5-HT

Duloxetine ((S)-Duloxetine hydrochloride) (sold under the brand names Cymbalta, Ariclaim, Xeristar, Yentreve, Duzela, Dulane) is an SNRI (serotonin-norepinephrine reuptake inhibitor) that Eli Lilly makes and sells. It is recommended for both generalized anxiety disorder (GAD) and major depressive disorder. Moreover, duloxetine is approved for the treatment of musculoskeletal pain and osteoarthritis. Due to worries about liver toxicity and suicidal thoughts, duloxetine was not approved for this indication in the US; however, it was approved in Europe, where it is advised as a supplement to surgery in cases of stress urinary incontinence. It can also relieve the symptoms of painful peripheral neuropathy, particularly diabetic neuropathy, and it is used to control the symptoms of fibromyalgia. Duloxetine is mostly used to treat major depressive disorder, general anxiety disorder, stress-related urinary incontinence, painful peripheral neuropathy, fibromyalgia, chronic lower back pain, and musculoskeletal pain linked to osteoarthritis. Numerous other indications are being researched on it[1][2].

Oxaliplatin is a widely used chemotherapy agent, but induces serious peripheral neuropathy. Duloxetine is a dual reuptake inhibitor of serotonin and norepinephrine, and is shown to be effective against pain. However, whether and how duloxetine can attenuate oxaliplatin-induced allodynia in rodents is not clearly understood. A single injection of oxaliplatin (6 mg/kg, intraperitoneal; i.p.) induced a cold and mechanical allodynia, which was assessed by acetone and von Frey filament tests, respectively. When significant allodynic signs were observed, three different doses of duloxetine (10, 30, and 60 mg/kg, i.p.) were injected. Administration of 30 and 60 mg/kg of duloxetine significantly reduced the allodynia, whereas 10 mg/kg did not. By using an in vivo extracellular recording method, we further confirmed that 30 mg/kg of duloxetine could significantly inhibit the hyperexcitability of spinal wide dynamic range (WDR) cells. The anti-allodynic effect of duloxetine was completely blocked by an intrathecal injection of phentolamine (non-selective α-adrenergic receptor antagonist, 20 μg), or prazosin (α₁-adrenergic receptor antagonists, 10 μg); however, idazoxan (α₂-adrenergic receptor antagonist, 10 μg) did not block it. In conclusion, we suggest that duloxetine may have an effective protective action against oxaliplatin-induced neuropathic pain and spinal hyperexcitability, which is mediated by spinal α₁-adrenergic receptors[2].

Lactate Dehydrogenase Assay[1]
Lactate dehydrogenase (LDH) is an intracellular enzyme that is released to the supernatant during cell death. The LDH release into the incubation medium after cell membrane damage was measured using an LDH diagnostic kit according to manufacturer’s instructions. There were three repeats of each group for statistical analysis.[1]

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Lipid Peroxidation Assay[1]
The lipid peroxidation level was determined by measuring the concentration of malondialdehyde (MDA), which is the end product of lipid peroxidation and reacts with TBA to form a fluorescence adduct. The total MDA quantities were determined using a Lipid Peroxidation MDA Assay Kit according to manufacturer’s instructions. The total protein content was determined using the Pierce BCA Protein Assay Kit. The MDA level for each group was the total MDA divided by the total protein. There were three repeats of each group for statistical analysis.

Cell Viability Assay[1]
Cells were seeded in 96-well plates at a density of 2 × 105 cells per well, grown for 24 h, and then treated with the drugs according to time-dependence or dose-dependence protocols. Each treatment was conducted in triplicate. After the drug treatments, the cell viability was assayed using a Cell Counting Kit-8 (CCK-8) according to the manufacturer’s instructions. CCK-8 uses the sensitive colorimetric WST-8 assay to determine the number of viable cells. WST-8 is a highly water-soluble tetrazolium salt, with the chemical designation of 2-(2-methoxy-4-nitrophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium, monosodium salt.[1]

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Colony-Forming Assay[1]
N2a cells were treated with the various indicated concentrations of duloxetine for 24 h. Triplicate wells of 6-well plates containing 1 × 103 cells were treated with various concentrations of duloxetine and maintained for another 21 days. The colonies were fixed with methanol, stained with a 0.1% crystal violet solution in 1 h at room temperature, and counted. The colony formation assay was repeated three times.[1]

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N2a Cell Differentiation[1]
N2a cells were differentiated by a protocol that involved RA addition and serum withdrawal. The differentiation medium was DMEM supplemented with 20 μM RA, 100 U/ml penicillin and 100 μg/ml streptomycin. Neurites were identified as cell processes greater than two cell body diameters in length. Differentiated cells were defined as those bearing neurites. The percentage was statistically analyzed by counting 180 cells in six randomly chosen fields per well. The neurite length was defined as the distance from the cell body to the tips of the neurites. The length of the longest neurite was measured in at least 50 cells in five randomly chosen fields using the ImageJ software. To evaluate the cell toxicity, N2a cells that were committed to differentiation with RA were treated with the addition of 12.5 μM duloxetine or 12.5 μM duloxetine plus 10 μM rifampicin for 24 h. Statistical comparisons of the cell morphology were conducted between control, RA, RA + duloxetine and RA + duloxetine + rifampicin groups after a 24-h treatment (n = 3). The cell viability and cell morphology were recorded each day during the full differentiation period (n = 3). Furthermore, the events associated with cell cycle and cell death were analyzed at various time points in the control and RA groups to permit interpretation of the key changes during the N2a cell differentiation. Statistical analyses of cell death (n = 4), cell cycle (n = 4) and biochemical changes (n = 3) were conducted in the control, RA, RA + duloxetine groups after the 24-h treatment.

Duloxetine and α-Adrenergic Receptor Antagonists Administration[2]
Duloxetine was dissolved in distilled water (D.W.). Different doses of duloxetine (10, 30, and 60 mg/kg) were administered (i.p.). To test which adrenergic receptor subtypes mediated the anti-allodynic effects of duloxetine in oxaliplatin-administered mice, antagonists were administered intrathecally 20 min prior to duloxetine treatments. Non-selective α-adrenergic antagonists (phentolamine, 20 μg), α1-adrenergic receptor antagonists (prazosin, 10 μg), and α2-adrenergic receptor antagonists (idazoxan, 10 μg) were administered in volumes of 5 μL. The dose of each antagonist was determined based on previously conducted studies showing the selective and effective antagonistic action against adrenergic receptor-mediated responses.[2]

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In Vivo Extracellular Recording[2]
Extracellular recordings were made from Sprague-Dawley rats, three to five days after the administration of oxaliplatin, when rats exhibited significant mechanical and cold allodynia. Extracellular recordings were carried out as previously described. In brief, rats were anesthetized with urethane (1.5 g/kg, i.p.). The spinal cords of the animals, which were fixed in a stereotaxic frame, was exposed from T13–L2 and irrigated with oxygenated (95% O2-5% CO2 gas) Krebs solution (in mM: 117 NaCl, 3.6 KCl, 2.5 CaCl2, 1.2 MgCl2, 1.2 NaH2PO4, 11 glucose, and 25 NaHCO3) at a flow rate of 10–15 mL/min at 38 ± 1 °C. Based on their responses to brush, pressure, pinch, and acetone stimulations, the WDR cells were classified. Extracellular single-unit recordings were made with a low-impedance insulated tungsten microelectrode (impedance of 10 MΩ). For mechanical stimuli, brush, press, and pinch stimulations were applied to the lateral and ventral surfaces of the hind paw. Brush stimulus was given by brushing the receptive field five times with a camel brush. Press stimulus was given by pressing the receptive field for 4 s using the blunt tip of the camel brush with a diameter of 0.5 cm and a magnitude of about 20 g. Pinch stimulation was given by pinching the skin using toothed forceps for 3 s. For cold stimulation, 10 μL of acetone drop was applied to the receptive fields.

Effects During Pregnancy and Lactation
◉ Overview of Use During Lactation
Limited information exists regarding the use of duloxetine during lactation; however, low concentrations of the drug in breast milk and serum drug concentrations were observed in two breastfed infants. Breastfeeding does not need to be discontinued if the mother requires duloxetine. Expert opinion considers the use of duloxetine during lactation acceptable, and safety rating systems indicate that cautious use of duloxetine during lactation is feasible. Especially when breastfeeding newborns or premature infants, a more well-studied alternative may be preferred. Infant drowsiness, feeding, weight gain, and developmental milestones should be monitored, especially in younger exclusively breastfed infants and when using concurrent psychiatric medications. Women taking duloxetine have reported galactorrhea.
◉ Effects on Breastfed Infants
One part-feeding mother took duloxetine 90 mg and extended-release methylphenidate (Concerta) 36 mg daily for the treatment of attention deficit hyperactivity disorder, generalized anxiety disorder, borderline personality disorder, and depression. She part-feeded her infant (dosage not specified) for approximately 1 month. At 6 months of age, the infant was developing normally, except for recurrent pneumonia caused by a congenital airway malformation. Another mother took duloxetine 60 mg daily while part-feeding her infant (dosage not specified). No adverse reactions were observed in the infant at 6 weeks of age.
One mother reported that her infant experienced drowsiness as an adverse reaction in the first few weeks after birth. She was taking agomelatine (dosage not specified) and duloxetine 90 mg concurrently. She attributed the drowsiness to agomelatine and continued breastfeeding until the infant was 9 months of age. At follow-up, she reported some problems with the infant's language development and hypotonia.
◉ Effects on Lactation and Breast Milk
In a small prospective study, eight primiparous women taking selective serotonin reuptake inhibitors (SRIs; three taking fluoxetine, and one taking citalopram, duloxetine, escitalopram, paroxetine, or sertraline, respectively) were compared with 423 mothers not taking SRIs. Mothers taking SRIs experienced a mean delay of 16.7 hours initiation of lactation activation (stage II) compared to the control group (85.8 hours postpartum in the SRI treatment group vs. 69.1 hours postpartum in the untreated group), which doubled the risk of delayed feeding behavior. However, the delay in stage II lactation may not have been clinically significant, as there was no statistically significant difference between the two groups in the proportion of mothers experiencing feeding difficulties after day 4 postpartum.
One non-pregnant woman experienced elevated serum prolactin levels and a recurrence of galactorrhea symptoms that had previously decreased upon discontinuation of venlafaxine after starting duloxetine. After discontinuing duloxetine, her prolactin levels returned to normal, and the galactorrhea stopped. A woman taking duloxetine (dosage unknown) for depression reported a milky discharge from her nipples. She had not experienced this side effect while taking antidepressants previously. Her serum prolactin levels were elevated, and a head MRI showed no tumors. After discontinuing duloxetine, she received a one-month treatment with 20 mg escitalopram daily and 0.5 mg cabergoline weekly. At this time, her serum prolactin levels returned to normal, and the galactorrhea stopped. In a study of cases of hyperprolactinemia and its symptoms (e.g., gynecomastia) reported by the French National Center for Drug Vigilance, duloxetine did not increase the risk of hyperprolactinemia compared to other drugs. A woman taking 60 mg of duloxetine for depression experienced milky discharge, breast engorgement, and breast pain after 10 weeks of treatment. After discontinuing duloxetine, she started taking bupropion. Two weeks after discontinuing duloxetine, her galactorrhea symptoms improved. Six weeks after discontinuing duloxetine, her serum prolactin level decreased from 37.9 mcg/L to 20.2 mcg/L. Her galactorrhea was likely caused by duloxetine. A woman receiving duloxetine 30 mg daily for migraines began experiencing bilateral galactorrhea in the tenth week of treatment. At that time and in subsequent measurements, her serum prolactin levels were within the normal range. Three days after discontinuing duloxetine, her galactorrhea symptoms disappeared. The authors believe her galactorrhea was likely caused by duloxetine. An observational study investigated pregnancy outcomes in 2859 women who took antidepressants for two years prior to pregnancy. Compared to women who did not take antidepressants during pregnancy, mothers who took antidepressants throughout all three stages of pregnancy were 37% less likely to breastfeed at discharge. Mothers who took antidepressants only in the third trimester were 75% less likely to breastfeed at discharge. Mothers who took antidepressants only in the first and second trimesters were not less likely to breastfeed at discharge. The study did not specify the type of antidepressant used by the mothers. A retrospective cohort study analyzed hospital electronic medical records from 2001 to 2008, comparing women who took antidepressants in late pregnancy (n = 575), women with mental illness but not taking antidepressants (n = 1552), and mothers not diagnosed with mental illness (n = 30,535). Women treated with antidepressants were 37% less likely to breastfeed at discharge than women not diagnosed with mental illness, but there was no difference in the likelihood of breastfeeding compared to untreated mothers diagnosed with mental illness. None of the mothers were taking duloxetine. One woman with major depressive disorder was treated with duloxetine at a dose of 40 mg twice daily. Two weeks later, she experienced menstrual irregularities and nipple discharge. Her serum prolactin level increased to 205 μg/L. Duloxetine's dose was reduced to 60 mg once daily, and aripiprazole was started, with the dose gradually increased from 2.5 mg daily to 5 mg daily. Within two weeks, the galactorrhea symptoms disappeared, and serum prolactin levels dropped to 118 μg/L. Six weeks later, serum prolactin levels were 39 μg/L. This combination therapy regimen was continued for 39 weeks without further galactorrhea symptoms.
A 16-year-old girl was hospitalized for depression and a suicide attempt. She had previously experienced galactorrhea while taking risperidone and escitalopram. After admission, she started taking duloxetine at 20 mg daily, which was increased to 40 mg daily after 5 days. Two days later, a small amount of milk appeared in her right breast. Her serum prolactin level was slightly elevated at 26 μg/L. Milk production stopped after the dose was reduced to 20 mg daily.
A woman with depression received duloxetine treatment at 30 mg daily for one month, then increased to 60 mg daily. After four months of treatment, she developed amenorrhea, galactorrhea, and hyperprolactinemia. The patient received cabergoline 0.5 mg twice weekly and discontinued duloxetine. One month later, her serum prolactin levels returned to normal. A woman with multiple sclerosis was taking duloxetine 60 mg daily for three months due to pain and depression. She noticed milky discharge within a month and elevated serum prolactin levels. Duloxetine was changed to escitalopram 10 mg daily. Within a few days, her galactorrhea stopped, and her serum prolactin levels decreased. After ruling out other causes of hyperprolactinemia, she started taking cabergoline 0.25 mg twice weekly. After three months, the dosage was reduced, and her serum prolactin levels remained normal. A study of 80,882 Norwegian mother-infant pairs between 1999 and 2008 showed that 392 women reported starting antidepressant use postpartum, and 201 women reported starting antidepressant use during pregnancy. Compared to a control group unexposed to antidepressants, antidepressant use in late pregnancy reduced the rate of breastfeeding initiation by 7%, but had no effect on the duration of breastfeeding or the rate of exclusive breastfeeding. Compared to a control group unexposed to antidepressants, recent use or re-initiation of antidepressant use reduced the rate of primary breastfeeding at 6 months by 63%, the rate of breastfeeding in any form by 51%, and increased the risk of abrupt cessation of breastfeeding by 2.6 times. Specific antidepressants were not mentioned in the study.

[1]. Dose-dependent noradrenergic and serotonergic properties of venlafaxine in animal models indicative of antidepressant activity. Psychopharmacology (Berl). 1998 Jul;138(1):1-8.

[2]. Desvenlafaxine succinate: A new serotonin and norepinephrine reuptake inhibitor. J Pharmacol Exp Ther. 2006 Aug;318(2):657-65. Epub 2006 May 4.

(S)-Duloxetine hydrochloride is a duloxetine hydrochloride in which the duloxetine portion has an S-configuration. It is an antidepressant. It contains (S)-duloxetine. Duloxetine hydrochloride is the hydrochloride salt of duloxetine, a highly bioavailable orally bioavailable fluoxetine derivative belonging to the class of selective serotonin (5-HT) and norepinephrine (NE) reuptake inhibitors (SNRIs), possessing central analgesic, anxiolytic, and antidepressant activities. After oral administration, duloxetine selectively blocks the reuptake of 5-HT and NE by transport complexes on the presynaptic membrane, thereby increasing the levels of these neurotransmitters in the synaptic cleft. This product can enhance serotonergic and norepinephrine activity in the central nervous system (CNS), relieving symptoms of anxiety, depression, and neuropathic disorders, such as neuropathic pain. This product is a thiophene derivative and is a selective serotonin and norepinephrine reuptake inhibitor (SNRI). It is an antidepressant and anti-anxiety medication, also used to treat pain in patients with diabetes and fibromyalgia.
See also: Duloxetine (containing the active ingredient).

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Drug Indications
For the treatment of major depressive disorder; for the treatment of diabetic peripheral neuropathy; for the treatment of generalized anxiety disorder; Duloxetine Mylan is indicated for adults.
For the treatment of major depressive disorder. For the treatment of diabetic peripheral neuropathy. For the treatment of generalized anxiety disorder. Duloxetine (Cymbalta) is indicated for adults.
Yentreve is indicated for women for the treatment of moderate to severe stress urinary incontinence (SUI).
Lilly's Duloxetine (Duloxetine Lilly) is indicated for adults for the treatment of: major depressive disorder, diabetic peripheral neuropathy, and generalized anxiety disorder.
Lilly's Duloxetine (Duloxetine Lilly) is indicated for adults.
For the treatment of diabetic peripheral neuropathy.
Ariclaim is indicated for adults.
For the treatment of diabetic peripheral neuropathy in adults.
Treatment for chronic pain, diabetic neuropathic pain, generalized anxiety disorder, major depressive disorder, and stress urinary incontinence.

C18H20CLNOS

333.88

333.095

C, 64.75; H, 6.04; Cl, 10.62; N, 4.20; O, 4.79; S, 9.60

136434-34-9

Duloxetine; 116539-59-4; Duloxetine-d3 hydrochloride; 1435727-97-1; (±)-Duloxetine hydrochloride; 947316-47-4; Duloxetine metabolite Para-Naphthol Duloxetine; 949095-98-1

60834

White to off-white solid powder

466.2ºC at 760 mmHg

118-122ºC

235.7ºC

5.823

2

3

6

22

312

1

Cl[H].S1C([H])=C([H])C([H])=C1[C@]([H])(C([H])([H])C([H])([H])N([H])C([H])([H])[H])OC1=C([H])C([H])=C([H])C2=C([H])C([H])=C([H])C([H])=C12

BFFSMCNJSOPUAY-LMOVPXPDSA-N

InChI=1S/C18H19NOS.ClH/c1-19-12-11-17(18-10-5-13-21-18)20-16-9-4-7-14-6-2-3-8-15(14)16;/h2-10,13,17,19H,11-12H2,1H3;1H/t17-;/m0./s1

(3S)-N-methyl-3-naphthalen-1-yloxy-3-thiophen-2-ylpropan-1-amine;hydrochloride

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Note: Please store this product in a sealed and protected environment, avoid exposure to moisture.

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Solubility in Formulation 1: ≥ 2.5 mg/mL (7.49 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: ≥ 2.5 mg/mL (7.49 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

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Solubility in Formulation 3: ≥ 2.5 mg/mL (7.49 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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Solubility in Formulation 4: 2% DMSO +30% PEG 300 +ddH2O: 30mg/mL

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Solubility in Formulation 5: 140 mg/mL (419.31 mM) in PBS (add these co-solvents sequentially from left to right, and one by one), clear solution; with ultrasonication.

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 (Please use freshly prepared in vivo formulations for optimal results.)