(a) A manufacturer of a prescription drug with a wholesale acquisition cost of more than forty dollars ($40) for a course of therapy shall notify each purchaser described in Section 127675 if the increase in the wholesale acquisition cost of a prescription drug is more than 16 percent, including the proposed increase and the cumulative increases that occurred within the previous two calendar years prior to the current year. For purposes of this section, a “course of therapy” is defined as either of the following:

1. (1) The recommended daily dosage units of a prescription drug pursuant to its prescribing label as approved by the federal Food and Drug Administration for 30 days.
2. (2) The recommended daily dosage units of a prescription drug pursuant to its prescribing label as approved by the federal Food and Drug Administration for a normal course of treatment that is less than 30 days.

(c)

1. (1) The notice required by subdivision (a) shall include the date of the increase, the current wholesale acquisition cost of the prescription drug, and the dollar amount of the future increase in the wholesale acquisition cost of the prescription drug.
2. (2) The notice required by subdivision (a) shall include a statement regarding whether a change or improvement in the drug necessitates the price increase. If so, the manufacturer shall describe the change or improvement.