Transdermal nitroglycerin patch for Achilles tendonitis

NEW YORK (Reuters Health) - Patches that deliver nitroglycerin through the skin do nothing to help speed healing from a common type of injury to the Achilles tendon, UK researchers have found.

Noninsertional Achilles tendinopathy is a tear in the tendon above the point where it inserts into the heel bone. The cause of the condition hasn’t been established, although overuse may be a factor in some cases, Dr. Timothy P.C. Kane, of North Hampshire Hospital in Basingstoke, and colleagues write in the American Journal of Sports Medicine.

There is little scientific evidence to support the many different approaches to treating the condition, the researchers add, although a previous study found that topical glyceryl trinitrate (GTN), in the form of the Nitroderm patch made by Schering-Plough, improved outcomes.

The authors of that study suggested that the patches -- which are normally used to treat chest pain called angina -- may have aided Achilles tendon injuries by increasing the formation of collagen and stimulating the activity of fibroblasts, the cells responsible for making connective tissue.

To investigate further, Kane and his team randomly assigned 40 patients with noninsertional Achilles tendinopathy to receive either standard physical therapy or standard physical therapy plus a daily GTN patch for six months. Patients who didn’t improve underwent surgery, at which time the researchers sampled tissue from the tendon.

There was no difference in pain or disability scores between the two groups after six months, the researchers found. And examination of tissue in those who underwent surgery found no difference in new blood vessel growth, collagen synthesis or fibroblast activity.

The findings, according to Kane’s team, suggest that the nitroglycerin patch will not help people with noninsertional Achilles tendinopathy heal any faster.

SOURCE: American Journal of Sports Medicine, June 2008.

(Reuters Health) - Patches containing nitroglycerin may help patients with common injuries to tendons, a research review suggests.

The study team focused on overuse tendon injuries in the shoulders, wrists, heels and knees that are often caused by sports or repetitive physical tasks and can lead to pain, swelling and limited mobility. Depending on its severity, the condition may be treated with physical therapy, corticosteroid injections to provide short-term pain relief or surgery to repair or replace damaged tendons.

The current study examined another treatment option, nitroglycerin patches placed on the skin, which can have fewer side effects than injections or surgery, said senior author Neal Millar of the University of Glasgow in Scotland. While topical nitroglycerin has been examined for tendon pain for more than two decades, research to date has offered a mixed picture of how well it works for this purpose, Millar said.

To get a better look at the effectiveness of this option, Millar and colleagues analyzed data combined from 10 smaller clinical trials that randomly assigned some patients with tendon pain to use nitroglycerin patches and others to an alternative treatment or to a placebo, or dummy, patch.

After six months of treatment, topical nitroglycerin provided more pain relief than a placebo, Millar’s team reports in the British Journal of Sports Medicine.

“This matters for patients because all other current pharmacological and injection therapies have failed to produce convincing results to improve patient care,” Millar said by email.

Up to one in five patients can suffer headaches from the topical treatment, and some also experienced stinging where the patches were placed, the analysis found.

Based on these results, it may make sense for patients to consider using patches in conjunction with physical therapy in initial efforts to relieve tendon pain, Millar said.

Over 12 to 24 months, however, the patches didn’t appear to affect pain when people were at rest. Longer-term use was still associated with better strength and range of motion in some instances.

One limitation of the analysis is that researchers didn’t pool data across all of the smaller studies to examine exactly how much better patches might be than a placebo. It’s also not clear if this approach would be ideal for all types of tendon injuries in all parts of the body.

Patients might also get topical nitroglycerin gels or ointments, which were not examined in the current study focused on patches.

Even so, the results suggest that patches may be a viable option for some patients, said Dr. Selene Parekh of the North Carolina Orthopedic Clinic and Duke University in Durham, North Carolina.

“The benefits are better than placebo and seem to help patients restore activities of daily living,” Parekh, who wasn’t involved in the study, said by email.

Some patients who get headaches from the patches may also be able to continue using them by cutting the dose, noted Dr. George Murrell of the University of New South Wales in Sydney, Australia.

“The treatment for this headache is to cut the patch into smaller pieces, i.e. use a smaller dose,” Murrell, who wasn’t involved in the study, said by email.

SOURCE: bit.ly/2OHzwRe British Journal of Sports Medicine, online October 9, 2018.