The effectiveness of pregabalin with or without agomelatine in the treatment of chronic low back pain: a double-blind, placebo-controlled, randomized clinical trial

Background

Although various pharmacological and nonpharmacological treatments are available for the chronic low back pain (CLBP), there is no consensus on the best optimal treatment for this condition. This study aimed to investigate the efficacy of co-administration of pregabalin and agomelatine versus pregabalin with placebo to treat CLBP.

Methods

Forty-six CLBP patients without the surgical indication referred to the outpatient orthopedic clinic of Rasoul-e-Akram Hospital, Tehran, Iran, were randomly divided into two study groups: Group A [pregabalin (75 mg twice per day) + placebo] and Group B [pregabalin (75 mg twice per day) + agomelatine (25 mg per night)]. Patients were evaluated at weeks 0, 4, and 8. Outcome measures were the Persian versions of the Brief Pain Inventory (BPI) interference scale, Roland-Morris Disability Questionnaire (RMDQ), The Hospital Anxiety and Depression Scale (HADS), 36-Item Short Form Survey (SF-36), and General Health Questionnaire-28 (GHQ-28) were used.

Results

At weeks 4 and 8 after the intervention, all evaluated measures showed significant improvement in both study groups (P < 0.01). The mean improvement of GHQ-28 was 3.7 ± 1.22 in group A and 13.1 ± 4.71 in group B. This difference was statistically significant (P = 0.003). Other outcomes did not vary substantially between the two research groups. Agomelatine treatment was well tolerated, with no significant adverse effects seen in patients. Liver tests of all patients were routine during the study period. Major adverse effect was not seen in any patient. The prevalence of Minor side effects was not significantly different between two study groups.

Conclusion

Compared with the pregabalin and placebo, co-administration of pregabalin and agomelatine had no added effect on improving pain scores in CLBP patients. However, the patients’ general health was significantly improved after the combined administration of pregabalin and agomelatine.

Trial registration

The study protocol was registered in the Iranian Registry of Clinical Trials before starting the study (NO.IRCT20200620047852N1, Registration date: 23/06/2020).

Opioid system mediated anti-nociceptive effect of agomelatine in mice

AIMS

This study was planned to examine the antinociceptive efficacy of agomelatine against acute mechanical, thermal, and chemical nociceptive stimuli, as well as to determine the opioid receptor subtypes mediating these effects.

MAIN METHODS

Tail-clip, hot-plate, and acetic acid-induced writhing tests were performed to evaluate anti-nociceptive effect. Besides, possible effect of agomelatine on the motor coordination of animals was assessed with a Rota-rod test.

KEY FINDINGS

Agomelatine (40mg/kg and 60mg/kg) significantly prolonged the reaction time of mice in both the tail-clip and hot-plate tests, suggesting the antinociceptive activity is related to both spinal and supraspinal mechanisms. This drug also reduced the number of writhing behaviors indicating the presence of a peripherally mediated antinociceptive effect. Rota-rod testing displayed no notable effect on the motor activity of the animal supporting the conclusion that the observed antinociceptive effect is specific. The agomelatine-induced antinociceptive activity abrogated following pretreatment with naloxone (a non-selective opioid receptor antagonist, 5.48mg/kg, i.p.), which suggested the participation of opioid mechanisms to the antinociception. The possible contribution of μ, δ and ҡ subtypes of opioid receptors to the anti-nociceptive effect were evaluated using naloxonazine (7mg/kg, s.c.), naltrindole (0.99mg/kg, i.p.), and nor-binaltorphimine (1.03mg/kg, i.p.), respectively. Pretreatments using these antagonists abolished the antinociceptive activity of agomelatine in all of the nociceptive test paradigms used, which pointed out that μ, δ, and ҡ opioid receptors participated to the action of agomelatine on pain.

SIGNIFICANCE

These results demonstrated the therapeutic potential of agomelatine in the treatment of pain disorders.

Diffuse Hair Loss Induced by Sertraline Use

Hair loss is a rare side effect of psychotropic drugs. The most related drug class with this side effect is the mood stabilizers. Studies reporting the sertraline-induced alopecia are limited in number. Sertraline is a potent antidepressant which inhibits the serotonin reuptake from the presynaptic terminals selectively. The reason for hair loss could not be elucidated completely. Psychotropic drugs are usually considered to lead to hair loss through influencing the telogen phase of hair follicle. This paper reports a 21-year-old male with diffuse hair loss induced by sertraline use and improved by quitting the drug. To the best of our knowledge, there are no other case reports on sertraline-induced alopecia within 2 weeks.