The drug Valium is eliminated from the bloodstream exponentially with a half-life of 36 hours. Suppose that a patient receives an initial dose of 70 milligrams of Valium at midnight.

a. How much Valium is in the patient’s blood at noon on the first day?

b. Estimate when the Valium concentration will reach 35% of its initial level.

**Solution:-**

a. How much Valium in the patient’s blood at noon on the first day?

There is approximately 55.6 mg of Valium in the patient’s blood at noon on the first day.

b. Estimate when the Valium concentration will reach 35% of its initial level.

After approximately 55 hours the Valium concentration will reaches 35% of its initial level.