Duloxetine hydrochloride is a potent and balanced dual reuptake inhibitor of serotonin (5-HT) and norepinephrine (NE). It is a bicyclic thiophene derivative and is classified as a Serotonin-Norepinephrine Reuptake Inhibitor (SNRI). In the Indian context, it is widely prescribed for Major Depressive Disorder (MDD), Generalized Anxiety Disorder (GAD), Diabetic Peripheral Neuropathic Pain (DPNP), and Chronic Musculoskeletal Pain. The 20mg strength is often used for initiation of therapy, dose titration, or as a maintenance dose in patients sensitive to higher doses.
Adult: MDD & GAD: Initiate at 20-40 mg once daily, may increase to 60 mg once daily based on response. 20mg is a common starting and maintenance dose. DPNP & Chronic Pain: Initiate at 20-30 mg once daily, may increase to 60 mg once daily. Maximum recommended dose is 60 mg/day. For higher doses, clinical monitoring is essential.
Note: Swallow capsule whole with water. Do not crush, chew, or open the capsule and mix contents with food/liquid, as this destroys the enteric coating and may increase side effects. Can be taken with or without food, but taking with food may improve tolerability. Administered once daily, preferably at the same time each day.
Duloxetine is a potent and relatively balanced inhibitor of neuronal serotonin (5-HT) and norepinephrine (NE) reuptake with minimal affinity for other neurotransmitter receptors (e.g., muscarinic, histaminergic, alpha-1 adrenergic). By increasing the synaptic concentrations of 5-HT and NE in the central nervous system (CNS), it enhances serotonergic and noradrenergic neurotransmission. This dual action is believed to underlie its efficacy in depression, anxiety, and pain modulation via descending inhibitory pain pathways in the brain and spinal cord.
Pregnancy: Pregnancy Category C (US FDA). Data in humans is limited. Potential risk based on animal studies. Use only if potential benefit justifies potential risk to the fetus. There are reports of poor neonatal adaptation (respiratory distress, seizures, temperature instability) with third-trimester exposure. Should not be used during pregnancy unless clearly needed and under specialist supervision.
Driving: May impair judgment, thinking, or motor skills. Patients should be cautioned about operating hazardous machinery, including automobiles, until they are reasonably certain that duloxetine therapy does not adversely affect their abilities.
| Monoamine Oxidase Inhibitors (MAOIs) - Phenelzine, Selegiline, Moclobemide | Risk of serotonin syndrome, hyperthermia, rigidity, autonomic instability. Potentially fatal. | Contraindicated |
| Other Serotonergic Drugs - SSRIs (Sertraline, Escitalopram), SNRIs (Venlafaxine), Tricyclics (Amitriptyline), Triptans (Sumatriptan), Tramadol, Fentanyl, Lithium, St. John's Wort | Increased risk of serotonin syndrome. | Major |
| Anticoagulants/Antiplatelets - Warfarin, NSAIDs (Ibuprofen, Aspirin), Clopidogrel | Increased risk of bleeding due to effect on platelet serotonin. | Major |
| CYP1A2 Inhibitors - Fluvoxamine, Ciprofloxacin, Enoxacin | Increased duloxetine plasma levels, increasing toxicity risk. | Moderate |
| CYP2D6 Inhibitors - Paroxetine, Fluoxetine, Quinidine | Increased duloxetine plasma levels. | Moderate |
| CYP1A2 Inducers - Smoking (tobacco), Omeprazole (mild) | Decreased duloxetine plasma levels, potentially reducing efficacy. | Moderate |
| Drugs Metabolized by CYP2D6 - Desipramine, Nortriptyline, Risperidone, Metoprolol | Duloxetine may increase plasma levels of these drugs. | Moderate |
| Antihypertensives | Potential attenuation of antihypertensive effect; monitor BP. | Moderate |