Actions of Naxdu in details
Pharmacology: Naxdu HCl is a selective serotonin and norepinephrine reuptake inhibitor (SSNRI).
Mechanism of Action: Although the exact mechanism of the antidepressant and central pain inhibitory action of Naxdu in humans are unknown, the antidepressant and pain inhibitory actions are believed to be related to its potentiation of serotonergic and noradrenergic activity in the central nervous system (CNS). Preclinical studies have shown that Naxdu is a potent inhibitor of neuronal serotonin and norepinephrine reuptake and a less potent inhibitor of dopamine reuptake. Naxdu has no significant affinity for dopaminergic, adrenergic, cholinergic, histaminergic, opioid, glutamate and GABA receptors in vitro. Naxdu does not inhibit monoamine oxidase (MAO). Naxdu undergoes extensive metabolism, but the major circulating metabolites have not been shown to contribute significantly to the pharmacologic activity of Naxdu.
Pharmacokinetics: Naxdu is well absorbed after oral administration, with maximal plasma concentrations of Naxdu (Cmax) occurring 6 hrs post-dose. The absolute oral bioavailability of Naxdu ranged from 32-80%. Food does not affect the Cmax of Naxdu, but delays the time to reach peak concentration from 6-10 hrs and it marginally decreases the extent of absorption (AUC) by about 10%. There is a 3-hr delay in absorption and a 1/3 increase in apparent clearance of Naxdu after an evening dose as compared to a morning dose. Steady-state plasma concentrations are typically achieved after 3 days of dosing.
The apparent volume of distribution averages about 1640 L. Naxdu is highly bound (>90%) to proteins in human plasma, binding primarily to albumin and α1-acid glycoprotein. Plasma protein binding of Naxdu is not affected by renal or hepatic impairment.
Elimination of Naxdu is mainly through hepatic metabolism involving 2 P450 isozymes, CYP2D6 and CYP1A2. Naxdu has an elimination half-life (t½) of about 12 hrs (range 8-17 hrs) and its pharmacokinetics are dose proportional over the therapeutic range. Biotransformation and disposition of Naxdu in humans have been determined following oral administration of 14C-labeled Naxdu. Naxdu comprises about 3% of the total radiolabeled material in the plasma, indicating that it undergoes extensive metabolism to numerous metabolites. The major biotransformation pathways for Naxdu involve oxidation of the naphthyl ring followed by conjugation and further oxidation. Both CYP2D6 and CYP1A2 catalyze the oxidation of the naphthyl ring in vitro. Metabolites found in plasma include 4-hydroxy Naxdu glucuronide and 5-hydroxy, 6-methoxy Naxdu sulfate. Many additional metabolite have been identified in urine, some representing only minor pathways of elimination. Only trace (<1% of the dose) amounts of unchanged Naxdu are present in the urine. Most (about 70%) of the Naxdu dose appears in the urine as metabolites of Naxdu: About 20% is excreted in the feces.
Naxdu bioavailability (AUC) appears to be reduced by about 1/3 in smokers. Dosage modifications are not recommended for smokers. After a single Naxdu 60 mg dose, Cmax and AUC values were approximately 100% greater in patients with end stage renal disease receiving chronic intermittent hemodialysis than in subjects with normal renal function. The AUCs of the major circulating metabolites were approximately 7- to 9-fold higher and would be expected to increase further with multiple dosing. For this reason, Naxdu is not recommended for patients with end stage renal disease (requiring dialysis) or severe renal impairment [estimated creatinine clearance (CrCl) <30 mL/min].
Patients with clinically evident hepatic insufficiency have decreased Naxdu metabolism and elimination. After a single Naxdu 20 mg dose, 6 cirrhotic patients with moderate liver impairment (Child-Pugh class B) had a mean plasma Naxdu clearance about 15% that of age and gender matched healthy subjects, with a 5-fold increase in mean exposure (AUC). Although Cmax was similar to normals in the cirrhotic subjects, the t½ was about 3 times longer.
How should I take Naxdu?
Take Naxdu only as directed by your doctor to benefit your condition as much as possible. Do not take more of it, do not take it more often, and do not take it for a longer time than your doctor ordered.
Naxdu comes with a Medication Guide. Read and follow the instructions carefully. Ask your doctor if you have any questions.
Swallow the delayed-release capsule whole with or without food. Do not chew, crush, or break the capsule. Do not open the capsule and sprinkle the contents on food or in liquids.
You will need to use Naxdu for several weeks before you begin to feel better. Keep using the medicine even if you feel you are not getting better, and talk to your doctor if you have any questions.
Dosing
The dose of Naxdu will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of Naxdu. If your dose is different, do not change it unless your doctor tells you to do so.
The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.
- For oral dosage form (delayed-release capsules):
- For treatment of anxiety:
- Adults—At first, 60 milligrams (mg) once a day. Some patients may start at 30 mg once a day for 1 week before increasing the dose to 60 mg once a day. Your doctor may increase your dose as needed. However, the dose is usually not more than 120 mg per day.
- Elderly—At first, 30 mg once a day for 2 weeks before increasing the dose to 60 mg once a day. Your doctor may increase your dose as needed. However, the dose is usually not more than 120 mg per day.
- Children 7 years of age and older—At first, 30 mg once a day for 2 weeks before increasing the dose to 60 mg once a day. Your doctor may increase your dose as needed. However, the dose is usually not more than 120 mg per day.
- Children younger than 7 years of age—Use and dose must be determined by your doctor.
- For treatment of chronic muscle pain:
- Adults—60 milligrams (mg) once a day. Some patients may start at 30 mg once a day for 1 week before increasing the dose to 60 mg once a day.
- Children—Use and dose must be determined by your doctor.
- For treatment of depression:
- Adults—40 milligrams (mg) per day (given as 20 mg two times per day) to 60 mg per day (given either once a day or as 30 mg two times per day). Your doctor may increase your dose as needed. However, the dose is usually not more than 120 mg per day.
- Children—Use and dose must be determined by your doctor.
- For treatment of diabetic peripheral neuropathy:
- Adults—60 milligrams (mg) once a day.
- Children—Use and dose must be determined by your doctor.
- For treatment of fibromyalgia:
- Adults—60 milligrams (mg) once a day. Some patients may start at 30 mg once a day for 1 week before increasing the dose to 60 mg once a day.
- Children—Use and dose must be determined by your doctor.
- For treatment of anxiety:
Missed Dose
If you miss a dose of Naxdu, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.
Storage
Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.
Keep out of the reach of children.
Do not keep outdated medicine or medicine no longer needed.
Ask your healthcare professional how you should dispose of any medicine you do not use.
Naxdu administration
Oral: Administer without regard to meals. Swallow capsule whole; do not crush or chew.
Delayed-release particles capsule: Although the manufacturer does not recommend opening the capsule to facilitate administration, Naxdu has been found to be stable for up to 2 hours after sprinkling the contents of capsule on applesauce or in apple juice (not chocolate pudding) taking care not to crush the pellets and damage the enteric coating (Wells 2008). Tolerability studies of this administration technique have not been conducted. Adverse effects have been reported to the FDA when patients opened the capsules, however, reports do not detail if pellets were crushed (FDA 2007).
Delayed-release sprinkle capsule: Capsule can be opened and contents sprinkled over small amount of applesauce; instruct patient to swallow drug/food mixture immediately after mixing. Contents of capsule can also be added to a plastic catheter tip syringe with 50 mL of water and shaken for 10 seconds before administering through a 12 French or larger nasogastric tube.
Naxdu pharmacology
Mechanism of Action
Although the exact mechanisms of the antidepressant, central pain inhibitory and anxiolytic actions of Naxdu in humans are unknown, these actions are believed to be related to its potentiation of serotonergic and noradrenergic activity in the CNS.
Pharmacodynamics
Preclinical studies have shown that Naxdu is a potent inhibitor of neuronal serotonin and norepinephrine reuptake and a less potent inhibitor of dopamine reuptake. Naxdu has no significant affinity for dopaminergic, adrenergic, cholinergic, histaminergic, opioid, glutamate, and GABA receptors in vitro. Naxdu does not inhibit monoamine oxidase (MAO).
Naxdu is in a class of drugs known to affect urethral resistance. If symptoms of urinary hesitation develop during treatment with Naxdu, consideration should be given to the possibility that they might be drug-related.
Pharmacokinetics
Naxdu has an elimination half-life of about 12 hours (range 8 to 17 hours) and its pharmacokinetics are dose proportional over the therapeutic range. Steady-state plasma concentrations are typically achieved after 3 days of dosing. Elimination of Naxdu is mainly through hepatic metabolism involving two P450 isozymes, CYP1A2 and CYP2D6.
Absorption and Distribution
Orally administered Naxdu hydrochloride is well absorbed. There is a median 2 hour lag until absorption begins (Tlag), with maximal plasma concentrations (Cmax) of Naxdu occurring 6 hours post dose. Food does not affect the Cmax of Naxdu, but delays the time to reach peak concentration from 6 to 10 hours and it marginally decreases the extent of absorption (AUC) by about 10%. There is a 3 hour delay in absorption and a one-third increase in apparent clearance of Naxdu after an evening dose as compared to a morning dose.
The apparent volume of distribution averages about 1640 L. Naxdu is highly bound (>90%) to proteins in human plasma, binding primarily to albumin and α1-acid glycoprotein. The interaction between Naxdu and other highly protein bound drugs has not been fully evaluated. Plasma protein binding of Naxdu is not affected by renal or hepatic impairment.
Metabolism and Elimination
Biotransformation and disposition of Naxdu in humans have been determined following oral administration of 14C-labeled Naxdu. Naxdu comprises about 3% of the total radiolabeled material in the plasma, indicating that it undergoes extensive metabolism to numerous metabolites. The major biotransformation pathways for Naxdu involve oxidation of the naphthyl ring followed by conjugation and further oxidation. Both CYP1A2 and CYP2D6 catalyze the oxidation of the naphthyl ring in vitro. Metabolites found in plasma include 4-hydroxy Naxdu glucuronide and 5-hydroxy, 6-methoxy Naxdu sulfate. Many additional metabolites have been identified in urine, some representing only minor pathways of elimination. Only trace (<1% of the dose) amounts of unchanged Naxdu are present in the urine. Most (about 70%) of the Naxdu dose appears in the urine as metabolites of Naxdu; about 20% is excreted in the feces. Naxdu undergoes extensive metabolism, but the major circulating metabolites have not been shown to contribute significantly to the pharmacologic activity of Naxdu.
Children and Adolescents (ages 7 to 17 years)
Naxdu steady-state plasma concentration was comparable in children (7 to 12 years of age), adolescents (13 to 17 years of age) and adults. The average steady-state Naxdu concentration was approximately 30% lower in the pediatric population (children and adolescents) relative to the adults. The model-predicted Naxdu steady state plasma concentrations in children and adolescents were mostly within the concentration range observed in adult patients and did not exceed the concentration range in adults.
References
- EPA DSStox. "Duloxetine: DSSTox provides a high quality public chemistry resource for supporting improved predictive toxicology.". https://comptox.epa.gov/dashboard/ds... (accessed September 17, 2018).
Reviews
The results of a survey conducted on ndrugs.com for Naxdu are given in detail below. The results of the survey conducted are based on the impressions and views of the website users and consumers taking Naxdu. We implore you to kindly base your medical condition or therapeutic choices on the result or test conducted by a physician or licensed medical practitioners.User reports
Consumer reported administration
No survey data has been collected yetConsumer reviews
There are no reviews yet. Be the first to write one! |
Information checked by Dr. Sachin Kumar, MD Pharmacology
