Question

A cough medicine contains 0.40% (w/v) dextromethorphan, a cough suppressant, and

1.2% (w/v)

guaifenisin, an expectorant.

How many

milligrams of each drug would you obtain from

3.5 tsp

of cough syrup?

(1 tsp = 4.93 mL)

Answer 1

3.5 tsp = 3.5 x 4.93 ml = 17.255 ml                ( since each tsp = 4.93 ml)

now amount of dextromethorphan = [( w/v) % /( 100) ] x volume of drug

                                    = ( 0.4/100) x 17.255

                                 = 0.069 g

                       = 0.069 x 1000 mg   = 69 mg              ( since each 1g = 1000 mg)

amount of guaifenisin = ( 1.2/100) x 17.255

                        = 0.20706 g

                  = 0.20706 x 1000 = 207 mg

Thus 3.5 tsp of syrup has 69 mg of dextromethorphan and 207 mg of guainfenish