Total Prescriptions (TRx)

Key facts

Formula

New prescriptions (NRx) plus refills

Counted when

A prescription is dispensed, not when it is written

Common adjustment

Some data sources normalize counts to 30-day supply equivalents

Public Medicare analog

Total claims and 30-day fills in CMS Medicare Part D Prescribers data

What are total prescriptions?

Total prescriptions measure how many times a product was dispensed to patients in a given week, month or year. Each fill counts: the original fill of a prescription and each later refill both add to TRx.

Commercial TRx estimates are usually built from pharmacy dispensing records. Because no single source captures every pharmacy, many estimates are projected from a sample of pharmacies to national totals, then reported by product, strength, prescriber, geography and payer type.

TRx counts only prescriptions that were filled. Prescriptions that were written but never picked up, often called abandoned prescriptions, do not appear.

How TRx is calculated

The basic formula is TRx equals NRx plus refills, but data vendors differ on details that change the number:

Confirm the definition before comparing TRx figures from two sources or two time periods.

• Days supply: a 90-day fill may count as one prescription or be normalized to three 30-day equivalents.
• Channel coverage: retail, mail order, specialty and long-term care pharmacies may or may not be included.
• Transfers: a prescription moved to a new pharmacy may be counted as new or as a refill.
• Projection method: sample-based national estimates differ from counts of all claims in a closed data set.

Why TRx matters

TRx is the headline measure of a brand's size and trend. Market share is commonly expressed as TRx share within a drug class, field teams are often measured on TRx growth in their territories, and TRx trends show the speed of generic erosion after loss of exclusivity.

Because TRx includes refills from long-standing patients, it responds slowly to change. A brand losing new patients can show stable TRx for months, which is why analysts pair it with NRx and new-to-brand prescriptions (NBRx).

TRx in public Medicare data

The CMS Medicare Part D Prescribers files report total claims, which include refills, and 30-day fills, which standardize for days supply, by prescriber National Provider Identifier (NPI) and drug. They cover only Medicare Part D and are released with a lag, but they offer a free, prescriber-level view of volume.