In 1998, Medicaid programs in these 45 States paid for over 19 million prescriptions for antidepressants. Exhibit VI-13 shows the market share in Medicaid for each class of antidepressant in 1998. The selective serotonin reuptake inhibitors (SSRIs) citalopram, fluoxetine, fluvoxamine, paroxetine, and sertraline comprised 48% of total antidepressant prescriptions in 1998. Prescriptions for the three leading agents (fluoxetine, paroxetine, and sertraline) were nearly equal with approximately 3 million prescriptions each, or a 15-16% share each. Tricyclic antidepressants accounted for 27% of total prescriptions, or approximately 5 million prescriptions. Trazodone, with 2.2 million prescriptions in 1998, took 12% of the market. The four other new generation antidepressants (bupropion, mirtazapine, nefazadone, and venlafaxine) together accounted for 14% of prescriptions or approximately 2.7 million prescriptions. In total, new generation antidepressants accounted for over 62% of all prescriptions in Medicaid in 1998.
In dollar terms, these 19 million prescriptions corresponded to expenditures of nearly 1 billion dollars ($985 million). As seen in Exhibit VI-14, fluoxetine, while comprising only 15% of all Medicaid antidepressant prescriptions, accounted for 30% ($288 million) of all Medicaid spending for antidepressants in 1998 -- the highest among all antidepressants. The cost of fluoxetine is far greater than one would expect by making market share comparisons to similar agents. For example, sertraline accounted for more prescriptions in 1998 than fluoxetine, but spending for sertraline reached only $214 million (23% of all Medicaid dollars reimbursed for antidepressants in 1998). Similarly, dollars spent on paroxetine comprised only $199 million (20% of all Medicaid dollars spent on antidepressants in 1998) while the number of prescriptions was roughly equal to that of fluoxetine. Together, fluoxetine, sertraline and paroxetine comprised over 70% of all Medicaid spending on antidepressant drugs in 1998 ($711 million). While TCAs made up one-quarter of all prescriptions in 1998, they accounted for only 5% of all Medicaid dollars reimbursed for antidepressants ($54 million). The other new antidepressants bupropion, venlafaxine, nefazadone, and mirtazapine together accounted for expenditures of approximately $173 million or 18% of total expenditures, while capturing 14% of total prescriptions.
The data in Exhibits VI-13 and VI-14 are depicted in tabular form in Exhibit VI-15.