Question 1: Define a pure substance and explain its significance in pharmaceutical formulations.

Answer: A pure substance consists of only one type of particle with a fixed composition; in pharmaceuticals, purity ensures consistent dosage and safety.

Question 2: Describe one analytical method used to determine the purity of a drug sample.

Answer: Chromatography or spectrophotometry are commonly used methods to analyse the purity of drug samples.

Question 1: A pharmaceutical sample weighs 5.0 grams and contains 4.75 grams of the active ingredient. Calculate the percentage purity of the sample.

Answer: Percentage purity = (Mass of active ingredient / Total mass of sample) × 100 = (4.75 / 5.0) × 100 = 95%

Question 2: A solution contains 0.02 mol of a drug in 1 litre of solution. Calculate its concentration in mol/dm³.

Answer: Concentration = moles / volume = 0.02 mol / 1 dm³ = 0.02 mol/dm³

Question 1: Outline the steps involved in using chromatography to assess the purity of a pharmaceutical tablet.

Answer: Dissolve the tablet in a suitable solvent, load the solution onto a chromatography plate, develop the plate in a solvent, and compare the separated spots to standards. Safety includes wearing gloves and eye protection.

Question 1: A spectrophotometric analysis shows that a drug solution has an absorbance of 0.45 at a specific wavelength. The calibration curve indicates that an absorbance of 1.0 corresponds to a concentration of 0.1 mol/dm³. What is the concentration of the drug in the solution?

Answer: Concentration = (Absorbance / Calibration absorbance) × Calibration concentration = (0.45 / 1.0) × 0.1 mol/dm³ = 0.045 mol/dm³

Question 1: Explain why high purity levels are critical in the manufacturing of pharmaceuticals. Include potential risks of impurities and how they can affect patient health. (6 marks)

Answer: High purity levels in pharmaceuticals ensure that the medication delivers the correct dose without harmful contaminants. Impurities can cause adverse reactions, reduce drug effectiveness, and lead to toxicity. Strict quality control and analytical testing are essential to safeguard patient health.

Question 1: Describe how ensuring the purity of active pharmaceutical ingredients (APIs) influences the development of targeted drug delivery systems.

Answer: Ensuring API purity improves drug stability, reduces side effects, and allows for precise targeting of diseased cells, enhancing treatment efficacy.