Most companies are familiar with filing for pediatric
indications. Since 1997, the opportunity
to obtain pediatric exclusivity has allowed companies to further differentiate
their products as well as gain an additional 6 months of protection against
generic competition. Pediatric dosing
makes excellent sense as drug metabolism in children differs from that of
adults thus increasing the risk of adverse reactions and lack of efficacy. Such differences are even observed across the
span of the pediatric age range. Without
specific dosing in the label, clinicians are playing guessing games with their
young patients.
When you take a careful look at the pediatric
situation with respect to the value of specific dosing, it is easy to see how
this parallels the geriatric field. While many
in the pediatric community warn that children should not be treated as little
adults, it could be also cautioned that the elderly should not be considered as
vigorous adults. Most clinicians feel
that it is absurd to treat an 8 year old in exactly the same manner as someone
who is 35; why should it not be just as illogical for a 75 year old to be
treated the same as a 35 year old? By
its nature, aging impacts the pharmacokinetics and pharmacodynamics of many
drugs. Reduced hepatic metabolism (as
low as 30-50%) secondary to changes in hepatic blood flow, liver mass and
hepatic endothelium, reduction in renal function and increased volume of
distribution of lipid soluble drugs all increase the elimination half-life of a
drug. Altered sensitivity, common to several
drug classes of drugs, results in accentuated effects in the elderly. Put together, this gives rise to an increase
in adverse events in this population. Accordingly, the medical community is
making due by practicing by the adage of “start low, go slow” and in general,
cutting the dose of many common medications in the elderly. Still, as these doses were not clinically
studied, it is not clear if as adverse events are attenuated the drug’s
efficacy is being jeopardized.
Why haven’t we heard more about geriatric exclusivity? Relative
to the overall medication use in the U.S, the elderly are a sizable
population. Although the 65 and older
age group comprises only 13% of the population, they account for approximately
34% of prescription medication use. [1,2]
Moreover a recent survey conducted by the CDC’s National Center for
Health Statistics reported that almost 90% of individuals 60 and older had used
at least one medication in the past month and 76% reported two or more. And the geriatric market is only going to grow
as the baby boomers age and the lifespan continues to extend. By the year 2030, the number of Americans 65
years of age and older is expected to grow to 71 million with those 85 years of
age and older representing the fastest growing segment of the population.
It would make logical sense that drugs used disproportionately by
the elderly would already have geriatric-specific dosing in their
labeling. This is not the case. Indeed,
in a study performed by Steinmetz, et al, looking at the 50 oral drugs most
commonly used by patients 65 and older in an in-patient setting, only 8 contained
some form of altered dosing guidance in the label specific to geriatric patients. None included age-specific dosing.
In researching circumstances in which geriatric exclusivity was
granted, our search yielded only one. In
2005, the FDA approved geriatric dosing for Savient Pharmaceuticals’ Oxandrin
(an anabolic steroid indicated for weight gain) and granted the product 3-year
marketing exclusivity. This is quite notable
given the exclusivity for adding pediatric dosing is limited to 6 months.
So goes the question of why companies are not pursuing geriatric
dosing as a way to attenuate competitive threat, both branded and generic. Unmistakably,
this pursuit does not make for a “clean” trial as the elderly are more likely
than their younger counterparts to have more comorbidities and thus be on other
multiple medications. This is most
likely why so few patients of 75 and older are included in clinical trials in
general, even for drugs that are very appropriate to them.
The opportunity for industry is substantial. In addition to the potential for an extra 3
years of exclusivity, providing specific dosing guidance for geriatric patients
will likely result in providers using that particular drug over competitors or
even generics. They may feel confident
that they can circumvent adverse events while maintaining the optimal level of
efficacy. What are your thoughts about
geriatric exclusivity and why it is not being utilized by life science
companies?
1.
Ferrini A, Ferrini R. 2000. Health in the Later Years. 3rd edition.
Boston, MA, McGraw Hill.
2. Centers for Disease Control and Prevention and
The Merck Company Foundation. “The State of Health and Aging in America 2004”.
Melissa Hammond, MSN, GNP is Managing Director at Snowfish and a Geriatric specialist.
