Prescriptions which stipulate that a brand-name drug must be dispensed rather than a generic could be costing US patients around $1.2 billion a year, while the costs to the government could be as high as $7.7 billion, according to new research.

Patients are less likely to fill a prescription designated "dispense as written" - meaning that the drug dispensed must be the named brand drug and not a generic - even if the patient themselves has requested the designation, according to researchers at Harvard Medical School.

Their study looked at 5.6 million prescriptions written for more than 2 million patients over a one-month period, and found that nearly 5% were designated "dispense as written," with over 2.7% of the requirements being made by doctors and 2% at the request of patients. But nearly 12% of the patient-requested "dispense as written" prescriptions were never filled, compared to about 8% for prescriptions for chronic-disease medicine which did not stipulate a brand, say Dr William Shrank and his team, reporting their findings in the American Journal of Medicine.

The study also found that patients paid an average of $44.50 for their prescriptions for brand-name drugs for which a generic alternative was available, compared with around $18 for a generic prescription.

By substituting the generic alternative for each multi-source brand that was filled for each "dispense as written"-designated prescription, patients in the study could have reduced their charges by more than $1.7 million and their health plans could have reduced their costs by over $10.6 million during the one-month study period, the researchers estimate.

Moreover, for the 3.6 billion-plus prescriptions filed in the US every year - and assuming a similar rate of "dispense as written" requests nationwide for both uninsured patients and those covered by state, federal and commercial health plans - eliminating "dispense as written" opportunities could reduce patient charges by as much as $1.2 billion annually and cut health system costs by up to $7.7 billion, they add.

"Physicians and patients should be aware that 'dispense as written' designations not only increase costs to the patient but also adversely affect rates that patients purchase those prescriptions," say the authors, who note that requests for such designations are more likely to be made by specialists, older physicians and patients aged 55-74, groups which, they suggest, "may represent targets for educational outreach."

Such educational efforts should focus on initiation of chronic medications, because patients disproportionately fail to purchase these prescriptions when either physicians or patients make the request, they add. 

The researchers conclude that, while "advocates of 'dispense as written' may argue that providing physicians and patients with greater discretion offers greater choice, opportunities for communication and adherence to therapy, our results indicate that 'dispense as written' requests are associated with excess costs and that patients are less likely to fill [such] prescriptions."

Moreover, they note: "it is interesting to observe that physicians request 'dispense as written' frequently for single-source branded products, medications for which no generics could be automatically substituted. Physicians with a strong preference for branded medications may not be aware of whether a generic is available and may request the branded agent as a preventive measure. Alternatively, physicians may request the branded medication to ensure that pharmacists do not substitute a different medication in the class."