At doses lower than those needed to treat depression, antidepressants can relieve chronic pain in conditions ranging from diabetic neuropathy, migraine and tension headaches, to osteoarthritis and fibromyalgia.
Experts explain, however, that most medications have significant associated side-effects and the ability to tolerate these side effects varies between individuals.
Side effects may depend on other medications an individual is using, or could be influenced by other existing health issues. Therefore, predicting the ability to tolerate such side effects could be crucial for the success of an antidepressant in treating pain.
This scenario is discussed in a recent article by Dr. Carina Riediger and colleagues in Dr. Timo Siepmann’s group at the University Hospital Carl Gustav Carus, in Dresden, Germany. The paper appears in the online journal Frontiers in Neuroscience.
“Understanding adverse effects and their impact on patients’ quality of life is crucial in modern clinical medicine and poses a substantial challenge to clinicians who face a exponentially growing range of available medical therapies” said Siepmann, the principal investigator of this study.
To help physicians match a chronic pain sufferer to a suitable antidepressant, their group performed a systematic study and meta analysis of the reported adverse effects for a wide variety of commonly used antidepressant drugs, each with its own side effect profile.
These antidepressants fall into different categories based on their mechanism of action, such as tricyclic antidepressants amitriptyline (Elavil) and nortriptyline (Pamelor), and serotonin reuptake inhibitors venlafaxine (Effexor), duloxetine (Cymbalta) and milnacipram (Ixel), among others.
The study collected all reported adverse effects for these drugs in the clinical literature from the past two decades. These side effects ranged from dizziness, dry mouth, and drowsiness, to palpitations, weight gain, sexual and urinary dysfunction, and hypertension, to name a few. The researchers also took into account whether treatment was discontinued due to the severity of these side effects.
Researachers found that almost all antidepressants presented significant side effects, and no drug was clearly superior to others. However, clinical data also showed that some individuals might better tolerate certain side effects than others, and therefore, the authors recommend personalized medicine.
For instance, dizziness and drowsiness as side effects may not be acceptable for individuals who drive vehicles or operate heavy machinery. On the other hand, some sedation might be tolerated, and perhaps even be desirable, in a chronic pain patient with sleep disruptions or insomnia.
These results may help physicians improve treatment outcomes by better matching the health status of chronic pain patients to their antidepressant medication.
“Dr. Riediger’s work contributes to this understanding, but further research is needed to improve general treatment recommendations and enable personalized multimodal therapy which is tailored to the patient’s individual health situation and includes non-pharmacological strategies in addition to pharmacotherapy,” Siepmann said.