Thursday, April 9, 2009

Introductory viva to some Pharmacological terms

Q: 1. What do you mean by placebo?
Ans. It is an inactive compound used for the patient’s satisfaction about the use of drug for the treatment of a (particular) disease.

Q: 2. What do you mean by loading dose (LD)?
Ans. It is the amount of dose of a drug that will produce the required therapeutic effect by increasing the concentration of drug in plasma upto target concentration.

Q: 3. What is the formula for calculating the loading dose?
Ans. It is calculated by LD = Vd x TC
Where,
Vd = Volume of distribution
TC = Target concentration

Q: 4. What do you know about volume of distribution?
Ans. It is also known as “Apparent volume of distribution”. It is the volume of the fluid through which the drug is normally distributed in the body.
It can be calculated by
Vd = Total amount of drug in the body / Drug plasma concentration
= D / Co

Q: 5. What is the meaning of high value of volume of distribution?
Ans. It shows the high lipophilicity.

Q: 6. What are the formulae for the calculating the dosage for children?
Ans.
Young’s formula:
Child dose = Adult dose x Age in years / Age + 12
Dilling’s formula:
Child dose = Adult dose x Age in years / 20
Clark’s formula:
Child dose = Adult dose x Weight in pounds / 150

Q: 7. What are the different factors important in Drug distribution?
Ans.
1) Physical and Chemical characteristics of drug
a)                                       Molecular weight
          Ionization
2) Capillary permeability
3) Blood flow
4) Binding of drugs to plasma proteins
5) Tissue affinity

Q: 8. What do you mean by partial agonist and give example?
Ans. A partial agonist is that which activates a cell receptor, but does not produce as much of a physiological activity as does a natural full agonist e.g. pindolol at beta-adrenoceptors.

Q: 9. What do you know about inverse agonists and give example?
Ans. An inverse agonist binds to the receptors and produces opposite effects to those of agonists e.g. beta-carbolines on benzodiazepine receptors.

Q: 10. What is the difference between antagonist and inverse agonist?
Ans. Antagonists bind to the receptors without activating the receptors whereas inverse agonists bind to the receptors and produce exactly opposite effects to those of agonists.

Q: 11. What are the different types of antagonists?
Ans.
1) Pharmacological antagonist:
That antagonist which bind to receptors and stop the agonists from interacting with receptors to cause an activity.
2) Physiological antagonist:
The drugs, when act on different receptors and produce exactly opposite effects from one another, are said to be physiological antagonist.
3) Chemical antagonist:
Two drugs when combine with one another form an inactive compound and in the whole process no receptors are involved.

Q: 12. Give an example of Physiological antagonist.
Ans. Drugs acting on adrenergic receptors and cholinergic receptors are physiological antagonists.

Q: 13. Give an example of Chemical antagonist.
Ans. Protamine and Heparin.

Q: 14. What do you mean by synergistic effect?
Ans. It is a biological response to exposure to two or more than two drugs, which is more than the sum of the effects of the individual drugs. (can be symbolized as 1+1 = 3)

Q: 15. What do you know about potentiation?
Ans. A drug that normally lacks any effect of its own will increase the effect of another drug. (can be symbolized as 0 + 2 = 3)

Q: 16. What do you know about therapeutic index (TI)?
Ans. It is the ratio of median lethal dose of a drug to its median effective dose:
Therapeutic index = Median lethal dose/Median effective dose.
TI = LD50/ED50
Where,
median = the value or amount below which 50 % of the cases fall

Viva From Out of course of Pharmacology (Memorise the Surah Number, Ayah Number and What the Ayah wants to tell):

Q: 17. What ALLAH has said about hardwork in Holy Qur'an?
Ans: ALLAH has mentioned in Holy Qur'an:
" For truly with hardship comes ease; (5) truly with hardship comes ease. (6) Therefore, when thou art free (from thine immediate task), still labour hard, (7) And to thy Lord turn (all) thy attention. (8)
(Surah Al-Sharh or Al-Inshirah (The Expansion of the Breast), Surah # 94: Ayah # 5-8)"
Q: 18. What ALLAH has said about raising voices?
Ans. ALLAH has mentioned in Holy Qur'an:
"(Luqman said to his son,) ‘Be moderate in your tread and lower your voice. The most hateful of voices is the donkey’s bray.’ (19)
(Surah Luqman (Luqman), Surah # 31: Ayah # 19)"
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