Drug oversupply, or stockpiling, due to overlapping drug refills can cause unnecessary drug costs

Disease-modifying drugs that treat cystic fibrosis account for high costs in drug oversupply

March 30, 2023

If you have a chronic condition, your pharmacy may notify you advance of your prescription running out and refill your medication while you still have some medication supply on hand. Pharmacy benefit design typically allow most prescriptions to be refilled before the on-hand medication supply runs out. Refilling with supply on hand consistently, over time, can result in a substantial oversupply and applied to high-cost medications for chronic conditions, the costs add up quickly.

How does oversupply happen?

Members are typically able to refill medications once 75% of the on-hand supply from the most recent fill has run out, based on billed days’ supply. That means for a 28-day supply, refilling at day 22 is allowed using the “75% on-hand supply has been exhausted” rule.

Although refilling after 75% of on-hand supply may promote adherence, it can also permit excessive on-hand medication supply accumulation, aka. stockpiling. Four months of refilling a prescription one week early can lead to an entire month’s worth of extra medications.

Stockpiling results in increased payer and member costs due to additional member co-payments, payer expenditures, and waste if there is a drug therapy change.

This is less of a concern for medications that treat many chronic conditions. Many of them are dispensed as inexpensive generics. Many changes in drug therapy can be handled within the same prescription (taking two tablets instead of one; or cutting a tablet in half). 

But what about high-cost, specialty medications for chronic conditions? Like disease-modifying drugs for treating cystic fibrosis (DMDCF) that cost $25,000+ per month supply. These drugs contribute dramatically to the overall cost impact of accumulated on-hand supply.

Addressing oversupply takes one-on-one pharmacist intervention

A lot of variables determine whether a patient does or does not have an oversupply of a medication. For example:

  • A prescription interruption might have been filled with a patient’s previous oversupply.
  • A mail-order refill program might contact patient for a refill at the 75% point; it might set its contact point at 85% or 90%.
  • A person picking up a prescription from a pharmacy might wait until their days supply has nearly run out before refilling a prescription.

Prime set out to study the unnecessary drug costs connected to oversupply for a set of high cost drugs that treat cystic fibrosis.

The key to the study was individual contact from a pharmacist to a patient to precisely determine the personal level of oversupply.

Prime’s research study set out to assess a DMDCF stockpiling managed care pharmacists (MCP) intervention program impact in three ways:

  • Did it delay DMDCF prescription refills?
  • Did it reduce DMDCF oversupply?
  • Did it reduce DMDCF drug cost?

The answer to these questions is YES.

Narrowing in on the subjects for the study

Eligible members of the study were:

  • Commercially insured
  • Enrolled in the Prime’s HighTouchRx® high-cost drug management program, and
  • Had paid pharmacy claims across the preceding six-month period indicating stockpiling of DMDCF.

The DMDCF drugs included in the analysis: elexacaftor, ivacaftor, lumacaftor, tezacaftor, and any licensed combination products containing these ingredients.

Brand Name

Generic Name

Brand Company

 Annual WAC 

Kalydeco® (granules)




Kalydeco® (tablets)




Orkambi® (tablets)

Ivacaftor; Lumacaftor




Ivacaftor; Tezacaftor



Trikafta® (tablets)

Elexacaftor; Ivacaftor; Tezacaftor



Orkambi® (granules)

Ivacaftor; Lumacaftor



WAC = wholesale acquisition cost

HighTouchRx rules engine did much of the prep work, a program within the GuidedHealth clinical services

Prime’s rules engine identified cystic fibrosis cumulative oversupply opportunities. The rules engine estimated the potential savings associated with the opportunity. The patient information was provided to MCP. Prime’s MCP’s conducted outreach to the dispensing pharmacy asking for follow-up with the member to confirm on-hand supply and request refill delays as appropriate.

Savings were calculated for each successful intervention by calculating the average daily cost of therapy and multiplying this by the number of days between the anticipated refill date, based on refill history, and the actual refill date post-intervention. Savings for each successful intervention were summed to determine total savings associated with program.

Among 13.5 million eligible members for the period in which opportunities were identified and loaded, there were 1,669 unique DMDCF utilizers with $2.50 per member per month spend.

 67 (4.0%) of 1,669 DMDCF utilizers were identified as having a potential DMDCF medication oversupply (stockpile) of at least 28 days, and these cases were loaded into the web tool for review by an MCP.

  • 0 cases identified per 1,000,000 enrolled lives
  • 20 cases for which MCP outreach was performed resulted in a delay in DMDCF refilling.
  • 17 elexacaftor/tezacaftor/ivacaftor cases, 2 ivacaftor cases, 1 lumacaftor/ivacaftor case

Outreach by managed care pharmacists to pharmacies requested:

  • A review of member medication fill history and
  • Outreach to member to confirm on-hand supply to delay subsequent refills.

Managed care pharmacists performed interventions across a six-month period, from August 2022 through January 2023, as part of a broader high-cost drug management strategy. Cases were classified as successful when an on-hand oversupply is confirmed and the refill was successfully delayed from the anticipated refill date.

Successful cases resulted in total validated annual program savings of $614,635 with an average of $30,732 in savings per successful case.

Savings for the program added up quickly

$614,635 in client were averted among 20 members with medication stockpiles. One out of every 25 utilizers of disease-modifying drugs for cystic fibrosis were identified as having an apparent oversupply of medication. The oversupply involved a pattern of repeated filling at or near the time of 75% exhaustion of the on-hand supply from the most recent fill as allowed by the pharmacy benefit plan.

Encouraging prescribers and pharmacies to discuss medication stockpiling with patients may lead to fewer observed cases of long-term oversupply.

Providing MCPs with identified instances of oversupply, generated from pharmacy claims data, can assist in managing stockpiling.

All brand names are the property of their respective owners.

Read about day-to-day activities and events at AMCP.


Cystic Fibrosis Disease-Modifying Drug Therapy Identification and Management of Cumulative Drug Oversupply

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