Antidepressants (cont.)
TCAs may
increase the blood pressure elevating effect of epinephrine, norepinephrine,
dopamine, phenylephrine, and dobutamine.
Cimetidine (Tagamet) may reduce the
breakdown of some TCAs, for example, amitriptyline (Elavil, Endep), increasing the
level of the TCA in the body and potentially leading to increased side effects.
As mentioned previously, TCAs should not be combined with MAOIs.
TCAs are associated with a number of cardiovascular
(heart and blood vessels) effects such as orthostatic hypotension and abnormal
heart rates and rhythms. Orthostatic hypotension may lead to dizziness, falls,
and fractures. Orthostatic hypotension may be managed by reducing or
discontinuing the TCA dose, increasing salt intake, or treatment with steroids.
If abnormal heart rhythms develop, TCAs should be discontinued. TCAs are not a
good choice for patients with cardiovascular conditions.
TCAs have
anticholinergic effects which manifests as dry mouth, constipation, urinary
hesitation, sexual dysfunction, increased heart rate, and visual disturbance.
Desipramine (Norpramin)
and nortriptyline (Pamelor) cause less anticholinergic effects than other TCAs.
- Sugarless gum or candy, or
pilocarpine (Salagen) oral rinse may alleviate dry mouth;
- constipation may be reduced by bulk laxatives and increased hydration;
- urinary
hesitation may be treated with bethanechol; and
- visual disturbance may be
treated with pilocarpine eye drops.
Sexual dysfunction may be managed with sidenafil (Viagra), reducing the TCA dose or discontinuing the TCA. Yohimbine,
ginkgo, bethanechol, and neostigmine have also been used for managing TCA
induced sexual dysfunction.
TCAs should be avoided by individuals with prostatic
hypertrophy, cognitive impairment, or narrow-angle glaucoma because drugs with anticholinergic side effects can worsen
symptoms of these conditions.
TCAs also cause sedation. Amitriptyline (Elavil, Endep), doxepin (Sinequan),
and trimipramine (Surmontil) are more sedating than amoxapine and desipramine (Norpramin). Sedation may
improve after a few weeks of treatment. Sedating TCAs may be beneficial for
depressed patients who have insomnia.
Dose dependant and reversible weight gain
may occur during TCA treatment. Amitriptyline (Elavil, Endep)
causes weight gain more often than
desipramine (Norpramin).
What are examples of TCAs?
What are selective serotonin reuptake inhibitors (SSRIs)?
SSRIs were developed after TCAs and are the most widely used class of
antidepressants. They work by increasing the level of serotonin in the brain.
Unlike MAOIs and TCAs, they do not significantly affect norepinephrine levels
in the brain. SSRIs also have fewer and milder side effects, fewer drug
interactions, and are much less likely to be effective for committing suicide
than TCAs.
Confusion, high blood pressure, tremor, hyperactivity,
coma, and death may occur when SSRIs are combined with drugs that increase brain
serotonin levels, for example, MAOIs, TCAs, sumatriptan (Imitrex), linezolid
(Zyvox), St John's Wort, tramadol (Ultram), and meperidine (Demerol).
The risk
of gastrointestinal bleeding may be increased when SSRIs are combined with
nonsteroidal antiinflammatory drugs (NSAIDs).
SSRIs may increase the effect of
warfarin
(Coumadin), leading to excessive bleeding. Therefore, warfarin therapy should be
monitored more frequently in patients who are also taking SSRIs.
SSRIs cause headaches and dose-related nausea, vomiting,
and diarrhea that
improve with continued treatment.
Insomnia, restlessness, and agitation-which
decrease over time-also are associated with SSRIs. Insomnia can be treated with
low dose (50-100 mg) trazodone
(Desyrel) at bedtime and agitation may be managed by
reducing the SSRI dose or treating
with anti-anxiety drugs.
SSRIs also are associated with sexual dysfunction.
Symptoms of sexual dysfunction may be treated with
sildenafil (Viagra),
yohimbine (Pausinystalia
yohimbe),
amantadine (Symmetrel),
cyproheptadine, or
neostigmine (Prostigmin).
Over time, weight loss or weight gain has been associated with SSRIs. Patients may
experience weight loss initially but quickly regain weight.
Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.
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