(See Table IX - Adjuvant Analgesics, pages -----.)
Antidepressants - Antidepressants are used for pain relief even when a
patient is not clinically depressed. These drugs have intrinsic analgesic
properties and are most useful for relief of neuropathetic pain. First
generation tricyclics such as amitriptyline hydrochloride (Elavil) and
doxepin hydrochloride (Sinequan) have been especially helpful. Start with
10-25 mg at bedtime and increase the dose until symptomatic pain relief
occurs. Lower doses should be used in patients over 40 years. The usual
effective dose range is 50-150 mg, but occasionally up to 300 mg is
needed. Antidepressants are usually given as single doses at bedtime, but
occasionally 10-30 mg of the total dose may also be given once or several
times during the day. If depression and sleep disturbance are present,
they frequently will improve too.
Experience is limited with the newer, more action specific antidepressants,
such as the serotonin specific reuptake inhibitors (SSRIs) for the
treatment of neuropathic pain. If neuropathic pain treatment fails with
the tricyclic antidepressants there is no reason not to give these newer
agents a therapeutic trial.
Anticonvulsants - Anticonvulsants are helpful for neuropathic pain because
they suppress neuronal firing. Carbamazepine (Tegretol) is very effective
but must be started at a low dosage of 100 mg at bedtime and then
gradually increased to 100-400 mg three times per day (T.I.D.) depending
on clinical response and blood levels. Phenytoin sodium (Dilantin), 100 mg
two times per day (B.I.D.) to four times per day (Q.I.D.), or divalproex
sodium (Depakote), 250-500 mg B.I.D. to Q.I.D. depending on symptom relief
or blood levels, may be used instead of carbamazepine. Clonazepam
(Klonopin), starting with half of a 0.5 mg tablet at bedtime and
increasing to 1-2 mg and occasionally up to 5-l0 mg per day, is also
frequently effective. Gabapentin (Neurontin) is a newer anticonvulsant
that has also shown promise in the treatment of neuropathic pain.
Miscellaneous drugs - Hydroxyzine hydrochloride, 25-100 mg intravenously
Q.I.D., frequently relieves nausea and anxiety in addition to pain. It is
considerably less effective when given by mouth. Haloperidol (Haldol),
2-10 mg orally (p.o.) or I.V. per day in divided doses or all at bedtime,
may also be an effective treatment for pain, especially when nausea,
anxiety, or sleep disturbance coexist.
Corticosteroids are extremely useful in the treatment of bone pain and
any pain caused by swelling around pain sensitive structures.
Dexamethazoneis the one most commonly used because of its sparing effects
on electrolytes. A loading dose of 100 mg may be used followed by 4 mg
Q.I.D. The usual precautions with using corticosteroids should be
followed.
