; plate number N = 16(tR/w)²; plate height H = L/N.

Van Deemter equation H = A + B/u + C·u; optimum flow minimizes H; smaller particles reduce the A and C terms in UHPLC.

UV–Vis detectors operate at fixed or variable wavelength; photodiode array (PDA) records full spectra for peak purity assessment.

Mass spectrometry: ESI and APCI are common LC-MS interfaces; m/z = mass/charge; tandem MS (MRM) provides high selectivity for bioanalysis.

Validation parameters per ICH Q2(R1): accuracy, precision (repeatability, intermediate, reproducibility), specificity, linearity, range, LOD, LOQ, robustness.

LOD and LOQ from signal-to-noise: LOD ≈ 3:1, LOQ ≈ 10:1; from calibration SD: LOD = 3.3σ/S, LOQ = 10σ/S.

NMR chemical shift is referenced to TMS (0 ppm); integration is proportional to number of equivalent protons; coupling constant J is in Hz and independent of field strength.

Cockcroft–Gault creatinine clearance: CrCl (mL/min) = [(140 − age) × weight]/(72 × SCr), multiply by 0.85 for females; used for renal dose adjustment.

Vancomycin dosing: target AUC24/MIC 400–600 for serious MRSA infection; trough-only monitoring 15–20 mg/L is an alternative; adjust for renal function.

Aminoglycoside extended-interval dosing: once-daily high dose relies on concentration-dependent killing and post-antibiotic effect; monitor trough to avoid toxicity.

Heart failure quadruple therapy: ARNI/ACEi/ARB + evidence-based beta-blocker + MRA + SGLT2 inhibitor reduces mortality; diuretics for congestion.

Warfarin management: initiate 5 mg daily (lower in elderly or hepatic impairment); target INR 2–3 for most indications, 2.5–3.5 for mechanical mitral valves.

Asthma stepwise therapy: as-needed ICS-formoterol is preferred reliever; add LAMA or increase ICS before oral corticosteroids; biologics for severe eosinophilic asthma.

Diabetes: metformin first-line unless contraindicated; SGLT2 inhibitors or GLP-1 receptor agonists preferred with ASCVD, heart failure, or CKD.

Therapeutic drug monitoring is indicated for drugs with narrow therapeutic index and good concentration–effect relationship: digoxin, lithium, phenytoin, tacrolimus, cyclosporine.

Central dogma: DNA → RNA → protein; transcription uses RNA polymerase, translation uses ribosomes, tRNA, and aminoacyl-tRNA synthetases.

Recombinant DNA: restriction endonucleases cleave specific palindromic sequences; ligase joins fragments; plasmids carry origin of replication and selection markers.

PCR cycle: denaturation ~95 °C, annealing ~50–65 °C, extension ~72 °C; Taq polymerase lacks 3′→5′ exonuclease proofreading.

Monoclonal antibodies: hybridoma fusion of B cells with myeloma cells; humanization reduces immunogenicity; IgG1 is common for ADCC effector function.

CRISPR-Cas9 uses a guide RNA to direct Cas9 nuclease to a complementary genomic sequence adjacent to a PAM; creates double-strand breaks repaired by NHEJ or HDR.

Biologic production: CHO cells for glycosylated proteins; E. coli for simple non-glycosylated proteins; purification by protein A affinity, ion exchange, and size exclusion.

Biosimilars require comparability exercises including analytical characterization, functional assays, and clinical pharmacokinetic/pharmacodynamic similarity.

Gene therapy vectors: adeno-associated virus (AAV) for long-term expression, lentivirus for integrating transgenes, adenovirus for transient high-level expression.

Active to passive: move object to subject and use be + past participle; 'The pharmacist dispensed the drug' → 'The drug was dispensed by the pharmacist'.

Reported speech: shift tense back one step (present → past, will → would); time expressions change (today → that day, tomorrow → the next day).

Conditionals: zero (present + present), first (present + will), second (past + would), third (had + past participle + would have + past participle).

Common pharmaceutical collocations: 'administer a dose', 'conduct a trial', 'meet inclusion criteria', 'report an adverse event', 'obtain informed consent'.

Hedging in scientific writing: 'may', 'suggest', 'appear to', 'likely' soften claims; avoid absolute terms unless statistically supported.

Connectors: 'however' contrasts, 'therefore' concludes, 'moreover' adds, 'whereas' compares; use 'due to' before a noun phrase and 'because' before a clause.

Abbreviations in prescriptions: 'q.d.' once daily, 'b.i.d.' twice daily, 't.i.d.' three times daily, 'q.i.d.' four times daily, 'p.r.n.' as needed, 'stat' immediately.

Reading graphs: describe trends with 'increase', 'decrease', 'plateau', 'peak'; specify axes and units; avoid causal language for observational data.

Study designs: randomized controlled trial (causal inference), cohort (incidence, relative risk), case–control (odds ratio, rare outcomes), cross-sectional (prevalence).

Randomization reduces selection bias; allocation concealment prevents foreknowledge; blinding reduces measurement and performance bias.

Sample size for two means: n per group = 2(zα/2 + zβ)²σ²/Δ²; for proportions, use p(1−p) and the desired effect size.

Validity: internal validity concerns whether the study answers its question without bias; external validity concerns generalizability.

Intention-to-treat analysis includes all randomized participants in their assigned groups; per-protocol analysis assesses efficacy under ideal adherence.

CONSORT for randomized trials, STROBE for observational studies, PRISMA for systematic reviews, ARRIVE for animal research.

Informed consent requires capacity, disclosure, understanding, voluntariness, and documentation; vulnerable populations need additional safeguards.

Research ethics: Institutional Review Board/Ethics Committee approval, risk–benefit assessment, confidentiality, and declaration of conflicts of interest.

Descriptive statistics: mean and SD for symmetric data; median and IQR for skewed data; coefficient of variation = SD/mean × 100%.

Standard error of the mean SEM = SD/√n; 95% confidence interval for a mean ≈ mean ± 1.96·SEM (large n).

Hypothesis testing: type I error α (false positive), type II error β (false negative); power = 1 − β.

t-test compares two means; ANOVA compares three or more means; chi-square tests association between categorical variables; nonparametric alternatives are Mann–Whitney and Kruskal–Wallis.

Correlation coefficient r ranges −1 to 1; r² is the proportion of variance explained; correlation does not imply causation.

Linear regression: y = a + bx; slope b is change in y per unit change in x; check residual plots for linearity and homoscedasticity.

Relative risk = incidence in exposed / incidence in unexposed; odds ratio approximates RR when outcome is rare; number needed to treat = 1/absolute risk reduction.

Survival analysis: Kaplan–Meier estimates survival; log-rank test compares curves; Cox proportional hazards model estimates hazard ratios.

Principilism: autonomy, beneficence, nonmaleficence, and justice guide ethical decisions; confidentiality and veracity are derived duties.

Informed consent in pharmacy practice requires the patient to understand risks, benefits, and alternatives before agreeing to treatment.

Conflict of interest: disclose financial relationships with industry; gifts or payments must not influence prescribing or dispensing decisions.

Medication error reporting: nonpunitive reporting systems improve safety; root cause analysis identifies system failures rather than individual blame.

Pharmacist duty to maintain competence through continuing education and to refer when a request exceeds scope of practice.

Patient privacy: protect identifiable health information; share only on a need-to-know basis and with legal authorization.

Research ethics: obtain ethics committee approval, ensure voluntary participation, minimize harm, and report results honestly including negative findings.

Professional boundaries: avoid dual relationships; do not dispense to family or self without safeguards; document interventions accurately.