Based on an Interview with Lon Castle, MD
Director of Medical Policy and Clinical Quality for Medco

Drug trends — the annual rate of change in spending on prescription drugs from year to year — are “driven by physicians,” according to Lon Castle, MD, director of Medical Policy and Clinical Quality for Medco, the largest pharmacy benefit management company in the country, and contributing author of “2006 Drug Trend Report,” which is based on drug use among more than 55 million Medco members. The company processes 550 million prescriptions annually. The report shows that overall growth in prescription drug spending was 5.4% in 2005, the lowest growth rate recorded since 1999 (19%).

This decline was largely the result of deceleration in the overall growth rate for drug use, as well as declines in high-use drug categories and patients’ increasing acceptance and use of lower-cost generic drugs. Prescription drug use grew by only 2.7%, half the rate of increase reported in 2004. Unit costs also grew by only 2.7%, compared with 3.1% in 2004, driven by patients moving to lower-cost drug alternatives.

“What this demonstrates is that physicians monitor safety and efficacy issues, as well as the medical literature, very carefully,” Dr Castle, who practiced primary care for 10 years, tells IMWR. “It’s because physicians read the literature and then adjust their practice habits accordingly. That’s what drives trends like this.”

But certain drug categories accelerated. Dr Castle notes a more than 10% increase in treatment rates for antiplatelet drugs, which he attributes to more patients taking these drugs, primarily clopidogrel (Plavix).

“Same thing for the lipid-lowering category,” he says. “The utilization growth for cholesterol drugs was 9.8% last year. Our entire book of business only went up 2.7%. A 9.8% use rate in one single group is enormous. Cholesterol drugs are the single largest driver of trend.” 

Prescription drug use rates vary greatly across the country, as shown in the Figure.

New Biologics
A trend that is expected to continue, according to Dr Castle, is the expansion of new indications for already approved drugs, especially biologic agents. “Last year was the third lowest approval rate for biologics and new molecular entities in the past 25 years, with 20 approved last year [versus] 36 the year before,” he says. “There’s about 100 new molecular entities and biologics in the pipeline for the next 3 years, so we’re probably going to see anywhere between 25 and 30 new drugs each year for the next 3 years, which puts it in the pretty low range. But we’re probably going to see about 50 new indications in the next 1 to 2 years for some of these drugs, about half of which may be specialty drugs.”

According to Dr Castle, since many of the new treatment options with these drugs may be described in the specialty literature first, primary care physicians may be at a slight disadvantage. “It might come to them a little bit slower than to the specialists,” he explains. “It probably won’t affect patient care much, but it may produce just a little bit of lag time between specialists and primary care physicians, which, as we know, isn’t good.”

The Generic Explosion
While approvals for new drugs have declined over the past few years, approvals for generic drugs have expanded considerably. Between 2002 and 2005, 57 first-time generics with previous-year sales in the United States that topped $125 million were brought to market. Last year alone, 15 new generics became available, including generic versions of fentanyl (Duragesic) patches, oxycodone (OxyContin), fexofenadine (Allegra), and azithromycin (Zithromax), which collectively accounted for nearly $6 billion in brand-name market sales in 2004.

Already approved this year are generic versions of alprazolam extended-release (Xanax XR), venlafaxine (Effexor), meloxicam (Mobic), simvastatin (Zocor), sertraline (Zoloft); and pravastatin (Pravachol), among others.

“Primary care physicians are probably just living this right now with the generic approval of Zocor,” Dr Castle says. “Patients pay less for generic drugs through their prescription benefits, so a lot of primary care physicians are going to be asked to write a lot of generic prescriptions—probably more and more over the next several years, with the new drugs coming off patent.”

According to Dr Castle, 2005 was the first year that Medco dispensed more generic drugs (51.5%) than brand-name drugs. “In 2007, you’re going to see the first of the sedative hypnotics, Ambien, coming off patent. Norvasc, a large antihypertensive drug, will also come off patent. And then the first migraine triptan, Imitrex, will come off patent. In 2008 you’ll see Advair Diskus coming off patent, and Fosamax will become generic.”

Patients have quickly moved over to lower-cost generic drugs, a Medco analysis of drug claims found, with total generic dispensing rates for fexofenadine (Allegra), leflunomide (Arava), glimepi-ride (Amaryl), and azithromycin (Zithromax) topping 87% within 30 days after these counterparts to the brand-name versions became available. In contrast, physicians are much more reticent about generics, as the analysis of physician prescriptions showed (see Chart, page 1, this issue).

Specialty Drugs
If specialty drugs were taken out of their specific categories and shown as a single category, they would be the largest contributor to drug trend, at 25.1%, according to Dr Castle. He postulates that over the next few years, as these drugs become more familiar, primary care physicians are going to become more involved with them and are going to face a lot of the challenges related to them, such as cost and coordination of care issues.

“These drugs often require home healthcare, injections, monitoring, and teaching patients how to do this stuff,” Dr Castle explains. “And all of that has to be coordinated. Over time, primary care physicians are going to get more involved in some of these coordination of care and cost issues related to specialty drugs, and that’s going to add an additional burden onto their practices.”

“Hot” Drugs
Between 2000 and 2004, according to a recent drug use analysis, the number of adults aged 20 to 44 years using sleep medications doubled, and the number of adolescents aged 10 to 19 years using sleep medications increased by 85%.

“These are big increases,” notes Dr Castle. “It’s hard to say that these are being overprescribed, because we know that insomnia isn’t treated in this country like it should be. It’s hard to tease out from our data whether this is appropriate or inappropriate, but it’s one of those areas where primary care physicians are going to be inundated with this more and more, particularly as the new sleep medications come out and there’s more direct-to-consumer advertising.”

Several ambulatory-use central nervous system agents are in the pipeline for insomnia and other conditions.

The same trend applies to attention-deficit/hyperactivity disorder (ADHD) treatments for adults, according to Dr Castle. From 2000 to 2005, the increase in the number of adults taking ADHD drugs was nearly twice that in children. “The question is, are these adults that probably should have been treated as children and weren’t, or are these people who lead busy lives and are multitasking more than they ever have and need something to help them focus? It’s hard to say.”

These are issues that the healthcare community will be grappling with over the next several years, and, according to Dr Castle, “the physician’s office is going to be the battleground.”

Personalized Healthcare
Dr Castle believes the medical field will undergo a dramatic change in the form of personalized healthcare. “It’s going to be in the next 5 to 10 years, and primary care physicians are going to be on the foreground of this as well,” he notes.

Physicians will be able to order tests for genetic markers of diseases, liver function enzymes to determine how they metabolize drugs, drug transporter activity—all of which are going to make drug treatment more precise and more personalized.

“This is something that primary care physicians are going to have to start worrying more about now, even though the tests won’t come until years in the future, because the technology is ahead of the scientific evidence, and they soon are going to get bombarded with questions before all the data are in. But it’s clear we’re going in this direction. In 10 years we’ll be there, but patients have the opportunity to think they’re there now.”

Although he calls this an “exciting time for medications and physicians, because it will allow you to more appropriately and precisely treat your patients,” Dr Castle warns that this could be a double-edged sword if physicians are not adequately prepared to meet the challenges that lie ahead.