Sunday, May 06, 2001


From: Bryan R. Luce, Ph.D., MBA

Chief Executive Officer

MEDTAP International


Ya Chen Tina Shih, Ph.D.

Research Scientist

MEDTAP International


Subject: Statement Concerning Non-Sedating Antihistamines Moving to Over-The-Counter Status

Disclosure: My company, MEDTAP International, has conducted health economic research on contract with one or more of the pharmaceutical companies concerning second generation antihistamines and is presently consulting with same on the present OTC conversion issue. This statement is made on my own behalf.

Further, this statement is not a position statement. Rather it is intended to provide a technical review to the FDA and the Committee on a portion of the petition submitted by Blue Cross of California, specifically the summary study abstract entitled " Cost-Effectiveness of Converting Non-Sedating Antihistamines from Prescription to Over-The-Counter Status" by Nichol and Sullivan. In submitting our statement, we are aware that the FDA will not be considering health economic arguments in its decision process. However, we also understand that an important safety rationale by the petitioner is that OTC status of second generation antihistamines will increase availability of these drugs, which, in turn, will be expected to avoid unsafe consequences, specifically accidents, associated with first generation products. This projection is based, largely, on economic grounds. The Nicole, Sullivan abstract was submitted in support of the contention of increased safety due, primarily to increased availability of second generation products. Below we provide the Committee and the FDA the benefit of our review.



Given the available data and the decision at hand, a decision-analytic model is an ideal tool to assist the decision process and we recommend that the FDA utilize such a tool for decisions such as the present one. However, as noted below, we question whether the present submission is sufficiently refined and whether there is sufficient consensus of key assumptions to assist in the particular deliberation process at hand. In particular, we argue that some key assumptions are unreasonable.

The overall structure of the model seems appropriate.

Specific Mode Elements and Structure:

Model Assumptions:



A decision-analytic model is a useful and valid technique to estimate effectiveness, safety and cost-effectiveness impact of a Rx to OTC conversion of second generation antihistamines and the general approach used in the Nichol and Sullivan model seems correct. However, the model as presently specified seems to contain unreasonable assumptions, and a several technical problems, which call into question the usefulness of the findings. Specifically, we do not believe that the model as presently specified, is predictive of future demand following a hypothetical OTC conversion. The principle driving assumption which seems in error is an assumed 67% drop in price of second generation antihistamines which would lead to a predicted 3-fold increase in demand for these products. We believe, to the contrary, that a more likely scenario is that present users of second generation antihistamine users would face a large price increase which would actually decrease demand.