A three-part study to investigate the incidence and potential etiologies of tadalafil-associated back pain or myalgia

Abstract

The potential mechanisms underlying back pain and/or myalgia experienced by men taking tadalafil were investigated. An integrated analysis of 10 placebo-controlled tadalafil clinical trials (N=1846) showed that the incidence of back pain and/or myalgia was 9.4% in patients receiving tadalafil 10 mg (N=394), 8.3% in patients receiving tadalafil 20 mg (N=883) and 3.7% in placebo-treated patients (N=569). One (0.3%) patient receiving tadalafil 10 mg, six (0.7%) patients receiving tadalafil 20 mg, and no patients receiving placebo discontinued treatment due to back pain and/or myalgia. In a prospective study in healthy volunteers, no substantial changes were observed in laboratory markers indicative of inflammation or muscle damage, and tadalafil did not affect renal plasma flow nor produce lumbar or gluteal myositis by positron emission tomography scan or magnetic resonance imaging. Although the mechanism of back pain and/or myalgia remains unknown, these events appear to be self-limiting and a general effect of phosphodiesterase 5 inhibition.

Tadalafil in the treatment of erectile dysfunction; an overview of the clinical evidence

“…The underlying symptoms include diffuse bilateral lower lumbar gluteal, thigh, or thoracolumbar muscular discomfort, exacerbated by recumbency. The integrated analysis of ten placebo-controlled tadalafil studies, including 1846 patients (Seftel et al 2005), showed that laboratory markers of inflammation or muscle damage and renal plasma flow were unchanged with respect to baseline, and no lumbar or gluteal myositis was evidenced by positron emission tomography scan or magnetic resonance imaging.…”

“…When taken on demand, tadalafil 20 mg versus placebo allows a range of 62%–74% (vs 0%–33%) of successful intercourse attempt rate up to 36 h (p<0.001 up to 24 h; p=0.017 up to 36 h) (Allen et al 2004; Seftel et al 2005). …”

Prevention of Tadalafil Induced Backache in Erectile Dysfunction Patients

“…[3] Other research by Carson et al and Montorsi et al put discontinuation rate due to total adverse events as 3.2% and 6.4% respectively. [3,4] The relative high affinity of tadalafil for phosphodiesterase 11, an isoform found in skeletal muscle is considered to be related to the higher incidence of back pain or myalgia in patients on tadalafil according to research by Samuel Washington et al [5] Though research say this back pain is self-limiting, Adseftel et al [1,8] Psychiatrists, sexologists and urologists must definitely pay attention to the emotional distress associated with back pain, particularly when it develops in a patient already suffering from erectile dysfunction. This is much more important in an Indian scenario filled with myths and misconceptions about sex, which further complicates the problem.…”

“…[2,5] In spite of repeated reassurances and explanation that this pain is selflimiting (Adseftel et al), their fear is difficult to alleviate. [1] So they were allowed to discontinue the drug with an explanation that symptoms are due to increased blood supply (Adseftel et al) and it will stop once the drug is discontinued. [6,7,8] They were then individually explained the benefits of tadalafil versus side effects and reassured that restarting tadalafil along with the two add-on drugs Aceclofenac 100 mg + Chlorzoxazone 250 mg + Paracetamol 325 mg combination and 2.…”

“…(24 to 48 hrs.). [1] But in a day-to-day practice, some patients could not tolerate this back pain or myalgia and discontinued tadalafil. [2,3,4] In these patients successful reintroduction of tadalafil without this distressing back pain or myalgia with the help of two add-on drugs (Combination) was attempted in this study.…”