Select the appropriate diagnostic code using an ICD-9-CM code book for the diagnostic statements given in the following questions

Consumers in the United States must show a government ID before purchasing which OTC product?

A) Chlorpheniramine B) Phenylephrine C) Pseudoephedrine D) Xylometazoline

A maintenance dose of drug is given to

a. achieve an initial high drug concentration. b. keep blood concentration in the therapeutic range. c. allow the drug concentration to drop to 50% of its initial concentration. d. achieve a maximal response.