In Collaboration With

THERAPEUTICS

Brands

• Cymbalta
• see index for additional brand names

Generic?

• No

Class

• SNRI (dual serotonin and norepinephrine reuptake inhibitor); may be classified as an antidepressant, but it is not just an antidepressant

Commonly Prescribed For

• (bold for FDA approved)
• Major depressive disorder
• Diabetic peripheral neuropathic pain (DPNP)
• Stress urinary incontinence
• Neuropathic pain/chronic pain
• Fibromyalgia
• Generalized anxiety disorder
• Other anxiety disorders

How The Drug Works

• Boosts neurotransmitters serotonin, norepinephrine/noradrenaline, and dopamine
• Blocks serotonin reuptake pump (serotonin transporter), presumably increasing serotonergic neurotransmission
• Blocks norepinephrine reuptake pump (norepinephrine transporter), presumably increasing noradrenergic neurotransmission
• Presumably desensitizes both serotonin 1A receptors and beta adrenergic receptors
• Since dopamine is inactivated by norepinephrine reuptake in frontal cortex, which largely lacks dopamine transporters, duloxetine can increase dopamine neurotransmission in this part of the brain
• Weakly blocks dopamine reuptake pump (dopamine transporter), and may increase dopamine neurotransmission

How Long Until It Works

• Onset of therapeutic actions usually not immediate, but often delayed 2-4 weeks for depression
• If it is not working within 6-8 weeks for depression, it may require a dosage increase or it may not work at all
• Can reduce neuropathic pain within a week, but onset can take longer
• May continue to work for many years to prevent relapse of depressive symptoms or prevent worsening of painful symptoms
• Vasomotor symptoms in perimenopausal women with or without depression may improve within 1 week

If It Works

• The goal of treatment of depression and anxiety disorders is complete remission of current symptoms as well as prevention of future relapses
• The goal of treatment of diabetic peripheral neuropathic pain and fibromyalgia and chronic neuropathic pain is to reduce symptoms as much as possible, especially in combination with other treatments
• Treatment of depression most often reduces or even eliminates symptoms, but is not a cure since symptoms can recur after medicine stopped
• Treatment of diabetic peripheral neuropathic pain, fibromyalgia, and chronic neuropathic pain may reduce symptoms, but rarely eliminates them completely, and is not a cure since symptoms can recur after medicine is stopped
• Continue treatment of depression and anxiety disorders until all symptoms are gone (remission)
• Once symptoms of depression are gone, continue treating for 1 year for the first episode of depression
• For second and subsequent episodes of depression, treatment may need to be indefinite
• Use in anxiety disorders may also need to be indefinite
• Use in diabetic peripheral neuropathic pain, fibromyalgia, and chronic neuropathic pain may also need to be indefinite, but long-term treatment is not well studied in these conditions

If It Doesn’t Work

• Many patients only have a partial response where some symptoms are improved but others persist (especially insomnia, fatigue, and problems concentrating)
• Other patients may be nonresponders, sometimes called treatment-resistant or treatment-refractory
• Some depressed patients who have an initial response may relapse even though they continue treatment, sometimes called “poop-out”
• Consider increasing dose, switching to another agent or adding an appropriate augmenting agent
• Consider psychotherapy for depression or biofeedback or hypnosis for pain
• Consider evaluation for another diagnosis or for a comorbid condition (e.g., medical illness, substance abuse, etc.)
• Consider the presence of noncompliance and counsel the patient
• Some patients may experience apparent lack of consistent efficacy due to activation of latent or underlying bipolar disorder, and require antidepressant discontinuation and a switch to a mood stabilizer

Best Augmenting Combos for Partial Response or Treatment-Resistance

• Augmentation experience is limited compared to other antidepressants and treatments for neuropathic pain
• Adding other agents to duloxetine for treating depression could follow the same practice for augmenting SSRIs or other SNRIs if done by experts while monitoring carefully in difficult cases
• Although no controlled studies and little clinical experience, adding other agents for treating diabetic peripheral neuropathic pain and fibromyalgia and neuropathic pain could theoretically include gabapentin, pregabalin, and tiagabine, if done by experts while monitoring carefully in difficult cases
• Mirtazapine (“California rocket fuel” for depression; a potentially powerful dual serotonin and norepinephrine combination, but observe for activation of bipolar disorder and suicidal ideation)
• Bupropion, reboxetine, nortriptyline, desipramine, maprotiline, atomoxetine (all potentially powerful enhancers of noradrenergic action for depression, but observe for activation of bipolar disorder and suicidal ideation)
• Modafinil, especially for fatigue, sleepiness, and lack of concentration
• Mood stabilizers or atypical antipsychotics for bipolar depression, psychotic depression or treatment-resistant depression
• Benzodiazepines
• If all else fails for anxiety disorders, consider gabapentin, pregabalin, or tiagabine
• Hypnotics or trazodone for insomnia
• Classically, lithium, buspirone, or thyroid hormone for depression

Tests

• Check blood pressure before initiating treatment and regularly during treatment