Drugs in this class are used for:

Depression

 Drugs in this class include amitriptyline, clomipramine, dosulepin (dothiepin), doxepin, mianserin, trazodone, and trimipramine. Also in this class, but with less sedative properties include imipramine, lofepramine, and nortriptyline. TCAs are often used to treat moderate to severe depression, particularly where sedation is desirable, but some are effective in the management of panic disorders, neuralgia and nocturnal enuresis in children. For more information, refer to individual drug SPCs.

 

Dosage regimen

 

* Tricyclic antidepressants (TCAs), such as amitriptyline, are taken in divided doses during the day or as a single dose at bedtime. Most TCAs have long half-lives so modified release preparations are not usually necessary.

 

Patient's knowledge of the medicine's use

 

* TCAs can taken up to two weeks to work. An improvement in sleep is usually the first benefit felt by the patient.

 

Is the medicine working?

 

* Has the patient been taking the correct number of tablets a day for at least four weeks, but without feeling any benefit? If so, refer to the prescriber as the medication strength may need to be increased, or a different agent tried (either in the same or a different class).

 

Side effects

 

* TCAs commonly cause antimuscarinic side effects such as dry mouth, sedation, blurred vision and constipation.

 

* If antidepressants are initiated slowly and carefully, tolerance of side effects may develop, but this needs balancing against the need to obtain a rapid therapeutic effect.

 

* Other common side effects of TCAs are drowsiness and hypotension. The elderly are particularly susceptible.

 

* Imipramine has more marked antimuscarinic and cardia side effects than doxepin, mianserin and trazodone.

 

* Amitriptyline and dosulepin are particularly dangerous in overdose, because of cardiac side effects, so should not be used indepression.

 

* Lofepramine has a lower incidence of antimuscarinic and sedative side effects and is less dangerous in overdose, but has been linked to hepatic toxicity.

 

* Mianserin is particulary associated with the incidence of hepatic and haemotological side effects.

 

* TCAs are sometimes associted with convulsions, so should be prescribed with caution for those with epilepsy.

 

Monitoring

 

* All patients started on antidepressants should be reviewed every one to two weeks initially.

 

* All antidepressants, including TCAs, can cause hyponatraemia. The elderly are particularly susceptible, so any such patients reporting drowsiness, confusion or convulsions should be urgently referred.

 

* Patients who have been taking antidepressants for a long time may want to stop. However, this should only be done under the supervision of the prescriber and only after remission of symptoms has been achieved for a minimum of four months. The antidepressant dose must be reduced slowly, over a period of at least four weeks, to avoid the emergence of withdrawal symptoms.

 

* Patients with a history of recurrent depression should be advised that they will need maintenance treatment for at least five years, and possibly even indefinitely.

 

Lifestyle

 

* Exercise can help reduce depression, so encourage the patient to join the gym or try yoga.

 

* The patient could try computerized cognitive behaviour therapy (CBT). This therapy helps a person to alter negative thoughts into positive ones. The GP will be able to advise on local availability.

 

 

Uzma Chaudhry, relief pharmacist, Lloydspharmacy, Oxfordshire

 

 

 

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