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RRB Pharmacist Recruitment Exam study materials
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RRB Pharmacist Recruitment Exam practice questions

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Question 1Pharmacology

Which pharmacokinetic parameter represents the fraction of an administered dose of a drug that reaches the systemic circulation unchanged?

  1. Clearance
  2. Volume of distribution
  3. Bioavailability Correct answer.
  4. Half-life

Explanation

Bioavailability (F) is defined as the proportion of the dose that enters the systemic circulation in unchanged form, and for an intravenous dose it is taken as 1. Volume of distribution, clearance and half-life describe distribution and elimination rather than the extent of absorption into plasma.

Question 2Pharmacology

A drug that binds to a receptor and produces a maximal response equal to that of the endogenous ligand is best described as which type of agent?

  1. Full agonist Correct answer.
  2. Inverse agonist
  3. Competitive antagonist
  4. Partial agonist

Explanation

A full agonist has high intrinsic efficacy and can produce the same maximal response as the natural ligand when it occupies the receptor. Partial agonists produce a submaximal response, antagonists produce none, and inverse agonists reduce constitutive activity below baseline.

Question 3Pharmacology

Which enzyme is primarily responsible for the metabolism of most phase I oxidative drug reactions in humans?

  1. Monoamine oxidase
  2. Acetylcholinesterase
  3. Cytochrome P450 system Correct answer.
  4. Xanthine oxidase

Explanation

The cytochrome P450 superfamily, especially the CYP3A4, CYP2D6 and CYP2C subfamilies, mediates most oxidative phase I metabolism of drugs. The other enzymes listed act on specific endogenous or selected exogenous substrates and are not the main route of drug oxidation.

Question 4Pharmacology

Which adverse effect is characteristic of aminoglycoside antibiotics such as gentamicin?

  1. Hepatitis
  2. Cutaneous photosensitivity
  3. Aplastic anaemia
  4. Ototoxicity and nephrotoxicity Correct answer.

Explanation

Aminoglycosides accumulate in cochlear hair cells and proximal tubular cells, producing dose-related ototoxicity and nephrotoxicity that are worsened by prolonged therapy and by concurrent loop diuretics. Their toxicity is not primarily haematological, hepatic or dermatological.

Question 5Pharmacology

Which drug is a selective beta-1 adrenergic antagonist used to reduce heart rate and myocardial oxygen demand in angina?

  1. Prazosin
  2. Atropine
  3. Atenolol Correct answer.
  4. Salbutamol

Explanation

Atenolol is a cardioselective beta-1 antagonist that lowers heart rate, contractility and oxygen demand, making it useful in angina and hypertension. Salbutamol is a beta-2 agonist, prazosin an alpha-1 blocker and atropine a muscarinic antagonist.

Question 6Pharmacology

Which vitamin deficiency is corrected by administering thiamine and classically presents with beriberi or Wernicke encephalopathy?

  1. Vitamin B1 Correct answer.
  2. Vitamin K
  3. Vitamin C
  4. Vitamin B12

Explanation

Thiamine (vitamin B1) is a cofactor for pyruvate dehydrogenase and transketolase, and its deficiency causes dry or wet beriberi and Wernicke-Korsakoff syndrome, especially in chronic alcohol use. The other vitamins listed have different deficiency syndromes.

Question 7Pharmacology

Which route of administration completely avoids first-pass hepatic metabolism?

  1. Sublingual
  2. Intravenous Correct answer.
  3. Oral
  4. Rectal

Explanation

An intravenous dose enters the systemic circulation directly, so it bypasses the gut wall and portal circulation entirely and has 100 percent bioavailability. Oral and rectal routes undergo partial first-pass metabolism, and sublingual absorption avoids it only because venous drainage reaches the systemic circulation, not because the route is intrinsically first-pass free.

Question 8Pharmacology

Which receptor type is a ligand-gated ion channel that mediates fast synaptic transmission?

  1. Ionotropic receptor Correct answer.
  2. G protein-coupled receptor
  3. Nuclear receptor
  4. Tyrosine kinase receptor

Explanation

Ionotropic receptors open an integral ion channel directly upon ligand binding, producing rapid millisecond-scale responses such as those at the nicotinic acetylcholine receptor. G protein-coupled and tyrosine kinase receptors act through second messengers, and nuclear receptors alter gene transcription.

Question 9Pharmacology

A patient on warfarin develops a markedly raised INR with minor bleeding. Which agent most rapidly reverses the anticoagulant effect by replenishing vitamin K-dependent clotting factors?

  1. Protamine sulfate
  2. Fresh frozen plasma or prothrombin complex concentrate Correct answer.
  3. Aspirin
  4. Heparin

Explanation

Warfarin inhibits vitamin K epoxide reductase, lowering functional factors II, VII, IX and X; replacing these factors with fresh frozen plasma or prothrombin complex concentrate corrects coagulopathy fastest, with vitamin K given to sustain reversal. Protamine reverses heparin, not warfarin.

Question 10Pharmacology

A patient taking phenytoin for epilepsy develops gum hypertrophy, hirsutism and ataxia. Which mechanism best explains the ataxia at high plasma concentrations?

  1. Excessive sodium channel blockade in cerebellar pathways Correct answer.
  2. Blockade of muscarinic receptors
  3. Selective dopamine D2 blockade
  4. Inhibition of acetylcholinesterase

Explanation

Phenytoin stabilises neuronal sodium channels, and at supratherapeutic concentrations this effect extends to cerebellar Purkinje cells, producing nystagmus, ataxia and dysarthria. Its gum hypertrophy and hirsutism are chronic cosmetic effects unrelated to dopamine, cholinergic or muscarinic mechanisms.

Question 11Pharmacology

Which statement best explains why a drug with a narrow therapeutic index requires therapeutic drug monitoring?

  1. Therapeutic drug monitoring eliminates the need for dose adjustment
  2. Narrow therapeutic index drugs are never protein bound
  3. Small changes in plasma concentration can cause toxicity or loss of efficacy Correct answer.
  4. Such drugs are always eliminated by zero-order kinetics

Explanation

A narrow therapeutic index means the toxic concentration lies close to the effective concentration, so modest pharmacokinetic variation from interactions, organ impairment or adherence can cause harm or treatment failure. Monitoring keeps concentrations within the therapeutic window.

Question 12Pharmacology

A patient with asthma is prescribed a non-selective beta blocker after myocardial infarction. Which risk is most relevant?

  1. Bradycardia from beta-2 stimulation
  2. Bronchospasm from beta-2 blockade Correct answer.
  3. Hyperglycaemia from alpha-1 blockade
  4. Severe hypertension from beta-1 blockade

Explanation

Non-selective beta blockers block pulmonary beta-2 receptors as well as cardiac beta-1 receptors, which can precipitate bronchoconstriction in susceptible asthmatic patients. Cardioselective agents are preferred when a beta blocker is essential.

Question 13Pharmacology

Which mechanism explains the interaction in which rifampicin reduces the efficacy of oral contraceptives?

  1. Reduced gastric acid secretion impairing absorption
  2. Induction of hepatic CYP3A4 increasing steroid metabolism Correct answer.
  3. Inhibition of CYP3A4 raising steroid levels
  4. Displacement of steroids from plasma protein

Explanation

Rifampicin is a potent inducer of cytochrome P450 enzymes, particularly CYP3A4, and increases the hepatic clearance of oestrogen and progestogen, lowering contraceptive concentrations. Enzyme induction develops over days and persists after rifampicin is stopped.

Question 14Pharmacology

Which diuretic acts on the Na-K-2Cl cotransporter in the thick ascending limb of the loop of Henle?

  1. Hydrochlorothiazide
  2. Acetazolamide
  3. Spironolactone
  4. Furosemide Correct answer.

Explanation

Loop diuretics such as furosemide inhibit the Na-K-2Cl cotransporter in the thick ascending limb, producing the most powerful natriuresis. Thiazides act on the distal convoluted tubule, spironolactone antagonises aldosterone, and acetazolamide inhibits carbonic anhydrase.

Question 15Pharmacology

A patient receiving gentamicin and furosemide develops worsening hearing loss. Which explanation is most plausible?

  1. Additive cochlear toxicity from two ototoxic drugs Correct answer.
  2. Furosemide blocking gentamicin renal excretion
  3. Gentamicin inducing furosemide metabolism
  4. Furosemide inactivating gentamicin in the vial

Explanation

Both aminoglycosides and loop diuretics can damage the cochlea, and their combined use increases the risk of irreversible hearing loss. Monitoring of levels and avoidance of unnecessary concurrent ototoxic agents reduce this risk.

Question 16Pharmacology

Which drug is a proton pump inhibitor that irreversibly inhibits the gastric H+/K+-ATPase?

  1. Misoprostol
  2. Ranitidine
  3. Sucralfate
  4. Omeprazole Correct answer.

Explanation

Omeprazole belongs to the proton pump inhibitor class and covalently binds the H+/K+-ATPase of parietal cells, suppressing acid secretion for prolonged periods. Ranitidine is an H2 blocker, misoprostol a prostaglandin analogue, and sucralfate a mucosal protectant.

Question 17Pharmacology

Why is levodopa usually combined with carbidopa in Parkinson disease?

  1. Carbidopa inhibits peripheral dopa decarboxylase, increasing levodopa delivery to the brain Correct answer.
  2. Carbidopa inhibits monoamine oxidase type B centrally
  3. Carbidopa directly stimulates dopamine receptors in the striatum
  4. Carbidopa blocks the blood-brain barrier to dopamine

Explanation

Carbidopa does not cross the blood-brain barrier and inhibits peripheral aromatic L-amino acid decarboxylase, so more levodopa reaches the central nervous system and peripheral side effects such as nausea are reduced. This allows a lower effective levodopa dose.

Question 18Pharmacology

A patient on lithium for bipolar disorder presents with coarse tremor, vomiting and confusion after starting a thiazide diuretic. Which mechanism explains lithium toxicity?

  1. Thiazides bind lithium in the gut and prevent absorption
  2. Thiazides induce hepatic lithium metabolism
  3. Thiazides increase lithium clearance and lower levels
  4. Thiazides increase renal lithium reabsorption, raising serum levels Correct answer.

Explanation

Lithium is handled like sodium in the kidney, and thiazide-induced sodium loss increases proximal lithium reabsorption, raising serum concentrations into the toxic range. Lithium levels must be monitored closely whenever diuretics are added.

Question 19Pharmacology

Which antibiotic class acts by inhibiting bacterial protein synthesis at the 50S ribosomal subunit?

  1. Macrolides Correct answer.
  2. Fluoroquinolones
  3. Rifamycins
  4. Beta-lactams

Explanation

Macrolides such as erythromycin bind the 50S subunit and block translocation of the peptide chain. Fluoroquinolones inhibit DNA gyrase, beta-lactams inhibit cell wall synthesis, and rifamycins inhibit DNA-dependent RNA polymerase.

Question 20Pharmacology

Which antineoplastic drug is an antimetabolite that inhibits dihydrofolate reductase and requires leucovorin rescue to limit toxicity?

  1. Doxorubicin
  2. Cisplatin
  3. Vincristine
  4. Methotrexate Correct answer.

Explanation

Methotrexate inhibits dihydrofolate reductase and depletes reduced folates needed for thymidylate and purine synthesis; high-dose regimens are followed by leucovorin to bypass the block in normal tissues. The other agents act through DNA alkylation, microtubule disruption or intercalation.

Question 21Pharmacology

A drug has a volume of distribution of 40 L and a clearance of 5 L/h. What is its elimination half-life?

  1. About 5.5 hours Correct answer.
  2. About 2 hours
  3. About 20 hours
  4. About 8 hours

Explanation

Half-life equals 0.693 multiplied by volume of distribution divided by clearance, so 0.693 times 40 divided by 5 gives approximately 5.5 hours. This relationship shows that half-life rises with larger distribution volume or falls with higher clearance.

Question 22Pharmacology

Which statement best explains why a competitive antagonist shifts the agonist dose-response curve to the right without reducing the maximal response?

  1. The antagonist reduces the intrinsic efficacy of the agonist
  2. The antagonist permanently destroys receptor binding sites
  3. The antagonism is surmountable because higher agonist concentrations can outcompete the antagonist at the receptor Correct answer.
  4. The antagonist blocks a site distal to the receptor

Explanation

Competitive antagonists bind reversibly at the same site as the agonist, so increasing agonist concentration restores occupancy and the same maximal effect is achieved, though at higher doses. Non-competitive antagonists, by contrast, depress the maximal response.

Question 23Pharmacology

A patient with severe sepsis is started on vancomycin and piperacillin-tazobactam and later develops acute kidney injury. Which pharmacokinetic consequence most directly requires dose adjustment of renally cleared drugs?

  1. Increased volume of distribution shortening half-life
  2. Reduced clearance prolonging elimination half-life Correct answer.
  3. Reduced protein binding increasing total clearance
  4. Increased hepatic metabolism lowering plasma levels

Explanation

Acute kidney injury lowers renal clearance, so renally eliminated drugs accumulate and their half-life lengthens, raising toxicity risk unless doses are reduced or intervals extended. Therapeutic drug monitoring is particularly important for agents such as vancomycin.

Question 24Pharmacology

Which mechanism underlies the antihypertensive effect of ACE inhibitors beyond blood pressure reduction, contributing to their renoprotective action in diabetic nephropathy?

  1. Reduced angiotensin II-mediated efferent arteriolar constriction lowering intraglomerular pressure Correct answer.
  2. Increased bradykinin degradation by angiotensin-converting enzyme
  3. Blockade of aldosterone receptors in the collecting duct
  4. Direct inhibition of sodium reabsorption in the proximal tubule

Explanation

By lowering angiotensin II, ACE inhibitors dilate the efferent arteriole and reduce intraglomerular pressure, which decreases proteinuria and slows progression of diabetic nephropathy. The rise in bradykinin is a side-effect mechanism, not the renoprotective one.

Question 25Pharmacology

A patient on isoniazid develops peripheral neuropathy. Which intervention best addresses the underlying mechanism?

  1. Administer vitamin K to restore clotting factor synthesis
  2. Add rifampicin to accelerate isoniazid clearance
  3. Supplement pyridoxine to correct isoniazid-induced vitamin B6 deficiency Correct answer.
  4. Increase the isoniazid dose to overcome enzyme induction

Explanation

Isoniazid interferes with pyridoxine metabolism and increases vitamin B6 excretion, causing a neuropathy that is prevented or treated with pyridoxine supplementation. Dose reduction or discontinuation may also be needed if symptoms persist.

Question 26Pharmacology

Which pharmacokinetic parameter describes the fraction of an administered dose of a drug that reaches the systemic circulation unchanged?

  1. Volume of distribution
  2. Clearance
  3. Half-life
  4. Bioavailability Correct answer.

Explanation

Bioavailability (F) is defined as the proportion of an administered dose that enters the systemic circulation in an unchanged form, and for an intravenous dose it is taken as 100%. It is reduced by incomplete absorption and by first-pass metabolism in the gut wall and liver. The other listed parameters describe distribution, elimination efficiency and the time course of decline, not the extent of absorption.

Question 27Pharmacology

A drug is a weak acid with a pKa of 4.0. In the acidic environment of the stomach (pH approximately 1.4), which statement best describes its ionisation and membrane permeation?

  1. It is largely ionised and therefore trapped within the gastric lumen
  2. It is largely unionised and therefore more lipid-permeable across gastric mucosa Correct answer.
  3. It is largely unionised but cannot cross lipid membranes
  4. It is largely ionised and therefore more lipid-permeable across gastric mucosa

Explanation

By the Henderson-Hasselbalch relationship for a weak acid, when the environmental pH is well below the pKa the equilibrium favours the protonated, unionised form. The unionised species is more lipid-soluble and diffuses across biological membranes more readily than the charged species. Hence weak acids are predominantly unionised in the strongly acidic stomach, which favours their absorption there.

Question 28Pharmacology

A patient on a stable maintenance dose of an oral antiepileptic develops sedation and diplopia after starting a second drug that inhibits cytochrome P450 enzymes. Which mechanism best explains the observed toxicity?

  1. Induction of hepatic enzymes that accelerate metabolism of the antiepileptic
  2. Displacement of the antiepileptic from plasma albumin with increased glomerular filtration
  3. Reduced absorption of the antiepileptic from the gastrointestinal tract
  4. Reduced hepatic clearance of the antiepileptic, raising its steady-state plasma concentration Correct answer.

Explanation

Enzyme inhibition reduces the intrinsic clearance of a drug that is eliminated by hepatic metabolism, so at an unchanged dosing rate the steady-state concentration rises in proportion to the fall in clearance. Higher plasma concentrations then produce dose-related adverse effects such as sedation and diplopia. This is a pharmacokinetic interaction based on altered metabolism rather than on protein binding or absorption.

Question 29Pharmacology

A patient with myasthenia gravis is given neostigmine. Which mechanism accounts for the improvement in muscle strength?

  1. Competitive blockade of nicotinic acetylcholine receptors at the motor end plate
  2. Depletion of presynaptic acetylcholine stores in the motor nerve terminal
  3. Blockade of voltage-gated sodium channels in the skeletal muscle membrane
  4. Reversible inhibition of acetylcholinesterase, increasing acetylcholine at the neuromuscular junction Correct answer.

Explanation

Neostigmine reversibly inhibits acetylcholinesterase, so acetylcholine released at the motor end plate is not broken down as rapidly and accumulates in the synaptic cleft. The increased transmitter concentration competes with the receptor deficit in myasthenia gravis and improves neuromuscular transmission. This is why cholinesterase inhibitors are used, with atropine given to limit muscarinic effects.

Question 30Pharmacology

Which mechanism best explains why low-dose aspirin is used for prophylaxis of arterial thrombosis while higher analgesic doses are avoided long term?

  1. Inhibition of vitamin K epoxide reductase reduces synthesis of clotting factors
  2. Irreversible acetylation of platelet cyclooxygenase-1 selectively suppresses thromboxane A2 with minimal prostacyclin loss Correct answer.
  3. Reversible inhibition of cyclooxygenase-2 reduces vascular inflammation without affecting platelet function
  4. Blockade of platelet ADP receptors prevents aggregation independently of prostaglandin synthesis

Explanation

Aspirin irreversibly acetylates cyclooxygenase-1, and because platelets cannot synthesise new enzyme, a low dose suppresses thromboxane A2 production for the platelet lifespan. At these low doses, endothelial cyclooxygenase-2 can still generate prostacyclin, so the antithrombotic effect predominates. Higher doses also inhibit vascular prostacyclin and add gastrointestinal toxicity without proportional antithrombotic benefit.

Question 31Pharmacology

A patient with hypertension and type 2 diabetes is started on a drug that reduces cardiovascular events and slows progression of diabetic nephropathy. Which drug class acts by blocking the angiotensin II type 1 receptor directly?

  1. Angiotensin receptor blockers Correct answer.
  2. Direct renin inhibitors
  3. Thiazide diuretics
  4. Angiotensin-converting enzyme inhibitors

Explanation

Angiotensin receptor blockers such as losartan and telmisartan antagonise the angiotensin II type 1 receptor, lowering blood pressure and reducing glomerular pressure and albuminuria. Because they do not inhibit kinin breakdown, they cause cough less often than ACE inhibitors. Their renoprotective and cardiovascular benefits in diabetic patients are well established.

Question 32Pharmacology

A patient with organophosphate poisoning presents with bradycardia, bronchorrhoea, miosis and muscle fasciculations. Atropine is given but fasciculations persist. Which additional agent is most appropriate and why?

  1. Neostigmine, because it restores acetylcholinesterase activity at the neuromuscular junction
  2. Atropine at a higher dose, because it also blocks nicotinic receptors at the motor end plate
  3. Pralidoxime, because it reactivates phosphorylated acetylcholinesterase before enzyme ageing becomes irreversible Correct answer.
  4. Succinylcholine, because it prevents acetylcholine release from the motor nerve terminal

Explanation

Organophosphates phosphorylate acetylcholinesterase; oximes such as pralidoxime remove the phosphate group and restore enzyme activity if given before ageing (dealkylation) makes the bond irreversible. Atropine antagonises muscarinic effects only and does not relieve nicotinic features such as fasciculations and weakness. Hence an oxime is added early alongside atropine and supportive care.

Question 33Pharmaceutics (including dosage forms, formulation and dispensing)

Which pharmaceutical dosage form is defined as a liquid preparation in which solid drug particles are dispersed in a liquid vehicle and are intended to be shaken before use?

  1. Syrup
  2. Solution
  3. Elixir
  4. Suspension Correct answer.

Explanation

A suspension contains insoluble solid drug particles dispersed throughout a liquid vehicle, so it separates on standing and must be shaken to redistribute the particles and ensure dose uniformity. Solutions and elixirs are molecularly dispersed and do not require shaking.

Question 34Pharmaceutics (including dosage forms, formulation and dispensing)

In tablet formulation, which excipient is added primarily to promote the breakup of the tablet into granules and particles after ingestion?

  1. Binder
  2. Glidant
  3. Disintegrant Correct answer.
  4. Lubricant

Explanation

Disintegrants draw in water and swell or wick, breaking the compacted tablet into smaller fragments and increasing the surface area available for dissolution. Binders hold granules together, glidants improve powder flow, and lubricants reduce friction during compression.

Question 35Pharmaceutics (including dosage forms, formulation and dispensing)

Which route of administration completely avoids the hepatic first-pass effect?

  1. Oral
  2. Rectal (upper rectum)
  3. Enteric-coated oral
  4. Sublingual Correct answer.

Explanation

Drug absorbed from the sublingual mucosa drains into the venous system that reaches the systemic circulation without passing through the liver, so first-pass hepatic metabolism is bypassed. Oral and enteric-coated products are absorbed into the portal circulation, and drug absorbed from the upper rectum drains partly into the portal vein.

Question 36Pharmaceutics (including dosage forms, formulation and dispensing)

Which statement correctly describes the term 'bioavailability' as used in pharmaceutics?

  1. The proportion of an administered dose that reaches systemic circulation unchanged, together with the rate at which it does so Correct answer.
  2. The total amount of drug bound to plasma albumin at steady state
  3. The fraction of drug excreted unchanged in the urine
  4. The speed at which a tablet dissolves in the dissolution apparatus

Explanation

Bioavailability describes both the extent (fraction of dose) and the rate at which unchanged drug reaches the systemic circulation from a dosage form. It is assessed against an intravenous reference for absolute bioavailability.

Question 37Pharmaceutics (including dosage forms, formulation and dispensing)

A prescription calls for 2% w/w hydrocortisone cream and 60 g is required. What mass of hydrocortisone is needed?

  1. 0.12 g
  2. 1.2 g Correct answer.
  3. 0.012 g
  4. 12 g

Explanation

Percent weight-in-weight means grams of solute per 100 g of preparation, so 2% w/w contains 2 g in 100 g. For 60 g the amount is 2 × 60/100 = 1.2 g.

Question 38Pharmaceutics (including dosage forms, formulation and dispensing)

Which container closure is specifically designed to prevent children from opening it, as required for many oral prescription medicines?

  1. Amber glass bottle with a screw cap
  2. Child-resistant closure Correct answer.
  3. Single-use sachet
  4. Unit-dose blister pack

Explanation

Child-resistant closures require a coordinated action, such as push-and-turn, that young children are generally unable to perform, reducing accidental ingestion. Amber glass, blisters, and sachets address light protection, unit dosing, or stability rather than child resistance.

Question 39Pharmaceutics (including dosage forms, formulation and dispensing)

In the context of sterile products, which term means that a product is free from viable microorganisms?

  1. Sterile Correct answer.
  2. Aseptic
  3. Isotonic
  4. Pyrogen-free

Explanation

Sterility means the absence of viable microorganisms. Aseptic refers to techniques that avoid contamination during preparation, pyrogen-free means absence of fever-producing substances, and isotonic refers to osmotic equivalence with body fluids.

Question 40Pharmaceutics (including dosage forms, formulation and dispensing)

Which unit operation is used to reduce the particle size of a dry powder by impact and attrition in a rotating drum containing grinding media?

  1. Ball milling Correct answer.
  2. Sieving
  3. Fluidised bed drying
  4. Lyophilisation

Explanation

A ball mill reduces particle size by impact and attrition as grinding media tumble inside a rotating drum. Sieving separates particles by size without reducing them, while drying operations remove solvent.

Question 41Pharmaceutics (including dosage forms, formulation and dispensing)

A prescription requests 500 mL of a 1 in 4000 w/v solution of a drug. What mass of drug is required?

  1. 12.5 g
  2. 0.0125 g
  3. 0.125 g Correct answer.
  4. 1.25 g

Explanation

A 1 in 4000 w/v solution contains 1 g in 4000 mL. Therefore 500 mL contains 500/4000 = 0.125 g of drug.

Question 42Pharmaceutics (including dosage forms, formulation and dispensing)

Which mechanism best explains why adding a co-solvent such as ethanol increases the solubility of a poorly water-soluble drug in an oral solution?

  1. It lowers the dielectric constant of the vehicle and reduces the polarity of the solvent system Correct answer.
  2. It increases the ionic strength of the vehicle
  3. It promotes crystallisation of the drug
  4. It raises the pH of the vehicle

Explanation

Water-miscible co-solvents such as ethanol lower the overall polarity and dielectric constant of the vehicle, improving solvation of less polar drug molecules. This is the basis of hydroalcoholic elixirs and similar solutions.

Question 43Pharmaceutics (including dosage forms, formulation and dispensing)

Which statement about the properties of a valid suppository base is correct?

  1. It should be water-soluble to guarantee rapid release
  2. It should melt at body temperature and be non-irritant to the rectal mucosa Correct answer.
  3. It should remain solid at 45 degrees Celsius to prevent leakage
  4. It should react chemically with the drug to aid absorption

Explanation

An ideal suppository base softens or melts at rectal temperature, is non-irritant, and is compatible with the drug. Bases such as theobroma oil melt near 37 degrees Celsius, while PEG bases dissolve rather than melt.

Question 44Pharmaceutics (including dosage forms, formulation and dispensing)

Which factor most directly reduces the bioavailability of a drug formulated as a sustained-release matrix tablet?

  1. Reduction of the dose administered
  2. Rapid disintegration of the matrix in the stomach
  3. Dose dumping caused by a defective matrix
  4. Slow erosion or diffusion of drug from the matrix Correct answer.

Explanation

Sustained-release matrices rely on controlled diffusion or erosion, so a slower release rate can limit the fraction absorbed, especially for drugs with low permeability or a narrow absorption window. Dose dumping is the opposite problem, an uncontrolled rapid release.

Question 45Pharmaceutics (including dosage forms, formulation and dispensing)

Which excipient is included in a parenteral formulation specifically to adjust the tonicity of the solution to approximately that of blood?

  1. Sodium chloride Correct answer.
  2. Benzyl alcohol
  3. Disodium edetate
  4. Sodium metabisulfite

Explanation

Sodium chloride is a common tonicity-adjusting agent used to make injections approximately isotonic with blood, reducing pain and haemolysis on administration. Benzyl alcohol is a preservative, metabisulfite an antioxidant, and edetate a chelating agent.

Question 46Pharmaceutics (including dosage forms, formulation and dispensing)

A pharmacist prepares 200 mL of a syrup containing 10% w/v of a drug. If 50 mL of a 40% w/v stock solution is used, what volume of water should be added to make up the final volume?

  1. 200 mL
  2. 100 mL
  3. 50 mL
  4. 150 mL Correct answer.

Explanation

The 200 mL of 10% w/v syrup contains 20 g of drug. The 50 mL of 40% w/v stock contains 20 g, so the stock provides all the drug and the final volume is made up with 200 − 50 = 150 mL of water.

Question 47Pharmaceutics (including dosage forms, formulation and dispensing)

Which statement about the use of a volumetric flask in dispensing is correct?

  1. It is calibrated to deliver its nominal volume by free drainage
  2. It is suitable for heating solutions to boiling during preparation
  3. It is used to measure small volumes of viscous liquids accurately
  4. It is calibrated to contain a specified volume when filled to the mark at the stated temperature Correct answer.

Explanation

A volumetric flask is calibrated 'to contain' its nominal volume when the meniscus is at the calibration mark at the specified temperature, usually 20 degrees Celsius. It is used for accurate dilution to a fixed final volume.

Question 48Pharmaceutics (including dosage forms, formulation and dispensing)

Which statement about the difference between a lotion and a liniment is correct?

  1. A lotion is applied to unbroken skin without friction, while a liniment is applied with friction to the skin Correct answer.
  2. A liniment is intended for oral administration
  3. A lotion is always sterile, while a liniment is not
  4. A lotion is a solid dosage form, while a liniment is a liquid

Explanation

In traditional dispensing terminology, a lotion is a liquid or semi-liquid preparation applied to unbroken skin without rubbing, whereas a liniment is applied with friction to the skin surface. Neither is defined by sterility or oral use.

Question 49Pharmaceutics (including dosage forms, formulation and dispensing)

Why is a preservative such as benzalkonium chloride commonly included in an ophthalmic solution?

  1. To adjust the pH of the eye
  2. To increase the viscosity of the tears
  3. To act as a tonicity agent
  4. To maintain sterility of the preparation during multiple-dose use Correct answer.

Explanation

Preservatives in multi-dose ophthalmic solutions inhibit microbial growth after the container is opened, helping maintain sterility during use. Viscosity, pH, and tonicity are adjusted by other excipients.

Question 50Pharmaceutics (including dosage forms, formulation and dispensing)

A hard gelatin capsule is to be filled with 300 mg of powder of bulk density 0.6 g/mL. What approximate capsule volume is required?

  1. 1.8 mL
  2. 5 mL
  3. 0.18 mL
  4. 0.5 mL Correct answer.

Explanation

Volume equals mass divided by bulk density, so 0.3 g ÷ 0.6 g/mL = 0.5 mL. The capsule size must be selected so its body volume accommodates this fill volume.