The optimal dose of an
antidepressant depends on the indication and on the patient. For SSRIs, SNRIs,
and a number of newer agents, the starting dose for the treatment of depression
is usually a therapeutic dose (Table 30–3). Patients who show little or no
benefit after at least 4 weeks of treatment may benefit from a higher dose even
though it has been difficult to show a clear advantage for higher doses with
SSRIs, SNRIs, and other newer antidepressants. The dose is generally titrated
to the maximum dosage recommended or to the highest dosage tolerated if the
patient is not responsive to lower doses. Some patients may ben-efit from doses
lower than the usual minimum recommended therapeutic dose. TCAs and MAOIs
typically require titration to a therapeutic dosage over several weeks. Dosing of
the TCAs may be guided by monitoring TCA serum levels.
Some anxiety disorders
may require higher doses of antidepres-sants than are used in the treatment of
major depression. For example, patients treated for OCD often require maximum
or somewhat higher than maximum recommended MDD doses to achieve optimal
benefits. Likewise, the minimum dose of parox-etine for the effective treatment
of panic disorder is higher than the minimum dose required for the effective
treatment of depression.
In the treatment of
pain disorders, modest doses of TCAs are often sufficient. For example, 25–50
mg/d of imipramine might be beneficial in the treatment of pain associated with
a neuropa-thy, but this would be a subtherapeutic dose in the treatment of MDD.
In contrast, SNRIs are usually prescribed in pain disorders at the same doses
used in the treatment of depression.