Distinguish between tachyphylaxis and tolerance.

• A. Tachyphylaxis is a rapid decrease in response after repeated exposure; tolerance is a slower, gradual decrease requiring higher doses for same effect.
• B. Tachyphylaxis is a gradual increase in response; tolerance is a rapid decrease.
• C. They are the same phenomenon.
• D. Tachyphylaxis occurs with antagonists only.

Answer: (A)