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Lebanon Pharmacy Colloquium practice questions

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Question 1Pharmaceutics and Pharmaceutical Technology

Which pharmacopoeial test is used to assess the uniformity of content of individual dosage units in a batch of tablets?

  1. Friability test
  2. Disintegration test
  3. Hardness test
  4. Content uniformity test Correct answer.

Explanation

Content uniformity measures the amount of active ingredient in individual units to confirm that the drug is distributed evenly between tablets. It is distinct from weight variation, which only reflects total mass. Friability, disintegration and hardness describe physical rather than dose-related properties.

Question 2Pharmaceutics and Pharmaceutical Technology

A tablet formulation contains lactose, microcrystalline cellulose, croscarmellose sodium, magnesium stearate and the active ingredient. Which component acts primarily as the disintegrant?

  1. Croscarmellose sodium Correct answer.
  2. Microcrystalline cellulose
  3. Lactose
  4. Magnesium stearate

Explanation

Croscarmellose sodium is a superdisintegrant that swells on contact with aqueous fluid and breaks the tablet into granules. Lactose is a diluent, microcrystalline cellulose is a dry binder or diluent, and magnesium stearate is a lubricant. Only croscarmellose sodium has disintegration as its principal function.

Question 3Pharmaceutics and Pharmaceutical Technology

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

  1. Oral immediate-release tablet
  2. Oral enteric-coated tablet
  3. Rectal suppository placed in the lower rectum
  4. Intravenous bolus injection Correct answer.

Explanation

An intravenous bolus delivers drug directly into the systemic circulation, so the entire dose reaches the blood without passing through the liver first. Oral dosage forms, even enteric-coated ones, are absorbed into the portal circulation and undergo hepatic first-pass metabolism. Lower rectal absorption partially bypasses the liver but is not complete.

Question 4Pharmaceutics and Pharmaceutical Technology

In a zero-order release system, the rate of drug release is best described as which of the following?

  1. Inversely proportional to the square of time
  2. Proportional to the amount of drug remaining in the device
  3. Independent of the amount of drug remaining in the device Correct answer.
  4. Proportional to the square root of time

Explanation

Zero-order kinetics means a constant amount of drug is released per unit time, so the rate does not depend on the concentration remaining in the device. This is the goal of many controlled-release designs because plasma levels stay stable. First-order and matrix-diffusion systems show concentration- or time-dependent rates.

Question 5Pharmaceutics and Pharmaceutical Technology

Which property of a powder is measured by the angle of repose?

  1. True density
  2. Moisture content
  3. Particle size distribution
  4. Flowability Correct answer.

Explanation

The angle of repose is the angle formed by a heap of powder poured onto a surface; a low angle indicates good flow and a steep angle indicates poor flow. It is a bulk flow indicator used in capsule and tablet filling decisions. Particle size, moisture and density influence flow but are measured by other techniques.

Question 6Pharmaceutics and Pharmaceutical Technology

Which sterilization method is appropriate for a heat-labile ophthalmic solution supplied in a sealed plastic container?

  1. Moist heat autoclaving at 121 degrees Celsius
  2. Gamma irradiation at 25 kGy
  3. Aseptic filtration through a 0.22 micrometre membrane followed by aseptic filling Correct answer.
  4. Dry heat sterilization at 160 degrees Celsius

Explanation

Filtration through a 0.22 micrometre membrane removes bacteria without exposing the product to heat, which suits heat-labile drugs. Aseptic handling after filtration prevents recontamination. Autoclaving and dry heat would degrade the drug, and gamma irradiation is generally unsuitable for aqueous solutions in plastic because of radiation-induced degradation.

Question 7Pharmaceutics and Pharmaceutical Technology

Which of the following best describes the purpose of a bioadhesive mucoadhesive polymer in a buccal tablet?

  1. To reduce the drug's aqueous solubility
  2. To prolong contact time with the buccal mucosa and improve absorption Correct answer.
  3. To accelerate first-pass metabolism
  4. To increase the bitterness of the formulation

Explanation

Mucoadhesive polymers such as carbomers or chitosan hydrate and adhere to the mucosal surface, keeping the dosage form in place so drug can diffuse across the epithelium. Longer residence time raises the fraction absorbed and allows a sustained effect. Bioadhesion does not alter hepatic metabolism or intentionally change taste.

Question 8Pharmaceutics and Pharmaceutical Technology

A pharmacist must prepare a 2 percent w/w hydrocortisone cream from a 5 percent w/w stock cream and a plain cream base. How many grams of the 5 percent cream are needed to prepare 120 g of the 2 percent cream?

  1. 60 g
  2. 24 g
  3. 48 g Correct answer.
  4. 72 g

Explanation

Using the alligation or dilution equation, the mass of drug required is 2 percent of 120 g, which equals 2.4 g. Dividing this by the stock concentration of 0.05 gives 48 g of the 5 percent cream, with the remaining 72 g being base. This confirms the dilution calculation.

Question 9Pharmaceutics and Pharmaceutical Technology

Which excipient is added to a tablet formulation primarily to improve the flow of granules from the hopper into the die cavity?

  1. Binder
  2. Colourant
  3. Plasticizer
  4. Glidant Correct answer.

Explanation

A glidant such as colloidal silicon dioxide reduces interparticle friction and improves powder flow into the die. Binders promote granule cohesion, colourants provide identification, and plasticizers are used in film coatings. Only the glidant is added specifically to improve flow.

Question 10Pharmaceutics and Pharmaceutical Technology

A drug has a hepatic extraction ratio of 0.85 and is given orally. Which statement best predicts the consequence of this value?

  1. Oral bioavailability will be low because most absorbed drug is removed by the liver Correct answer.
  2. Oral bioavailability will be high because absorption is complete
  3. Oral bioavailability will be unaffected by hepatic blood flow
  4. Oral bioavailability will equal the fraction absorbed

Explanation

The fraction escaping hepatic metabolism after oral absorption is approximately one minus the extraction ratio, so only about 15 percent of absorbed drug reaches systemic circulation. High extraction therefore produces low oral bioavailability and makes the drug sensitive to changes in hepatic blood flow. Complete absorption does not guarantee high systemic availability.

Question 11Pharmaceutics and Pharmaceutical Technology

During wet granulation, which change would most likely reduce granule friability while maintaining acceptable compressibility?

  1. Reducing the granulation liquid temperature to near freezing
  2. Increasing the magnesium stearate level substantially
  3. Increasing the binder solution volume within a reasonable range Correct answer.
  4. Removing all binder from the formulation

Explanation

Adding more binder solution increases the amount of binder bridges between particles, producing stronger, less friable granules. Excessive lubricant weakens interparticle bonding, and removing binder eliminates the very bridges that give strength. Freezing the liquid would interfere with uniform wetting and granulation.

Question 12Pharmaceutics and Pharmaceutical Technology

Which statement correctly describes the difference between a suspension and an emulsion?

  1. A suspension requires an emulsifying agent, whereas an emulsion requires a suspending agent
  2. A suspension is always transparent, whereas an emulsion is always opaque
  3. A suspension contains only gases, whereas an emulsion contains only solids
  4. A suspension is a dispersion of solid particles, whereas an emulsion is a dispersion of two immiscible liquids Correct answer.

Explanation

A suspension contains solid drug particles dispersed in a liquid vehicle, while an emulsion contains droplets of one immiscible liquid dispersed in another. Sedimentation and Ostwald ripening are typical instability problems for the two systems respectively. Both are heterogeneous systems but differ in the physical state of the dispersed phase.

Question 13Pharmaceutics and Pharmaceutical Technology

In a first-order degradation study, a drug solution loses 10 percent of its initial concentration in 12 months at 25 degrees Celsius. What is the approximate half-life of the drug under these conditions?

  1. About 12 months
  2. About 120 months
  3. About 76 months Correct answer.
  4. About 38 months

Explanation

For first-order kinetics, the fraction remaining after time t is exp(-kt), so k equals minus the natural logarithm of 0.90 divided by 12 months, giving about 0.00878 per month. The half-life is ln2 divided by k, which is approximately 79 months, closest to 76 months among the choices. A rough estimate also follows from 12 months per 10 percent loss and about 70 percent loss to reach half-life.

Question 14Pharmaceutics and Pharmaceutical Technology

Which factor most strongly increases the rate of oxidation of a drug in aqueous solution?

  1. Storage in amber glass at low temperature
  2. Replacement of dissolved oxygen with nitrogen
  3. Presence of trace heavy metal ions such as copper and iron Correct answer.
  4. Addition of a chelating agent such as EDTA

Explanation

Trace transition metal ions catalyse autoxidation by promoting radical formation, so they markedly accelerate oxidative degradation. Chelating agents, oxygen displacement and cool dark storage all slow oxidation. Therefore the presence of heavy metal ions is the factor that increases the rate.

Question 15Pharmaceutics and Pharmaceutical Technology

A sustained-release matrix tablet is formulated with hydroxypropyl methylcellulose. Which mechanism primarily controls drug release from this system?

  1. Enzymatic cleavage of the polymer backbone
  2. Immediate dissolution of the polymer shell
  3. Hydration and gel-layer formation followed by diffusion through the gel Correct answer.
  4. Osmotic pumping through a laser-drilled orifice

Explanation

Hydrophilic matrix polymers hydrate at the tablet surface to form a viscous gel layer through which dissolved drug diffuses, and the gel layer erodes gradually. Release is therefore controlled by gel diffusion and erosion. Osmotic pumping requires a semipermeable membrane and delivery orifice, which this system lacks.

Question 16Pharmaceutics and Pharmaceutical Technology

Which particle size reduction method is most appropriate for a heat-sensitive crystalline drug that must be micronized for a dry powder inhaler?

  1. Jet milling with compressed air Correct answer.
  2. Dry heat sterilization followed by grinding
  3. Ball milling for several hours with heating
  4. Spray drying from a hot organic solvent

Explanation

Jet mills use high-velocity gas streams to cause particle collision and attrition with little heat buildup, which suits heat-sensitive compounds intended for inhalation. Ball milling generates frictional heat over long periods, and spray drying from hot solvent exposes the drug to thermal stress. Dry heat treatment would degrade the drug.

Question 17Pharmaceutics and Pharmaceutical Technology

A suppository base melts at body temperature and is used for a drug that is slightly soluble in the base. Which formulation strategy best improves drug release from the suppository?

  1. Compressing the suppository under high pressure
  2. Adding a hydrophobic wax to raise the melting point
  3. Increasing the proportion of base to dilute the drug
  4. Reducing the drug particle size to increase surface area Correct answer.

Explanation

Reducing particle size increases the surface area available for dissolution in the melted base and in rectal fluid, which speeds release and absorption. Diluting the drug lowers the dose per unit, and adding hydrophobic wax or compression does not enhance release. Smaller particles are the standard approach for poorly soluble drugs in suppositories.

Question 18Pharmaceutics and Pharmaceutical Technology

Which statement correctly explains why a drug with a high log P may show poor oral absorption despite good membrane permeability?

  1. High lipophilicity can limit dissolution in gastrointestinal fluid and reduce the free concentration available for absorption Correct answer.
  2. High log P prevents the drug from crossing lipid bilayers
  3. High lipophilicity always increases aqueous solubility
  4. High log P means the drug is actively pumped out of enterocytes

Explanation

Very lipophilic compounds dissolve poorly in the aqueous contents of the gut, so dissolution rather than permeability becomes rate-limiting and overall absorption falls. Lipophilicity favours passive membrane diffusion but not aqueous dissolution. Efflux transport and bilayer impermeability are separate phenomena not implied by a high log P.

Question 19Pharmaceutics and Pharmaceutical Technology

Which is the primary reason for performing a fluid-bed drying step after wet granulation rather than tray drying?

  1. Fluid-bed drying provides faster and more uniform drying through intimate contact between hot air and granules Correct answer.
  2. Fluid-bed drying sterilizes the granules
  3. Fluid-bed drying eliminates the need for a binder
  4. Fluid-bed drying increases the moisture content of the granules

Explanation

In fluid-bed drying, hot air suspends the granules so each particle contacts the drying medium, giving rapid and uniform moisture removal and shorter drying times than static tray drying. It does not sterilize the product or remove the need for binder, and its purpose is to reduce rather than increase moisture.

Question 20Pharmaceutics and Pharmaceutical Technology

A pharmacist compounds a prescription requiring 0.5 g of a drug per 100 mL of elixir. What quantity of drug is needed to prepare 250 mL of the elixir?

  1. 0.5 g
  2. 1.25 g Correct answer.
  3. 5 g
  4. 2.5 g

Explanation

The strength is 0.5 g per 100 mL, so 250 mL contains 2.5 times that amount, which is 1.25 g. Setting up the proportion 0.5 g divided by 100 mL equals x divided by 250 mL gives the same result. This is a straightforward ratio-proportion compounding calculation.

Question 21Pharmaceutics and Pharmaceutical Technology

Which combination of excipients and process conditions is most likely to cause a tablet to cap or laminate during compression?

  1. Addition of a glidant to improve die filling
  2. High compression speed with entrained air and insufficient binder Correct answer.
  3. Adequate binder level with slow compression speed
  4. Use of a superdisintegrant at a typical level

Explanation

Rapid compression traps air in the compact and, with weak interparticle bonding from insufficient binder, the tablet separates horizontally or as a cap when the punch withdraws. Slower compression and adequate binder allow air to escape and bonds to form. Glidants and superdisintegrants at normal levels are not causes of capping.

Question 22Pharmaceutics and Pharmaceutical Technology

A drug is to be formulated as a transdermal patch for systemic delivery. Which property is most essential for the drug to achieve useful flux across intact skin?

  1. Adequate lipophilicity balanced with some aqueous solubility Correct answer.
  2. Very high melting point
  3. Strong ionic charge at physiological pH
  4. High molecular weight above 1000 Da

Explanation

Effective transdermal permeation requires a molecule small enough to diffuse through the stratum corneum and lipophilic enough to partition into it while retaining enough aqueous solubility to enter the viable epidermis. Molecules above about 500 Da, strongly ionized compounds and high-melting solids permeate poorly. A balance of lipophilicity and aqueous solubility is therefore essential.

Question 23Pharmaceutics and Pharmaceutical Technology

In an aseptic filling facility, which practice best maintains the required environmental cleanliness during filling of a sterile ophthalmic product?

  1. Unidirectional laminar airflow over the critical filling zone with continuous environmental monitoring Correct answer.
  2. Use of non-sterile gloves by operators in the critical zone
  3. Periodic opening of the filling line to ambient air for inspection
  4. Routine foot traffic through the filling zone during operation

Explanation

Unidirectional airflow sweeps particles away from the critical zone, and continuous monitoring of particles and microbial counts verifies that the environment stays within limits. Unnecessary traffic, opening the line and non-sterile gloves all introduce contamination risk. Environmental control and monitoring together protect the sterile product.

Question 24Pharmaceutics and Pharmaceutical Technology

A poorly soluble weak base has a pKa of 8.5. In the fasted stomach at pH 1.5 it is fully ionized, yet it shows higher solubility there than in the small intestine at pH 6.8. Which explanation is most consistent with this observation?

  1. Gastric emptying has no effect on the extent of absorption
  2. The high hydrogen ion concentration in the stomach provides counter-ions that form soluble salts with the protonated base Correct answer.
  3. Ionized species are always more lipid soluble and are absorbed better in the stomach
  4. The drug is converted to a non-ionizable neutral molecule at pH 1.5

Explanation

A weak base is protonated at gastric pH and can form soluble chloride salts, which raises the apparent solubility despite ionization. Ionized species are generally less lipid soluble, so the first option is incorrect. The drug is not converted into a neutral molecule, and gastric emptying strongly influences the time available for dissolution and absorption.

Question 25Pharmaceutics and Pharmaceutical Technology

A hydrophilic matrix tablet shows a burst of drug release in the first hour followed by slow release. Which formulation change is most likely to reduce the initial burst while preserving sustained release?

  1. Applying a polymer-rich coating or increasing the initial polymer hydration rate Correct answer.
  2. Reducing the polymer content of the matrix
  3. Increasing the fraction of drug particles located at the tablet surface
  4. Adding a highly soluble sugar to the matrix

Explanation

A burst arises when surface drug dissolves before the gel layer forms, so a polymer-rich coat or faster polymer hydration creates the diffusion barrier sooner and suppresses early release. Reducing polymer content weakens the gel, and adding soluble sugar or increasing surface drug would worsen the burst. The change must strengthen the early barrier without abolishing sustained diffusion.

Question 26Pharmaceutics and Pharmaceutical Technology

In the design of a metered-dose inhaler, which property of the emitted aerosol is most directly controlled by the size of the suspended drug particles and the metering valve volume?

  1. The canister pressure
  2. The actuator orifice diameter
  3. The fine particle fraction Correct answer.
  4. The spray pattern width

Explanation

The fine particle fraction is the proportion of the emitted dose with an aerodynamic diameter small enough for pulmonary deposition, and it depends primarily on the primary drug particle size and the dose emitted per actuation, which is set by the metering valve volume. Canister pressure and orifice diameter influence plume velocity and droplet size from the propellant, not the solid particle fraction.

Question 27Pharmaceutics and Pharmaceutical Technology

Which statement best explains why a drug with a high hepatic extraction ratio has low oral bioavailability?

  1. The drug is extensively metabolized during its first pass through the liver. Correct answer.
  2. The drug is poorly absorbed from the gastrointestinal tract.
  3. The drug is rapidly excreted unchanged by the kidneys.
  4. The drug binds extensively to plasma proteins.

Explanation

A high hepatic extraction ratio means that a large fraction of the drug presented to the liver is removed during a single pass, so after oral absorption the drug undergoes extensive first-pass metabolism before reaching systemic circulation. This reduces oral bioavailability even when absorption is complete.

Question 28Pharmaceutics and Pharmaceutical Technology

A pharmacist needs to prepare 200 g of a 1% w/w hydrocortisone ointment from a 2.5% w/w hydrocortisone ointment and a plain ointment base. What mass of the 2.5% ointment is required?

  1. 50 g
  2. 100 g
  3. 20 g
  4. 80 g Correct answer.

Explanation

Using the alligation or dilution equation C1 × V1 = C2 × V2, the mass of 2.5% ointment needed is (1% × 200 g) / 2.5% = 80 g. The remaining 120 g is plain base.

Question 29Pharmaceutics and Pharmaceutical Technology

Which formulation strategy is most appropriate to stabilize a peptide drug against gastric acid and pepsin degradation after oral administration?

  1. Use of a superdisintegrant to accelerate tablet disintegration
  2. Addition of a chelating agent to the tablet core
  3. Enteric coating of a tablet core containing the peptide Correct answer.
  4. Incorporation of the peptide into a lipophilic suppository base

Explanation

An enteric coating resists dissolution in the acidic gastric environment and dissolves at the higher pH of the intestine, thereby protecting acid-labile peptide drugs from gastric acid and pepsin. Chelating agents, suppository bases, and superdisintegrants do not prevent gastric degradation.

Question 30Pharmaceutics and Pharmaceutical Technology

A lipophilic drug is formulated as an oil-in-water emulsion for intravenous administration. Which property of the dispersed oil droplets most directly determines the clearance of the emulsion from the bloodstream?

  1. The oil-to-water phase volume ratio
  2. The viscosity of the continuous phase
  3. The droplet size and surface characteristics Correct answer.
  4. The zeta potential of the oil droplets

Explanation

After intravenous injection, oil droplets are removed from circulation primarily by the reticuloendothelial system, and the rate of uptake depends on droplet size and surface properties such as opsonin adsorption. Smaller droplets with less opsonin-promoting surfaces circulate longer.

Question 31Pharmacology and Pharmacotherapeutics

A patient with an acute attack of gout and normal renal function is prescribed colchicine. Which regimen best reflects its accepted role in acute gout and the main toxicity to monitor?

  1. Intravenous colchicine 4 mg as a single dose, watching for bone marrow suppression
  2. Prophylactic colchicine 0.6 mg twice daily for six months, watching mainly for hyperkalemia
  3. High-dose oral colchicine until pain resolves or vomiting occurs, watching mainly for hepatotoxicity
  4. Low-dose oral colchicine (about 1.2 mg then 0.6 mg one hour later), watching for diarrhea and myopathy Correct answer.

Explanation

Low-dose colchicine is as effective as high-dose regimens in acute gout and markedly reduces gastrointestinal toxicity, so the 1.2 mg loading dose followed by 0.6 mg after one hour is preferred. Diarrhea is the earliest sign of toxicity, and myopathy or neuropathy can occur, especially with renal impairment or statins. High-dose oral escalation is no longer recommended because it adds toxicity without added benefit.

Question 32Pharmacology and Pharmacotherapeutics

Which mechanism explains why low-dose aspirin is used for secondary prevention of atherothrombosis while higher analgesic doses can be less cardioprotective?

  1. Aspirin irreversibly acetylates platelet COX-1, and low doses spare vascular prostacyclin while higher doses inhibit it Correct answer.
  2. Aspirin reversibly blocks platelet COX-2, and higher doses lose selectivity for the platelet enzyme
  3. Aspirin inhibits vitamin K epoxide reductase, and low doses avoid bleeding by sparing clotting factors
  4. Aspirin activates platelet ADP receptors, and low doses produce a weaker but longer-lasting effect

Explanation

Aspirin acetylates serine residues in platelet COX-1 irreversibly, blocking thromboxane A2 production for the platelet lifespan because platelets cannot synthesize new enzyme. At low doses, presystemic platelet exposure is high while endothelial prostacyclin generation is relatively spared, which favors antithrombotic benefit. Higher doses also suppress vascular COX-2-derived prostacyclin, offsetting some of the antiplatelet effect.

Question 33Pharmacology and Pharmacotherapeutics

A patient starting isoniazid for tuberculosis develops peripheral neuropathy. Which intervention is most appropriate?

  1. Stop isoniazid permanently and switch to streptomycin
  2. Add folic acid supplementation
  3. Add thiamine supplementation
  4. Add pyridoxine (vitamin B6) supplementation Correct answer.

Explanation

Isoniazid interferes with pyridoxine metabolism, causing a functional vitamin B6 deficiency that produces peripheral neuropathy. Pyridoxine supplementation prevents and treats this neuropathy without interrupting effective tuberculosis therapy. Thiamine and folic acid address different deficiencies and do not correct isoniazid-induced neuropathy.

Question 34Pharmacology and Pharmacotherapeutics

Which adverse effect is most characteristic of amiodarone and requires long-term monitoring even when the patient feels well?

  1. Acute pancreatitis with hypercalcemia
  2. Severe hypertension with reflex tachycardia
  3. Pulmonary fibrosis with thyroid and hepatic dysfunction Correct answer.
  4. Aplastic anemia with hemorrhagic cystitis

Explanation

Amiodarone accumulates in lung, thyroid, liver, cornea, and skin tissue, so pulmonary toxicity, thyroid dysfunction, and hepatotoxicity are its signature long-term risks. Baseline and periodic monitoring of chest imaging, thyroid function, and liver enzymes is therefore required. The drug can also prolong the QT interval and interact with warfarin and digoxin.

Question 35Pharmacology and Pharmacotherapeutics

A patient with heart failure and reduced ejection fraction is stable on an ACE inhibitor, beta-blocker, and loop diuretic but remains symptomatic. Which addition has the strongest evidence for reducing cardiovascular death and heart failure hospitalization?

  1. A thiazolidinedione for glycemic control
  2. Verapamil in place of the beta-blocker
  3. Sacubitril/valsartan in place of the ACE inhibitor Correct answer.
  4. Digoxin as the primary mortality-reducing agent

Explanation

Sacubitril/valsartan, a neprilysin inhibitor combined with an angiotensin receptor blocker, reduced cardiovascular death and heart failure hospitalization compared with enalapril in reduced-ejection-fraction heart failure. When switching from an ACE inhibitor, a 36-hour washout is required to avoid angioedema from combined bradykinin effects. This makes it a preferred replacement rather than an add-on to the ACE inhibitor.

Question 36Pharmacology and Pharmacotherapeutics

Which pharmacokinetic property most explains why gentamicin requires dosing-interval adjustment in renal impairment?

  1. It is eliminated almost entirely unchanged by glomerular filtration Correct answer.
  2. It undergoes extensive enterohepatic recirculation
  3. It is metabolized extensively by hepatic CYP3A4
  4. It is highly protein bound and displaced by bilirubin

Explanation

Aminoglycosides such as gentamicin are polar compounds cleared almost entirely by renal glomerular filtration without significant metabolism. When creatinine clearance falls, the drug accumulates and the risk of nephrotoxicity and ototoxicity rises, so doses and intervals must be adjusted. Therapeutic drug monitoring of peak and trough concentrations is standard practice.

Question 37Pharmacology and Pharmacotherapeutics

A patient on warfarin has an INR of 8.5 without bleeding. Which management is most appropriate?

  1. Give fresh frozen plasma immediately regardless of bleeding
  2. Start heparin infusion without interrupting warfarin
  3. Continue the same warfarin dose and recheck in one month
  4. Hold warfarin and give oral vitamin K, then recheck the INR Correct answer.

Explanation

For a markedly elevated INR without bleeding, warfarin should be withheld and low-dose oral vitamin K given, with INR rechecking to guide further dosing. Coagulation factor replacement is reserved for serious bleeding or very high INR with high bleeding risk. Simply continuing the same dose risks hemorrhage, and heparin does not reverse warfarin's effect.

Question 38Pharmacology and Pharmacotherapeutics

Which statement correctly describes the mechanism of metformin in type 2 diabetes?

  1. It closes pancreatic beta-cell ATP-sensitive potassium channels to release insulin
  2. It inhibits intestinal alpha-glucosidase to slow carbohydrate absorption
  3. It activates peroxisome proliferator-activated receptor gamma to increase insulin sensitivity
  4. It reduces hepatic gluconeogenesis and improves peripheral insulin sensitivity without stimulating insulin secretion Correct answer.

Explanation

Metformin decreases hepatic glucose production and improves insulin sensitivity, and it does not provoke hypoglycemia when used alone because it does not stimulate insulin release. Gastrointestinal upset is common and lactic acidosis is a rare but serious risk in severe renal impairment. These properties make it a usual first-line agent in type 2 diabetes.

Question 39Pharmacology and Pharmacotherapeutics

A patient with an acute exacerbation of asthma is given repeated inhaled salbutamol but remains wheezy. Which adjunct is most appropriate to add for its anti-inflammatory and bronchodilator-sparing effect?

  1. Systemic corticosteroids Correct answer.
  2. Inhaled ipratropium as long-term monotherapy
  3. Oral propranolol
  4. Montelukast as the sole acute rescue agent

Explanation

Systemic corticosteroids are indicated early in moderate to severe asthma exacerbations because they reduce airway inflammation and prevent relapse, though their effect takes hours. They complement, rather than replace, inhaled short-acting beta-2 agonists for rapid bronchodilation. Ipratropium may be added in severe cases but is not a long-term monotherapy.

Question 40Pharmacology and Pharmacotherapeutics

Which laboratory abnormality is the most specific early marker of digoxin toxicity?

  1. Hyperkalemia in the setting of acute overdose Correct answer.
  2. Hypocalcemia with prolonged QT
  3. Hypernatremia with hyperchloremia
  4. Hypokalemia with metabolic alkalosis

Explanation

Acute digoxin toxicity causes hyperkalemia because the drug inhibits the sodium-potassium ATPase, shifting potassium out of cells; the degree of hyperkalemia correlates with severity. Chronic toxicity is more often associated with hypokalemia, which itself potentiates digoxin effect. Serum digoxin concentration plus clinical and ECG findings guide management, and severe cases may need digoxin-specific antibody fragments.

Question 41Pharmacology and Pharmacotherapeutics

Which opioid effect is not readily reversed by naloxone at standard doses and may require ventilatory support?

  1. Fentanyl-induced respiratory depression
  2. Heroin-induced respiratory depression
  3. Buprenorphine-induced respiratory depression Correct answer.
  4. Morphine-induced respiratory depression

Explanation

Buprenorphine is a partial mu agonist with very high receptor affinity, so standard naloxone doses may be insufficient to displace it and higher or repeated doses, or ventilatory support, may be needed. Full agonists such as morphine, fentanyl, and heroin are readily reversed by naloxone because it competes effectively at the mu receptor. Naloxone's short half-life also means patients must be observed for renarcotization.

Question 42Pharmacology and Pharmacotherapeutics

A patient taking lithium develops coarse tremor, ataxia, and vomiting after starting a thiazide diuretic. Which mechanism best explains the toxicity?

  1. Thiazides inhibit renal lithium reabsorption, causing a paradoxical rise in serum levels
  2. Thiazides induce hepatic enzymes that convert lithium to a toxic metabolite
  3. Thiazides increase lithium protein binding and displace it into the brain
  4. Thiazides cause sodium depletion, increasing proximal tubular lithium reabsorption Correct answer.

Explanation

Lithium is handled like sodium in the proximal tubule, so when thiazides cause natriuresis and mild volume depletion, the kidney reabsorbs more lithium and serum levels rise. This can precipitate tremor, ataxia, vomiting, and seizures. Lithium levels and renal function should be monitored closely when diuretics, NSAIDs, or ACE inhibitors are added.

Question 43Pharmacology and Pharmacotherapeutics

Which antibiotic class acts by binding the 30S ribosomal subunit and is associated with photosensitivity and cartilage effects in children?

  1. Fluoroquinolones
  2. Tetracyclines Correct answer.
  3. Macrolides
  4. Penicillins

Explanation

Tetracyclines bind the 30S ribosomal subunit and block aminoacyl-tRNA attachment, and they cause photosensitivity and dental staining and are avoided in young children. They also chelate calcium and iron, so absorption is reduced by dairy and antacids. Fluoroquinolones also affect children's cartilage, but their target is DNA gyrase rather than the 30S subunit.

Question 44Pharmacology and Pharmacotherapeutics

A patient with a history of anaphylaxis to penicillin needs treatment for a serious infection. Which approach is most appropriate?

  1. Give oral amoxicillin at a reduced dose to test tolerance
  2. Give a cephalosporin with a shared side chain without allergy evaluation
  3. Use a structurally unrelated alternative such as vancomycin or aztreonam based on the organism, with allergy consultation Correct answer.
  4. Give penicillin with antihistamine pretreatment and no monitoring

Explanation

In a patient with a documented penicillin anaphylaxis, the safest approach is to select a structurally unrelated agent guided by the pathogen and, when needed, obtain allergy consultation. Aztreonam has minimal cross-reactivity with penicillins and is useful in beta-lactam allergy. Cephalosporins with identical side chains can cross-react and should not be used casually.

Question 45Pharmacology and Pharmacotherapeutics

Which antifungal agent requires monitoring for nephrotoxicity and is commonly used for serious systemic fungal infections, with infusion-related chills and fever as a notable effect?

  1. Terbinafine
  2. Fluconazole
  3. Nystatin
  4. Amphotericin B deoxycholate Correct answer.

Explanation

Amphotericin B binds ergosterol and forms pores in fungal membranes, but it also binds human cholesterol, causing infusion reactions and dose-limiting nephrotoxicity. Saline loading and monitoring of renal function and electrolytes help reduce renal injury. Lipid formulations are better tolerated in severe systemic disease.

Question 46Pharmacology and Pharmacotherapeutics

A woman of childbearing age is starting valproate for epilepsy. Which counseling point is most important?

  1. Valproate requires no monitoring because its levels are unaffected by other drugs
  2. Valproate is safe in pregnancy because it is not protein bound
  3. Valproate is highly teratogenic and should be avoided in pregnancy, with effective contraception and alternative therapy considered Correct answer.
  4. Valproate is preferred over lamotrigine in pregnancy for mood stabilization

Explanation

Valproate carries a high risk of neural tube defects and neurodevelopmental harm, so it should be avoided in women who may become pregnant unless alternatives fail. Effective contraception and preconception planning are essential, and lamotrigine or levetiracetam are often preferred. Valproate also inhibits hepatic enzymes and requires monitoring of levels and liver function.

Question 47Pharmacology and Pharmacotherapeutics

Which adverse effect is most characteristic of high-dose intravenous furosemide and warrants monitoring of hearing and electrolytes?

  1. Ototoxicity with hypokalemia and hypomagnesemia Correct answer.
  2. Hyperkalemia with metabolic acidosis
  3. Nephrogenic diabetes insipidus with hypernatremia
  4. Hyperuricemia with hyperkalemia and hypernatremia

Explanation

Loop diuretics inhibit the sodium-potassium-chloride cotransporter in the thick ascending limb, and rapid high-dose intravenous administration can cause ototoxicity, especially in renal impairment. They also cause hypokalemia, hypomagnesemia, and hypocalcemia through increased urinary losses. Electrolytes and hearing symptoms should be monitored.

Question 48Pharmacology and Pharmacotherapeutics

A patient with Parkinson disease on levodopa-carbidopa develops end-of-dose wearing off. Which strategy is most appropriate?

  1. Add a COMT inhibitor or MAO-B inhibitor to prolong dopaminergic effect Correct answer.
  2. Add a dopamine antagonist such as metoclopramide
  3. Increase carbidopa alone without changing levodopa
  4. Stop levodopa and start haloperidol

Explanation

Wearing off reflects declining dopaminergic effect at the end of each dose, and adding a COMT inhibitor or MAO-B inhibitor prolongs dopamine availability. Adjusting dose frequency or adding a dopamine agonist can also help. Dopamine antagonists worsen Parkinson symptoms and should be avoided.

Question 49Pharmacology and Pharmacotherapeutics

Which statement about the mechanism of selective serotonin reuptake inhibitors is correct?

  1. They block the serotonin transporter, and clinical benefit typically requires several weeks of treatment Correct answer.
  2. They inhibit monoamine oxidase and require a tyramine-free diet
  3. They block dopamine D2 receptors and are used mainly for psychosis
  4. They directly stimulate serotonin receptors and act within hours

Explanation

SSRIs inhibit the serotonin transporter (SERT), increasing synaptic serotonin, but the therapeutic response is delayed by several weeks because of downstream neuroplastic changes. They are not receptor agonists and do not require a tyramine-restricted diet. Abrupt discontinuation can cause a withdrawal syndrome.

Question 50Pharmacology and Pharmacotherapeutics

A patient taking simvastatin develops muscle pain with elevated creatine kinase after starting clarithromycin. Which mechanism best explains this interaction?

  1. Clarithromycin inhibits CYP3A4, increasing simvastatin exposure and myopathy risk Correct answer.
  2. Clarithromycin induces CYP3A4, lowering simvastatin levels and causing withdrawal
  3. Clarithromycin increases renal clearance of simvastatin, causing muscle injury
  4. Clarithromycin displaces simvastatin from plasma proteins, reducing its effect

Explanation

Simvastatin is metabolized by CYP3A4, and clarithromycin is a strong CYP3A4 inhibitor, so statin levels rise and myopathy or rhabdomyolysis can occur. Temporarily withholding the statin or choosing a non-CYP3A4 statin avoids the interaction. Gemfibrozil and high-dose niacin add further myopathy risk.