Question

Allopurinol 20 mg/mL Cherry Syrup 60 mL Methyl-cellulose

Suspension ad 120 mL Sig. Take one teaspoonful daily in AM. Having
no Allopurinol powder, the pharmacist used eight 300-mg tablets of
Allopurin

Answer 1

The pharmacist's use of eight 300-mg Allopurinol tablets is correct for compounding a 120 mL suspension at 20 mg/mL, resulting in the required total of 2400 mg of Allopurinol.

Step-by-step explanation:

To determine if the pharmacist's use of eight 300-mg Allopurinol tablets is correct when compounding a prescription lacking Allopurinol powder, we must calculate the total amount of Allopurinol required for the preparation. The prescription calls for a concentration of 20 mg/mL in a 120 mL suspension. Thus, the total amount of Allopurinol needed is 20 mg/mL × 120 mL, which equals 2400 mg.

The eight 300-mg tablets used by the pharmacist provide a total of 300 mg/tablet × 8 tablets, which equals 2400 mg. Therefore, the pharmacist has used the correct amount of Allopurinol to achieve the desired concentration in the suspension. Allopurinol is a competitive inhibitor of the enzyme xanthine oxidase, which is used in the treatment of conditions such as gout, where it prevents the formation of uric acid by competitively inhibiting the enzyme due to its structural similarity to the enzyme's natural substrate, hypoxanthine.