Question

A migraine sufferer took Two 400mg doses of naproxen. The half-life for

this drug is 90 min. How much is left in her body after 9 hours?

Answer 1

If y(t) is the mass (in mg) remaining after t years, then y(t) = y(0) (0.5)^{t/T} = 400 (0.5)^{t /4}, where T is the half-life period and y(0) is the amount at t = 0 years (initial).

Then at t = 20:

y(20) = 400 (0.5)^{20 /4} = \text{12.5 mg}

Explanation: