NPC D.Pharm cheat sheet

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

First-pass hepatic extraction reduces oral bioavailability: F = f × (1 − E_H), where f is the fraction absorbed and E_H the hepatic extraction ratio.

Noyes–Whitney equation: dissolution rate dM/dt = (D·A/h)(C_s − C), so reducing particle size raises A and dissolution rate.

Henderson–Hasselbalch: for weak acids pH = pKa + log([A⁻]/[HA]); a weak acid is 50% ionized when pH = pKa.

Stokes' law sedimentation velocity v = d²(ρ_p − ρ_l)g/18η; smaller particles and higher viscosity slow sedimentation in suspensions.

Zero-order release delivers drug at a constant rate independent of concentration; first-order release rate is proportional to remaining amount.

Shelf-life t90 = 0.105/k for first-order degradation; k is the apparent first-order rate constant at the stated storage temperature.

Tablet hardness, friability (<1% weight loss), and disintegration time are the core pharmacopoeial quality tests for compressed tablets.

HLB scale: 3–6 favors w/o emulsifiers, 8–18 favors o/w emulsifiers; blend HLB is the weight-weighted average of components.

Receptor families: Gs-coupled raise cAMP, Gi-coupled lower cAMP, Gq-coupled raise IP3/DAG and intracellular Ca²⁺; ligand-gated channels act in milliseconds.

Competitive antagonists shift the dose–response curve right without lowering Emax; non-competitive antagonists reduce Emax.

Therapeutic index = TD50/ED50; a low index (e.g., digoxin, warfarin, lithium) mandates therapeutic drug monitoring.

Pharmacokinetic formulas: Vd = Dose/C0; CL = k × Vd; t½ = 0.693 × Vd/CL.

CYP3A4 metabolizes roughly half of marketed drugs; inhibitors (ketoconazole, clarithromycin, grapefruit) raise substrate levels, inducers (rifampicin, carbamazepine) lower them.

Aminoglycosides are concentration-dependent bactericidal agents; once-daily dosing exploits the post-antibiotic effect while limiting nephrotoxicity.

Beta-blockers reduce mortality in heart failure (bisoprolol, carvedilol, metoprolol succinate); non-selective agents are avoided in asthma.

NSAIDs inhibit COX, reducing renal prostaglandins; risk of acute kidney injury rises with dehydration, ACE inhibitors, and diuretics ('triple whammy').

Adrenaline is first-line in anaphylaxis: 0.5 mg IM (1:1000) into the anterolateral thigh, repeated every 5 minutes as needed.

Prescription legal elements: prescriber name, registration number, date, patient details, drug name, strength, dosage form, quantity, directions, and signature.

Hospital formulary decisions use safety, efficacy, quality, cost, and availability; the Pharmacy and Therapeutics Committee governs additions and deletions.

High-alert medications (concentrated potassium chloride, insulin, heparin, chemotherapy, opioids) require independent double-checks and segregated storage.

LASA (look-alike/sound-alike) drugs such as hydralazine–hydroxyzine need tall-man lettering and physical separation on shelves.

Cytotoxic preparation requires a Class II biological safety cabinet, closed-system transfer devices, PPE, and spill-kit availability.

Medication reconciliation at admission, transfer, and discharge reduces unintended discrepancies; the best possible medication history is its foundation.

Cold-chain products (most vaccines, insulin) are stored at 2–8 °C; freezing damages adjuvanted vaccines and insulin.

Pharmacovigilance reporting uses the WHO-UMC causality scale (certain, probable, possible, unlikely) and Naranjo scoring for assessment.

A prescription-only medicine may be dispensed only against a valid prescription from a registered medical practitioner; schedule classification determines control level.

Narcotic and psychotropic substances require separate record-keeping, double-locked storage, and prescription retention per national narcotics rules.

Pharmacist registration is time-limited and renewable; practising without current registration is an offence.

Pharmacist ethics: informed consent, confidentiality, avoiding conflicts of interest, and refusing to dispense when the prescription is unsafe or forged.

Expired, adulterated, misbranded, and spurious drugs are distinct legal categories; spurious drugs are deliberately mislabelled as another product.

Label requirements typically include drug name, strength, batch number, manufacturing and expiry dates, storage conditions, and manufacturer details.

Adverse drug reaction reporting to the national pharmacovigilance centre is a professional obligation even for suspected, unproven reactions.

Substitution of a prescribed brand requires prescriber consent or explicit legal permission; generic substitution rules vary by jurisdiction.

Beer–Lambert law: A = εbc; absorbance is linear with concentration only in dilute solution and at fixed wavelength and path length.

UV–visible quantification uses λmax; a calibration curve of absorbance versus concentration gives the unknown concentration by interpolation.

IR spectroscopy identifies functional groups: O–H broad 3200–3600 cm⁻¹, C=O 1700–1750 cm⁻¹, N–H 3300–3500 cm⁻¹.

HPLC parameters: retention time, resolution ≥2 between critical pairs, tailing factor 0.9–1.1, and theoretical plates measure column efficiency.

Titration formulas: % purity = (V × N × Eq.wt × 100)/weight of sample; back titration is used when the reaction is slow or the endpoint unclear.

Karl Fischer titration measures water content; loss on drying measures total volatile matter, so the two are not interchangeable.

ICH Q1A stability testing: long-term 25 °C/60% RH, accelerated 40 °C/75% RH for 6 months, with intermediate conditions when accelerated data show change.

Chirality: enantiomers differ in biological activity (e.g., S-warfarin is more potent than R-warfarin) but share identical achiral analytical properties.

Patient counselling (Indian/standard model) covers drug name, purpose, dose, timing, duration, storage, and what to do about missed doses.

Inhaler technique: shake, exhale fully, seal lips, actuate at start of inspiration, hold breath ~10 seconds, rinse mouth after corticosteroid inhalers.

Oral rehydration solution composition: sodium 75 mmol/L, glucose 75 mmol/L, potassium 20 mmol/L, citrate 10 mmol/L, chloride 65 mmol/L.

Antibiotic counselling must stress completing the full course and avoiding sharing; non-adherence drives resistance.

Self-medication risks include masking serious disease, drug interactions, and antimicrobial resistance; refer red-flag symptoms to a prescriber.

Blood pressure targets for most adults are below 140/90 mmHg; home monitoring requires 5 minutes rest, correct cuff size, and two readings.

Diabetes education: HbA1c reflects 2–3 months of glycaemia; hypoglycaemia (glucose <70 mg/dL) needs 15 g fast carbohydrate and recheck in 15 minutes.

Smoking cessation: combination of behavioural support plus varenicline, bupropion, or nicotine replacement is more effective than either alone.