A pooled analysis of three studies showed that Duloxetine ( Cymbalta ) significantly improves physical, social and emotional functioning, in addition to overall health, in patients with pain associated with diabetic peripheral neuropathy ( DPNP ), compared with those treated with placebo.

In the pooled analysis of more than 1,000 DPNP patients, those treated with 60 or 120 mg of Cymbalta ( given as 60 mg either once or twice daily ), reported significant improvements in all functional components defined in three commonly used scales -- the interference portion of the Brief Pain Inventory ( BPI ), the Short Form 36 ( SF-36 ) and the European Quality of Life Instrument 5D version ( EQ-5D ).

The patients, treated with Cymbalta, reported significantly less interference from pain on key measures of physical functioning, including their ability to walk, work and sleep. On a social level, patients taking Cymbalta reported significantly less interference from pain on their relationships with other people and their enjoyment of life. Additionally, Cymbalta patients reported significantly less interference from pain on mental health and mood.

Nearly 5 million Americans experience the persistent tingling, burning or stabbing pain caused by uncontrolled diabetes, which can have a tremendous impact on a patient's quality of life.
Painful diabetic neuropathy can cause patients to feel isolated and worthless, as the condition limits the ability to participate in life.
Many DPNP patients have trouble enjoying family activities, and may even need to change jobs as a result of the pain.

The FDA ( Food and Drug Administration ) approved Cymbalta in September 2004 as the first prescription drug proven to reduce DPNP in adults.
Cymbalta is also approved to treat major depressive disorder in adults.

Compared with patients in the study who received placebo, those treated with 60 or 120 mg of Cymbalta per day reported significant improvements in

- functioning, according to the average of the seven questions on the interference portion of the BPI.

- bodily pain, general health, mental health, physical function, role in physical activity, emotional role, social function and vitality, according to the SF-36.

- general health ( mean change of 0.10, compared with 0.15 and 0.16 ), according to the EQ-5D.

- pain, including 24-Hour Average Pain Severity, 24-Hour Worst Pain Score, Night Pain Score, McGill Pain Total Score, CGI-Severity, PGI Improvement and BPI Severity.

The data were pooled from three 12-week multicenter, double-blind studies.
In one study ( n=457 ) patients diagnosed with DPNP were randomly assigned to receive 20 mg of Cymbalta once daily, 60 mg of Cymbalta once daily, 60 mg of Cymbalta twice daily or placebo.
In the other two studies ( n=334, n=348 ) patients diagnosed with DPNP were randomly assigned to receive 60 mg of Cymbalta once daily, 60 mg of Cymbalta twice daily or placebo.

Functional outcomes were measured based on patients' answers on the interference portion of the Brief Pain Inventory, the Short Form 36 and the European Quality of Life Instrument 5D version.
The Interference Portion of the BPI is commonly used in pain trials to measure the degree to which pain interferes with daily life ( i.e. general activity, walking, working, sleep, mood, relationships and enjoyment of life ).

The SF-36 consists of 36 items that evaluate eight health domains related to quality of life: bodily pain, general health, mental health, physical function, role-physical, role- emotional, social function and vitality.
The European Quality of Life Instrument 5D measures mobility, usual activities, self care, pain and discomfort, and anxiety and depression.

Only those who completed one of the three studies were included in the analyses. Patients treated with Cymbalta 20 mg once daily were excluded from the analyses.

Researchers believe Cymbalta reduces diabetic peripheral neuropathic pain by blocking the re-absorption of serotonin and norepinephrine, neurotransmitters involved in regulating a person's sensitivity to pain.
These chemical messengers are part of the body's own internal pain-relief system and, in the spinal cord, exert an analgesic effect in descending pain pathways.
Cymbalta is also indicated to treat major depressive disorder in adults.

According to the National Institute of Diabetes & Digestive & Kidney Diseases, approximately half of those with diabetes have some form of nerve damage, or neuropathy, but not all will develop symptoms.
While nerve problems can occur at any time, the highest rates are among those who have had diabetes for at least 25 years.
People who have had problems controlling their blood sugar levels, have high blood pressure, are overweight, have high levels of blood fat, or are over the age of 40, may also have a greater risk of developing diabetic peripheral neuropathy.
Symptoms can include numbness, tingling or pain and weakness in the toes, feet, legs, hands, arms and fingers. These symptoms are often worse at night.

In clinical studies of Duloxetine for the management of neuropathic pain associated with diabetic peripheral neuropathy, the most common side effects were nausea, sleepiness, dizziness, constipation, dry mouth, increased sweating, decreased appetite, and loss of strength or energy.
In clinical studies of Duloxetine for depression, the most common side effects were nausea, dry mouth, constipation, decreased appetite, fatigue, sleepiness, and increased sweating.

Source: American Diabetes Association ( ADA ) 65th Annual Scientific Sessions, 2005


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