Clinical Drug Experience Knowledgebase

A Randomized Double Blind Placebo Controlled Cross-over Trial of Baclofen and Diazepam Suppositories for the Management of Pelvic Floor Myalgia

Chronic pelvic pain is a complex multi-faceted problem that places a substantial burden on the healthcare resources. In Canada, the average hospital related cost for women requiring surgery or inpatient admission for chronic pelvic pain is $25 million each year. Chronic pelvic pain is defined as either persistent pain for at least 6 months or "recurrent episodes of abdominal/pelvic pain, hypersensitivity, or discomfort, often associated with elimination changes and sexual dysfunction in the absence of an organic etiology." Chronic pelvic pain is common and affects women of all ages and backgrounds. 15-20% of women have chronic pelvic pain lasting for more than 1 year.

Pelvic floor myalgia is an important and common contributor to chronic pelvic pain that may be present alone or may co-exist with other gynecological, urological, colorectal, and musculoskeletal medical conditions. The International Urogynecological Association/International Continence Society joint report published in February 2017 defines pelvic floor myalgia as pain in the musculature of the pelvic floor.6 Patients with high-tone pelvic floor dysfunction (HTPFD) have levator hypercontractility and present with pain with internal vaginal examination and intercourse. In a 2011 prospective cross-sectional study by Fitzgerald et al., 63% of patients with self-reported chronic pelvic pain examined by a physician and 73.7% of patients examined by a physiotherapist were found to have pelvic floor myalgia. Although pelvic floor myalgia is a common condition encountered in gynecology, it is frequently an unrecognized and under-treated component of chronic pelvic pain. Pelvic floor myalgia has a significant impact on the patient's quality of life. Persistent chronic pain may result in patient's anxiety, low mood, depression, sleep disturbances, feeling of hopelessness and helplessness, frustration, and psychological distress.

The first line of treatment for pelvic floor myalgia is pelvic floor muscle relaxation. Reducing the resting tone of pelvic floor musculature has been shown to improve chronic pelvic pain. Current treatment options for pelvic floor myalgia include pelvic floor physiotherapy, Thiele massage, biofeedback with electrical stimulation, behavioural modifications, acupuncture, medications such as antidepressants,1 trigger point injections with botulin A toxin, warm sitz baths, and neuromodulation.

Recently, intravaginal diazepam has been used an off-label treatment option for high-tone pelvic floor myalgia. Diazepam is a benzodiazepine derivative that has both antispasmotic and anxiolytic activity. It is used as a muscle relaxant and enhances the inhibitory action of gamma-amino butyric acid (GABA) on neuronal excitability, resulting in decreased action potentials. The benefit of local therapy is the avoidance of the common side effects of benzodiazepines such as drowsiness, fatigue, and ataxia. Currently, evidence is lacking in regards to the effectiveness of intravaginal diazepam on treatment of chronic pelvic pain. The 2010 retrospective chart review of 26 patients by Rogalski et al. revealed clinically significant reduction in Visual Analogue Scale for Pain (VAS-P) and Female Sexual Function Index (FSFI) with diazepam suppositories used for 30 days as an adjuvant therapy to pelvic floor physiotherapy and intramuscular trigger point injections. Similarly, the 2011 study revealed 62% improvement in symptoms with intravaginal diazepam.

Baclofen is a skeletal muscle relaxant. It is a GABA-B receptor agonist which is commonly used for treating spasticity. The literature on topical baclofen use in pelvic floor dysfunction is minimal. Topical therapy is advantageous to avoid the common systemic side effects such as drowsiness, hypotonia, hypotension, and headache. A retrospective study examining the use of topical baclofen for provoked vulvodynia showed an improvement in pain and sexual function.

Baclofen may also be used in combination with diazepam for treatment of pelvic floor myalgia. A 2016 retrospective chart review performed at the University of Saskatchewan revealed a reduction in both dyspareunia and pelvic floor muscle spasm with the use of baclofen and diazepam vaginal suppositories.