Clinical Trials and Miscellaneous MCQs

The standard margin of safety (SMS) is a measure of how much safer a drug's effective dose is compared to its toxic dose. It's calculated using the formula: SMS = (LD1 / ED99) - 1 * 100 In this case: Effective dose (ED99): The dose at which the medication causes improvement in bradykinesia and cogwheel rigidity in 99% of patients is 10 mg. Toxic dose (LD1): The dose that causes seizures in 1% of the population treated with this medication is 100 mg. Now, calculate the SMS: SMS = (100 mg / 10 mg) - 1 * 100 = 10 - 1 * 100 = 900 So, the standard margin of safety for this medication is 900. The correct answer is D) 900. This indicates that the medication is 900 times safer at the effective dose (10 mg) than it is toxic at the dose that causes seizures (100 mg). Reference: Basic & Clinical Pharmacology by Bertram G. Katzung Fourteenth Edition Pg no. 37

(A) The additive effects of drugs occur when two drugs with the same effect are added together and produce an effect that is equal in magnitude to the sum of the effects when the two drugs are given individually. (B) Neutralization occurs when two drugs combine with another to form an inactive compound. (C) Potentiation occurs if a drug lacking an effect of its own increases the effect of a second active drug. (D) Synergism occurs if two drugs with the same effect, when given together, produce an effect that is in greater magnitude than the sum of the effects when the drugs are given individually. Reference: Basic & Clinical Pharmacology by Bertram G. Katzung Fourteenth Edition Pg no.9

Adverse drug reactions can be defined as one of the two types: Type A: Dose dependent common extension of known pharmacological effect Type B: Dose independent uncommon symptoms and signs of drug allergy The most important type to the adverse drug reaction is type B, which encompasses both anaphylactic and anaphylactoid reactions. Reference: Physics, Pharmacology and Physiology for Anaesthetists, Matthew E. Cross, second edition, pg 151.