New phase III trials of a drug designed to ease spasticity caused by multiple sclerosis (MS) have been launched.

Drug maker GW Pharmaceuticals said that Sativex was undergoing the trials following feedback from European regulators, with the new trial focusing on how the drug affects people who respond to it.

The firm said that the first phase of the trial would identify "responders", with around 244 people who fall into this category moving on to be studied in the second part, which will examine the results of patients treated with Sativex compared to those who take a placebo for six weeks.

MS can cause serious muscle stiffness and spasms as nerves become hardened and incapable of successfully carrying the signals that govern movement.

This can have a significant effect on sufferer's lives, making it difficult to carry out day to day activities, such as walking.

Masters is a global healthcare solution provider which can supply medical professionals with medicines still undergoing clinical trials to help meet the needs of patients who cannot take existing drugs or have another special requirement.