Tips on Days’ Supply Calculations for Foam Products

PAAS National® receives many questions about topical prescriptions, including more complicated products like foam dosage form medications. These products often come in pressurized aluminum cans without a clear way of measuring the product when dispensing. In addition to this issue, prescribers often send prescriptions to the pharmacy with a vague set of instructions. PBMs are looking for a calculable set of instructions, regardless of how difficult it is to measure the product being dispensed. As frustrating as this is, PBMs require a true estimate of the days’ supply to ensure appropriate copays and refill intervals. Prescriptions written for, “Apply to the affected area,” do not provide enough information. Pharmacy staff should be diligent in recognizing when a prescription was sent without a clear way to calculate a days’ supply. This should be a red flag that the prescription requires additional clarification.

PAAS recommends…

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clarifying the directions with the prescriber’s office, documenting with a clinical note, and updating the patient’s label to reflect the clarification. The following are some questions to consider that may help when communicating with the prescriber and counseling your patients.

#1: Does the product come in a metered dose delivery system?

The medication packaged in a metered dose bottle will deliver a specific amount of product per pump actuation. Diclofenac sodium topical solution is an example of this type of product. According to the package insert, each pump actuation delivers 20 mg of diclofenac sodium in 1 g of solution. The usual dosage is to apply two pump actuations to the affected knee(s) two times a day. If the pharmacy receives a prescription with standard dosing to be used on both knees, the days’ supply would be calculated to 14 days for one 112 g bottle.

#2: Does the product come with an applicator?

Proctofoam® comes in an aerosol container that includes a special anal applicator. The package insert states the container will deliver a minimum of 14 applications. It would be recommended to clarify how many applicatorfuls are being applied daily. Standard directions are to apply to the affected area three to four times daily; therefore, the days’ supply would be calculated to 3.5 days for one 10 g container.  

#3: Does the product have recommended dosage information?

Dosage and administration information for the prescribed medication may help determine the maximum amount of product that should be used over a period of time or how many consecutive days the product may be used. For example, Enstilar® package insert states the patient should not use more than 60 g every four days and may be applied once daily for up to four weeks. If the directions on the prescription exceed these limitations, there may be DUR rejections due to third-party payor safety edits.

#4: Does the product have additional information in the instructions for use?

Clobetasol Propionate foam states the amount of foam being applied should be no more than 1.5 capfuls, about the size of a golf ball in the patient’s instructions for use. The dosage and administration section states patients should not use greater than 50 g per week or more than 21 capfuls per week.

PAAS Tips:

  • Clarify vague, noncalculable sets of instructions with a full clinical note, including:
    • Date/Time of the call/conversation
    • Name and title of who you spoke with
    • Specific details about the clarification
    • Initials or name of the pharmacy employee making the clarification  
  • Update the patient’s label to reflect clarifications
  • Educate staff on recognizing incomplete instructions prior to filling
  • Avoid including topical products on med sync
  • See July 2024 Newsline article, 2024 Self-Audit Series #5: Topical Prescriptions for more guidance on topical prescriptions
  • Download and share with staff the PAAS National® Topical Creams and Ointments Chart and utilize the PAAS National® App when utilizing the Finger-Tip Unit method

Lindsay Doebert, CPhT
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