Revise MBBS

Paper I — 2024 December (Supplementary) (2019 Scheme) — Q4

6 min read

Paper I
2024 December (Supplementary) (2019 Scheme) · 100 marks · 180 min

Question

Define bioavailability. What are the factors that affect bioavailability of drugs (1+5)

Q46 marksShort Essays

Answer

Bioavailability is the fraction (or percentage) of an administered dose of a drug that reaches the systemic circulation in an unchanged, active form. For an IV dose, bioavailability is 100% by definition; for other routes it is calculated by comparing the area under the plasma concentration-time curve (AUC) for that route against the AUC for an equal IV dose.

Factors affecting bioavailability:

  • First-pass (presystemic) metabolism — drugs absorbed from the GI tract pass through the liver via the portal circulation before reaching systemic circulation; extensive hepatic metabolism at this stage (e.g. propranolol, lignocaine) can drastically reduce oral bioavailability compared to parenteral routes.
  • Drug formulation — particle size, disintegration and dissolution rate, and the specific salt/ester form all affect how much drug is actually absorbed; poorly formulated tablets may pass through the gut without fully dissolving.
  • Physicochemical properties of the drug — lipid solubility, degree of ionization at gut pH, and molecular size all affect membrane permeability and absorption.
  • GI factors — gastric emptying rate, intestinal motility, presence of food (can enhance or reduce absorption depending on the drug), and gut pH all influence how much drug is absorbed before it is eliminated.
  • Route of administration — parenteral (especially IV) routes bypass first-pass metabolism and absorption barriers entirely, generally giving higher bioavailability than oral administration for drugs with significant first-pass loss.
  1. 1Pharmacokinetics

Other Years Asked

  1. 1Define plasma half-life and give two examples of drugs with very short half life. Define therapeutic index and give two examples each for drugs with high and low therapeutic index". (4+4)4. Classify drugs used to treat Parkinsonism with one example from each group2022 February (2019 Scheme)Short Essay · 10 marks
  2. 2Discuss the factors modifying drug action. Describe the clinical importance of plasma protein binding of drugs. (4+4)2024 June (Supplementary) (2019 Scheme)Short Essay · 8 marks
  3. 3Briefly describe kinetics of elimination. Add a note on factors modifying drug action. (4+4)2023 January (Supplementary) (2019 Scheme)Short Essay · 8 marks
  4. 4Briefly describe drug biotransformation. Describe microsomal enzyme induction. (4+4)2023 July (Supplementary) (2019 Scheme)Short Essay · 8 marks
  5. 5Briefly describe kinetics of elimination.2025 March (Supplementary (SAY)) (2019 Scheme)Short Answer · 4 marks
  6. 6Briefly describe enzyme induction and enzyme inhibition with suitable examples.2024 March (Supplementary) (2019 Scheme)Short Answer · 4 marks
  7. 7Contra indications and drug interactions of oral contraceptive pills.2025 March (Supplementary (SAY)) (2019 Scheme)Short Answer · 4 marks
  8. 8Plasma half life2022 October (Supplementary) (2010 Scheme)Short Note · 3 marks
  9. 9First pass metabolism.2016 October (Supplementary) (2010 Scheme)Short Note · 3 marks
  10. 10Desferrioxamine2018 July (Supplementary) (2010 Scheme)Short Note · 3 marks
  11. 11Microsomal enzyme induction2013 September (Supplementary) (2010 Scheme)Short Note · 3 marks
  12. 12Plasma half life2018 February (2010 Scheme)Short Note · 3 marks
  13. 13Define half life of a drug and give its clinical significance2024 August (Supplementary) (2010 Scheme)Short Note · 3 marks
  14. 14Adverse effects of oral contraceptives2015 February (2010 Scheme)Short Note · 3 marks
  15. 15Plasma half-life2014 March (2010 Scheme)Short Note · 3 marks
  16. 16Bioavailability.2016 February (2010 Scheme)Short Note · 3 marks
  17. 17Apparent volume of distribution2019 February (2010 Scheme)Short Note · 3 marks
  18. 18First pass metabolism2019 July (Supplementary) (2010 Scheme)Short Note · 3 marks
  19. 19Kinetics of elimination2013 April (2010 Scheme)Short Note · 3 marks
  20. 20Pharmacogenetics2021 February (Supplementary) (2010 Scheme)Short Note · 3 marks
  21. 21Plasma half life2021 December (Supplementary) (2010 Scheme)Short Note · 3 marks
  22. 22Insulin Glargine2019 February (2010 Scheme)Short Note · 3 marks
  23. 23Dipivefrine2017 February (2010 Scheme)Short Answer · 1 mark
  24. 24Mention two differences between tetracycline and doxycycline2013 April (2010 Scheme)Short Answer · 1 mark
  25. 25Low dose ritonavir2018 July (Supplementary) (2010 Scheme)Short Answer · 1 mark
  26. 26Select the CORRECT statement regarding protein binding of drugs: 1. Protein bound drug is not available for action. 2. Highly plasma protein bound drugs tend to have high volume of distribution. 3. Highly protein bound drugs are generally long acting. 4. Basic drugs are generally bound to albumin.2024 December (Supplementary) (2019 Scheme)MCQ · 1 mark
  27. 27Assertion (A): Azathioprine dose is decreased with Allopurinol. Reason (R): Azathioprine and allopurinol cause bone marrow suppression.2025 March (Supplementary (SAY)) (2019 Scheme)MCQ (A/R) · 1 mark
  28. 28Enzyme inducers2014 March (2010 Scheme)Short Answer · 1 mark
  29. 29Imipenem with cilastatin2021 December (Supplementary) (2010 Scheme)Short Answer · 1 mark
  30. 30The following insulin is preferred to be given intravenously in diabetic ketoacidosis:2024 December (Supplementary) (2019 Scheme)MCQ · 1 mark
  31. 31Ritonavir in low doses in various Anti retroviral regimes2024 August (Supplementary) (2010 Scheme)Short Answer · 1 mark
  32. 32The Dopamine agonists used to treat Parkinson’s disease are:2025 March (Supplementary (SAY)) (2019 Scheme)MCQ (Multi) · 1 mark
  33. 33Plasma half life and its clinical relevance.2016 February (2010 Scheme)Short Answer · 1 mark
  34. 34The antihistaminic drug banned due to the deaths caused by Torsades de pointes is2025 March (Supplementary (SAY)) (2019 Scheme)MCQ · 1 mark
  35. 35Which of the following diuretics are used to treat hyperaldosteronism2025 March (Supplementary (SAY)) (2019 Scheme)MCQ (Multi) · 1 mark
  36. 36Oral anticoagulants2018 July (Supplementary) (2010 Scheme)Short Answer · 1 mark
  37. 37The following statements about iron kinetics is FALSE:2024 December (Supplementary) (2019 Scheme)MCQ · 1 mark
  38. 38Atracurium2018 February (2010 Scheme)Short Answer · 1 mark
  39. 39Causing peripheral neuritis2018 July (Supplementary) (2010 Scheme)Short Answer · 1 mark
  40. 40Comment on the drug interaction produced by sulfonylureas and salicylates.2013 September (Supplementary) (2010 Scheme)Short Answer · 1 mark
  41. 41Pro drugs2017 August (Supplementary) (2010 Scheme)Short Answer · 1 mark
  42. 42Chemical antagonism with one example.2014 September (Supplementary) (2010 Scheme)Short Answer · 1 mark
  43. 43The factor which does not govern the volume of distribution of a drug is2024 December (Supplementary) (2019 Scheme)MCQ · 1 mark
  44. 44Hofmann elimination2013 April (2010 Scheme)Short Answer · 1 mark
  45. 45The WRONGLY paired drug and its influence on thyroid function is:2024 December (Supplementary) (2019 Scheme)MCQ · 1 mark
  46. 46Imipenem and cilastatin2021 February (Supplementary) (2010 Scheme)Short Answer · 1 mark
  47. 47What is a pro drug and mention two examples2013 September (Supplementary) (2010 Scheme)Short Answer · 1 mark
  48. 48The drug safe in pregnancy2025 March (Supplementary (SAY)) (2019 Scheme)MCQ (Multi) · 1 mark
  49. 49Glipizide in elderly patients2022 May (Supplementary) (2010 Scheme)Short Answer · 0.3 marks
  50. 50Microsomal enzyme inducers2019 July (Supplementary) (2010 Scheme)Short Answer · 0.3 marks
  51. 51Anti-fungal azole derivative2021 December (Supplementary) (2010 Scheme)Short Answer · 0.3 marks
  52. 52Atypical neuroleptics2021 December (Supplementary) (2010 Scheme)Short Answer · 0.3 marks
  53. 53Prodrugs2022 October (Supplementary) (2010 Scheme)Short Answer · 0.3 marks
  54. 54Prodrugs.2025 March (Supplementary) (2010 Scheme)Short Answer · 0.3 marks
  55. 55 Liposomal Amphotericin B in Visceral leishmaniasis. Name the following (Two examples for each) (5x1=5)2024 March (Supplementary) (2010 Scheme)Short Answer · 0.3 marks
  56. 56HMG-CoA reductase inhibitor2019 February (2010 Scheme)Short Answer · 0.3 marks
  57. 57Drugs having high first pass metabolism2024 March (Supplementary) (2019 Scheme)Short Answer · 0.2 marks
  58. 58Microsomal enzyme inhibitors2023 January (Supplementary) (2019 Scheme)Short Answer · 0.2 marks
  59. 59Prodrugs.2023 July (Supplementary) (2019 Scheme)Short Answer · 0.2 marks

Graph View

Revise MBBS
Preview