Which combination medication is derived from natural and synthetic sources?

• A. Anistreplase
• B. Recombinant DNA
• C. Vaccines
• D. Fentanyl

Answer: (A)

This item tests how a drug can come from both natural sources and synthetic modification. Anistreplase is a thrombolytic formed as a complex of streptokinase, produced by streptococcal bacteria (natural), and plasminogen, a human protein (natural). It is then acetylated with synthetic groups to prolong its half-life and activity, creating a prodrug that behaves as a single medication. That combination of natural components with chemical modification is what makes it a product derived from both natural and synthetic sources.

Fentanyl is entirely synthetic, with no natural-derived component. Recombinant DNA products arise from genetic engineering rather than mixing natural components with chemical modification. Vaccines can involve natural antigens and synthetic additives or modified components, but they do not embody the same clear natural-plus-synthetic combination as anisoylated streptokinase-plasminogen.