Duloxetine in Patients With Diabetic in Peripheral Neuropathic Pain With or Without Co-morbid Major Depressive Disorder

A 12 Weeks Open Label Two Parallel Groups Study to Assess the Efficacy of Orally Administered Duloxetine 60 mg and 120 mg Per Day on Treatment Outcomes in Patients With Diabetic Peripheral Neuropathic Pain With and Without Co-morbid Major Depressive Disorder. The Primary Objective of This Study is to Evaluate Whether the Efficacy of Duloxetine Given as 60 mg to 120 mg Once Daily (QD), Measured by the BPI Interference Score After 12 Weeks Shows a Clinically Relevant Improvement in the DPNP Patients With Co-morbid MDD

The primary objective is to evaluate, separately in diabetic polyneuropathic pain (DPNP) patients with and without co-morbid major depressive disorder (MDD), whether duloxetine given as 60 mg to 120 mg once daily (QD) leads to a clinically relevant improvement as measured by the change in Brief Pain Inventory (BPI) 24 hours average interference score from baseline to after 12 weeks. A clinically relevant improvement will be demonstrated if the confidence interval for the mean change from baseline does not lie above the clinically relevant change of -1.35. If statistically significant results are obtained for the DPNP patients with MDD, then the same evaluation will be performed for the DPNP patients without MDD in another confirmatory analysis.

As secondary objectives the study will compare the two groups (MDD+/MDD-) regarding efficacy of duloxetine on BPI severity scales, the distribution of different percentages of pain reduction among the patient population, and the patients and physicians impressions of severity and improvement of pain.

The study will also compare treatment outcomes regarding patient-relevant functionality and quality of life (QoL) between the two groups (MDD+/MDD-) by evaluating each single BPI interference item, the Short Form 12 (SF-12) Health Questionnaire and the West Haven Multidimensional Pain Inventory (MPI).

As a third group of secondary objectives the efficacy of duloxetine of the psychological symptoms (e.g. depression) of DPNP patients with or without depression will be assessed using the Hamilton depression scale, the Beck Depression Inventory-II and the hospital Anxiety and Depression Scale.

Further the effect of duloxetine treatment on fasting blood glucose (FBG) and hemoglobin A1c (HbA1c) will be evaluated.

To monitor safety and tolerability, treatment discontinuation rates, treatment emergent adverse events, change in vital signs, laboratory results and suicidal thoughts will be assessed.

Inclusion criteria:

1. Present with pain due to bilateral peripheral neuropathy (according to International Statistical Classification of Diseases and Related Health Problems 10 (ICD 10).
2. To qualify for the MDD+ cohort, patients need to meet the ICD-10 criteria for MDD. Furthermore, Hamilton rating scale for depression 17 (HAMD-17) scores need to match with the ICD-10 criteria for qualification of the MDD+ or MDD- groups.
3. Male or female outpatients at least 18 years of age.
4. Females with child bearing potential must test negative for a serum pregnancy test at Visit 1. Females of child-bearing potential (not surgically sterilized and between menarche and 1 year post-menopause) must agree to utilize medically acceptable and reliable means of birth control as determined by the investigator during the study and for 1 month following the last dose of the study. Examples of reliable methods include use of oral contraceptives or Depo-Clinovir Contraceptive Injection (sterile medroxyprogesterone acetate suspension, Pharmacia), partner with vasectomy, diaphragms with contraceptive jelly, cervical caps with contraceptive jelly, condoms with contraceptive foam, or intrauterine devices. Women who are pregnant or breast-feeding may not participate in the study.
5. Educational level and degree of understanding such that they can communicate intelligibly with the investigator and study coordinator.
6. Judged to be reliable and agrees to keep all appointments for clinic visits, tests, and procedures required by the protocol.

Exclusion criteria:

1. Have already a diagnosis of Depression and are currently treated with an antidepressant medication for depression, when entering the study.
2. Suffer from pain that cannot be clearly differentiated from or conditions that interfere with the assessment of DPNPain.
3. Had a historical exposure to drugs known to cause neuropathy, that could have been responsible for neuropathy.
4. Have previously been treated with duloxetine (for DPNP or MDD)
5. Are judged to be at suicidal risk by the clinical investigator or as defined by a score of 2 or greater on question 9 of the Beck Depression Inventory-II (BDI-II).
6. Had a history of substance abuse or dependence within the past year, excluding nicotine and caffeine.