Researchers at Pfizer Inc. recently reported that patients with disorders related to pain such as fibromyalgia respond positively to treatment with the company’s drug Lyrica within 3 to 4 weeks. The study was published in the journal Dovepress and is entitled “Temporal analysis of pain responders and common adverse events: when do these first appear following treatment with pregabalin”.

Pregabalin, marketed by Pfizer under the trade name Lyrica, is a drug indicated for the treatment of anxiety disorders and several conditions related to neuropathic pain including fibromyalgia, spinal cord injury, diabetic peripheral neuropathy (DPN; refers to nerve damage caused by diabetes) and postherpetic neuralgia (PHN; refers to nerve damage caused by herpes zoster infection).

Fibromyalgia is a disorder characterized by widespread chronic musculoskeletal pain, incapacitating fatigue, stiffness and numbness in certain parts of the body, painful response to pressure, headaches, poor sleep quality, anxiety or depression and mood alterations.

Fibromyalgia, spinal cord injury, DPN and PHN are all linked to chronic pain and can affect people’s ability to conduct simple daily tasks, compromising their health-related quality of life. A better understanding of the impact of pregabalin treatment in patients with these chronic pain conditions is necessary.

In the study, researchers analyzed data from five randomized, placebo-controlled clinical trials assessing flexible-doses of Lyrica (150 to 600 mg/day) for the treatment of those chronic pain conditions. The trials were conducted for a period of 8 to 16 weeks and the pregabalin dose was tailored according to each patient’s needs. The data were organized into three groups depending on the disease assessed: 498 patients with fibromyalgia, 356 with spinal cord injury and 514 with either DPN or PHN. Patients were classified as responders if they presented a mean pain score reduction from baseline equal or greater than 30% or 50%. At each week, patients were checked for the emergence of adverse events.

Overall, the researchers found that the majority of responders to Lyrica emerged during the first 3 to 4 weeks into treatment. Most common adverse events were also reported within the same period.

In the particular case of fibromyalgia, researchers found that by the second week of treatment, 19.9% of the patients under Lyrica treatment improved by 30% versus only 7.7% for patients in the control group. At week 6, 24% of the fibromyalgia patients who received Lyrica were 50% responders in comparison to 10.5% of patients in the placebo group. The most common adverse events reported were dizziness, somnolence, increased weight and constipation.

The research team concluded that in general, patients under therapeutic doses of pregabalin who are therapy responders are likely to respond to treatment within the first 4 weeks. Adverse events are also expected to emerge within 3 to 4 weeks of treatment with Lyrica.

The team believes their findings are important to guide clinical management of diseases susceptible to Lyrica treatment, and for the design of new proof-of-concept studies, supporting 3 to 4 weeks trials to assess pregabalin in chronic pain conditions.