Is androgen alopecia a known adverse drug reaction (ADR) to citalopram treatment?/nThe question con

Fråga: Is androgen alopecia a known adverse drug reaction (ADR) to citalopram treatment?

The question concerns a 32-year-old woman who for the last two years has been treated with citalopram for depression. She has had diffuse thinning of the hair over the scalp during the last 6 months. She has no other drugs.

Sammanfattning: Establishing causality between a drug and alopecia is difficult as alopecia might occur spontaneously and may also be caused by a number of conditions like severe illness or stress. If SSRI-induced alopecia does exists, it appears to be a rare adverse reaction to SSRI- treatment. If a patient develops alopecia during SSRI treatment and other causes have been excluded, changing the treatment to another antidepressant could be considered.

Svar: Hair growth is divided into two phases. The anagen phase is the growth phase of the follicle, while the telogen phase is the resting phase. Drug-induced hair loss (alopecia) is usually divided into two different patterns. In anagen defluvium (shedding of hair) the drugs induce an abrupt cessation of the growth phase of the hair, and the hairs are shed within days or weeks. It can be caused by chemotherapeutic agents ie methotrexate. In telogen defluvium, the follicle is precipitated into resting phase, and the hairs are shed after 2-4 months (1). This may occur spontaneously, and may be precipitated by other factors like stress, hormonal contraceptives, iron deficiency or hypothyroidism. The prognosis is generally good (2).

Drugs that are known to induce alopecia are ie anticoagulants, lithium, beta-blockers and interferon. However, most cases of telogen defluvium are secondary to severe illness, and causality with a drug is therefore difficult to establish (1).

Androgenic alopecia is telogenic defluvium of genetic predetermination. Both men and women are affected, often starting in the third decade. It presents as bitemporal recession of the hairline as well as loss over the scalp in men. In women a diffuse thinning over the top of the scalp can be seen. Laboratory tests with measurements of serum levels of testosterone, dihydroepiandrosterone (DHEA), iron, thyroid function tests and blood count will identify most other causes of hair thinning in premenopausal women (2). Not surprisingly, drug-induced androgenic alopecia can be seen with drugs that exhibit androgenic activity such as stanozolol and oestrogen antagonists (1).

A question of citalopram and alopecia has previously been answered in Drugline. At that time, there were two reports of hair loss in connection with citalopram treatment. In a published case, the hair loss occurred within the first month of starting treatment, with big pieces of hair falling of (anagen type). In the other case, there was concomitant treatment with riperidone, which has also been reported to cause hair loss (3).

In the literature, alopecia is mentioned as a known adverse effect of sertraline (4).

In a recently published study, the association between alopecia and SSRI treatment was evaluated using data from the Swedish Adverse Drug Reaction database (SWEDIS) and the WHO Adverse Drug Reaction database (Vigibase). Twenty seven cases of alopecia in connection with SSRI treatment reported to SWEDIS were included in the analysis. The total number of alopecia reports for SSRIs in Vigibase were 1079.

Firstly, using data from SWEDIS, the reporting incidence in relation to sales statistics were calculated as the number of reported cases of alopecia per million patient-years in Sweden. There was a significantly higher reporting incidence for sertraline (20.1 (10.7; 34.4)) than for citalopram (4.5 (1.8; 9.3)) (5).

The Bayes confidence propagation neural network (BCPNN) method was then used to further estimate the association between SSRIs and alopecia. For sertraline, a statistically significant association could be seen in both Vigibase (1.29 (1.14; 1.44 95 % CI)) and SWEDIS (1.63 (0.85; 2.41)). Citalopram was also significantly associated with alopecia in Vigibase (1.22 (0.97; 1.47)). No significant associations were found for the other SSRIs (5).

The authors suggest a possible mechanism by which SSRI might cause alopecia. Human skin can produce serotonin and transform it into melatonin. Melatonin has in its turn been implicated in the hair growth cycle. It is possible that SSRI treatment may affect the serotonin homeostasis in the skin and thereby affecting the balance between hair growth and hair shedding (5).

However, caution should be used when interpreting the results of the study. The study size is small, and the causality between the reported ADR and the offending drug has not been evaluated in many cases. In general, there are several factors influencing ADR reporting that may create bias (5).

In the present case, other causes of alopecia should be ruled out. If the suspicion that citalopram caused the patients symtoms persists, changing the treatment to another antidepressant could be considered.

We recommend that this case is reported to the regional adverse drug reaction monitoring centre.