Access and Utilization of New Antidepressant and Antipsychotic Medications. E. Comparison of Psychotherapeutic Utilization with Utilization of Other Drug Classes

01/01/2000

A primary concern of this study has been to determine whether newer psychotherapeutics are subject to more stringent utilization controls than are other classes of pharmaceuticals. In this section, we compare the utilization of psychotherapeutics with the utilization of other classes of pharmaceuticals that have seen the introduction of newer agents in recent years.

The new oral antidiabetic agents make constitute an excellent comparator group to psychotherapeutics for a number of reasons:

  • Diabetes represents a major cost center for health care payers, as does mental health;
  • Pharmacotherapy for diabetes and mental illness is always a long-term commitment;
  • New pharmacologic agents, representing new mechanisms of action, entered a therapeutic area dominated by generics; and
  • These new antidiabetic agents were introduced during the same time period as the atypical antipsychotics (1994-1997).

The oral antidiabetics included in this analysis are described in Exhibit VI-22, below.

Exhibit VI-22. Oral Antidiabetic Categories

Generic Name Examples and Brand Names Launch Date
Acarbose Precose® 1995
Glimepiride Amaryl® 1995
Glipizide (extended release) Glucotrol® XL 1994
Metformin Glucophage® 1995
Repaglinide Prandin® 4th quarter 1997
Troglitazone Rezulin® 1st quarter 1997
Generic Sulfonyl Ureas
(Representative) Acetohexamide
Chlorpropamide
Glipizide
Glyburide
Dymelor®
Diabinese®
Gluotrol®
DiaBeta®, Micronase®
Prior to 1995

Medicaid prescriptions for oral antidiabetic agents increased from 4.1 million in 1995 to 7.6 million in 1998, an increase of 82%. At the same time, expenditures for these agents increased nearly 3-fold, increasing from $114 million in 1995 to $311 million in 1998.

Proportionally, the increase in spending for oral antidiabetics was far smaller than the increase observed for the psychotherapeutic classes. Exhibit VI-23 shows the ratio between the percentage increase in expenditures and the percentage increase in total prescriptions between 1995 and 1998 for the three classes, antipsychotics, antidepressants, and oral antidiabetics. The results show that the ratio between the increase in expenditures and the increase in prescriptions is 8.0 for antipsychotics. (It should be remembered that clozapine prescriptions were relatively flat during this time, and therefore the increase in cost is largely attributable to other new agents.) For antidepressants this ratio is 2.4, whereas for oral antidiabetics this ratio is 2.1. These data show that the cost (in terms of pharmaceutical expenditures) of converting to newer agents is far greater for antipsychotics than it is for either antidepressants or oral antidiabetics. However, the cost for converting to newer antidepressants is only marginally greater than that for oral antidiabetics.

Exhibit VI-23. Comparison of Increase in Prescriptions and Expenditures for 3 Pharmaceutical Classes in Medicaid, 1995-1998

Class % Increase in
Prescriptions
% Increase in
Expenditures
Ratio
Antipsychotics 20% 160% 8.0
Antidepressants 40% 96% 2.4
Oral Antidiabetics 82% 172% 2.1

Source: HCFA(now known as CMS) Medicaid Drug Rebate Program Data, 1995-1998. 46 States reporting, 1995-1998, 45 States Reporting, 1998.


In spite of this difference in cost it appears that newer oral antidiabetics have replaced older agents only marginally faster than atypical antipsychotics have replaced traditional antipsychotics. In 1995, only 11% of all prescriptions for oral antidiabetics were for an agent other than a generic sulfonyl urea, by 1998, 55% of all prescriptions were for a newer agent. In contrast, whereas in 1995, only 16% of all antipsychotic prescriptions were for an atypical agent, in 1998, 51% of antipsychotic prescriptions were for an atypical antipsychotic.