Amitriptyline

Chemical Properties and Structure of Amitriptyline

This compound (3-(10,11-dihydro-5H-dibenzo[a,d]annulen-5-ylidene)-N,N-dimethylpropan-1-amine) [C20H23N] is a small molecule with a molecular weight of 277.41 Da. It is a tertiary amine tricyclic compound with no hydrogen bond donors and a single hydrogen bond acceptor. As a highly lipophilic molecule, this compound has an octanol-water partition coefficient (pH 7.4) of 3.0, while the log P of the free base was reported as 4.92. The solubility of the free base this compound in water is 14 mg/L.

The structure of this compound features a tricyclic system with a seven-membered central ring containing an exocyclic double bond. This double bond is a key structural element that distinguishes this compound from other related compounds and affects its synthetic pathways.

Traditional Synthesis Methods from Dibenzosuberone

Primary Synthesis Route

The original patent literature describes two main routes for the synthesis of this compound starting from dibenzosuberone. In the first synthesis route, dibenzosuberone (4) undergoes a reaction with the Grignard reagent (5) derived from dimethylaminopropyl chloride to yield the tertiary alcohol (6). Compound 6 is then dehydrated to this compound (2) using acidic conditions.

This method can be summarized as follows:

• Reaction of dibenzosuberone with 3-(dimethylamino)propylmagnesium chloride
• Formation of the tertiary alcohol intermediate
• Dehydration of the tertiary alcohol using acidic conditions to form this compound

Alternative Synthesis Route

An alternative synthesis was also reported in which dibenzosuberone (4) undergoes a reaction with the Grignard reagent (7) derived from cyclopropyl bromide to yield the tertiary alcohol (8). This intermediate can then be further processed to yield this compound. This alternative approach provides synthetic flexibility and may offer advantages depending on reagent availability and reaction conditions.

Synthesis Methods for Key Intermediates

Traditional Methods for o-Phenethyl Benzoic Acid

o-Phenethyl benzoic acid (also referred to as adjacent styroyl phenylformic acid) is an important intermediate in the synthesis of this compound hydrochloride. Several methods have been developed for its preparation, each with distinct advantages and limitations.

One traditional method, described by Roberts, P.J. and Castar, J. in Cyclobenzaprine.DrugsFut1977, uses benzal phthalide as the starting material, with red phosphorus as a catalyst. The reaction involves back flow in hydroiodic acid solution to directly obtain o-phenethyl benzoic acid. However, this method has significant environmental drawbacks: it uses red phosphorus which causes severe pollution, produces large volumes of wastewater, requires a reaction time of 48 hours, and yields only 80% product.

Another traditional method described by Vilani, F.J. in 5-(3-Dimethylamino-2-methylpropyl) dizenzocycloheptenes.US3409640 also starts with benzal phthalide, obtains adjacent phenylacetyl sodium benzoate through hydrolysis, and then uses palladium carbon as a catalyst to obtain o-phenethyl benzoic acid. This method employs high-temperature (>100 degrees Celsius) high-pressure (>20 kilograms per square centimeter) hydrogenation, which creates operational dangers. Additionally, the reaction yield is only 88%, and the product purity is less than 94%.

Improved Low-Temperature Low-Pressure Method

A recent patent discloses an improved preparation method for o-phenethyl benzoic acid that overcomes the limitations of high-temperature high-pressure hydrogenation. This method implements low-temperature low-pressure hydrogenation, significantly enhancing synthesis yield and product purity.

The detailed procedure follows these steps:

• In a dried and clean autoclave, sequentially add sodium o-phenylacetyl benzoate, purified water, and a special-purpose catalyst in a weight ratio of 1:4:0.02
• Close the autoclave and displace the air with pressure nitrogen gas
• After thorough displacement, introduce hydrogen at a pressure of 5 kilograms per square centimeter
• Start stirring while warming up to 40 degrees Celsius and carry out hydrogenation
• When the temperature rises to 50 degrees Celsius, open the water coolant
• Maintain hydrogen pressure at 2-4 kilograms per square centimeter
• Stop introducing hydrogen and sample to detect material content
• When material content is less than 0.1%, release and discharge the reaction mixture
• Filter the mixture and adjust pH to 1-2 with reagent hydrochloric acid
• Filter again and dry until the moisture content is less than 0.5%
• The final product, o-phenethyl benzoic acid, is obtained with a yield of 98% and purity greater than 99%

The special-purpose catalyst used in this method comprises:

• 90-99% nano nickel
• 0.3-3.0% cobalt
• 0.2-2.0% aluminum
• 0.3-2.0% iron
• 0.2-2.0% silicon

This innovative approach significantly improves the reaction metrics compared to traditional methods:

• Maximum reaction temperature is lowered from 100 degrees Celsius to 50 degrees Celsius
• Hydrogenation pressure is lowered from 20 kilograms per square centimeter to 5 kilograms per square centimeter
• Product yield is enhanced from 88% to 98%
• Product purity is enhanced from 94% to 99%

Modern Flow Chemistry Approaches

Continuous Flow Protocol with Multilithiation

Recent advances in synthetic chemistry have led to the development of continuous flow protocols for the preparation of this compound. These methods offer several advantages over traditional batch procedures, particularly when handling highly reactive intermediates and gaseous reagents.

A notable continuous flow protocol involves multiple organolithium generation. In this method, three different lithium-halogen exchange reactions take place with precise timing, each initiating carbon-carbon bond formation. The process features continuous multilithiation combined with carboxylation and the Parham cyclization, a Grignard addition, and thermolytic water elimination by inductive heating.

The detailed procedure for this multistep synthesis is as follows:

• Lithiation and Carboxylation :

  • The first lithiation reaction between benzyl bromide (11) and n-butyllithium is performed in a 0.5 milliliter steel reactor coil (inner diameter = 1.0 millimeter) at -50 degrees Celsius
  • Upon quenching with methanol, the desired aryl bromide is obtained

• Grignard Reaction :

  • The aryl bromide is reacted with a Grignard reagent (14) in a 0.5 milliliter perfluoroalkoxy alkane reactor coil (inner diameter = 1.0 millimeter) at 25 degrees Celsius with a residence time of about 30 seconds
  • The crude reaction mixture is protonated with ethanol to form the carbinol intermediate (15)

• Water Elimination :

  • The carbinol (15) undergoes water elimination using inductive heating technology
  • A 0.3 milliliter cartridge steel reactor (inner diameter = 4.0 millimeters) filled with steel beads (inner diameter = 0.8 millimeters) is encased in a high-frequency field (810 Hz)
  • After 30 seconds of residence time at 200 degrees Celsius, the starting material is completely converted into this compound
  • A heat exchanger cools the crude mixture to room temperature

• Salt Formation :

  • Addition of hydrochloric acid (1 molar solution in isopropanol) followed by recrystallization from ethanol/diethyl ether mixture yields this compound hydrochloride salt (16) in 71% overall yield

This continuous flow protocol demonstrates the advantages of flow chemistry in handling organometallic agents and performing reactions with gases. The multistep protocol combines continuous multilithiation with carboxylation, the Parham cyclization, a Grignard addition, and thermolytic water elimination, all key features that would be challenging to implement in a traditional batch process.

Multi-Step Synthesis from 2-Bromobenzyl Bromide

Another modern approach to the synthesis of this compound hydrochloride involves a multi-step reaction starting from 2-bromobenzyl bromide. This method, documented in ChemicalBook, consists of four distinct steps:

• Reaction with n-butyllithium and carbon dioxide in tetrahydrofuran and hexane at -50 to 20 degrees Celsius under 3878.71 Torr pressure in a flow reactor
• Treatment with methanol in tetrahydrofuran and toluene at 20 degrees Celsius in a flow reactor
• Reaction in ethanol at 200 degrees Celsius under 82508.3 Torr pressure for 0.01 hours in a flow reactor
• Final reaction with hydrogen chloride in isopropyl alcohol at 20 degrees Celsius in a flow reactor

This method exemplifies the trend toward more streamlined, efficient synthesis routes that can be implemented in continuous flow systems. The approach provides better control over reaction parameters and safer handling of hazardous intermediates, which is particularly important for industrial-scale production.

Preparation of this compound Hydrochloride for Pharmaceutical Use

Standard Solution Preparation

For pharmaceutical applications, the preparation of this compound hydrochloride must meet stringent purity requirements. The United States Pharmacopeia provides guidelines for the preparation and analysis of this compound hydrochloride formulations.

For analytical purposes, a standard solution of this compound hydrochloride can be prepared as follows:

• Dissolve an appropriate amount of United States Pharmacopeia this compound Hydrochloride Reference Standard in a suitable diluent
• Dilute to obtain a final concentration of 2 micrograms per milliliter
• This standard solution can be used for chromatographic analysis and quality control testing

Topical Formulation Preparation

For topical applications, this compound hydrochloride can be compounded with various bases. A recent study investigated formulations with Lipoderm base, Emollient Cream, and Mediflo 30 pluronic lecithin organogel gel at concentrations of 1%, 5%, and 10%.

The detailed procedure for preparing these topical formulations is as follows:

• Weigh an appropriate amount of this compound hydrochloride and triturate to produce a fine powder using mortar and pestle
• Add the required amount of ethoxy diglycol to the fine powder and levitate to produce a smooth paste
• Add each base to the prepared paste using the principles of geometric dilution
• Transfer the cream to a jar and mix using an electronic mortar and pestle
• Process once through an ointment mill
• Place the resulting formulation in appropriate containers for storage

The release of this compound from these bases and subsequent permeation across artificial human skin were investigated with the Franz diffusion system. The study found that the drug release mechanisms and permeation characteristics varied depending on the base used, providing valuable information for the development of topical formulations for neuropathic pain.

Comparative Analysis of Synthesis Methods

Table 1. Comparison of Different Synthesis Methods for this compound and Its Intermediates

This comprehensive comparison highlights the evolution of synthesis methods for this compound and its intermediates, demonstrating a clear trend from traditional batch processes with significant drawbacks to modern approaches that offer improved yields, purity, safety profiles, and environmental compatibility. The table also reveals the trade-offs between simpler processes with environmental concerns versus more complex setups that provide better outcomes.

Recent Developments in this compound Formulation

Multicomponent Crystals for Controlled Release

Researchers have developed novel multicomponent crystals of this compound as potential controlled-release systems. Six novel multicomponent crystals, including three salts with dicarboxylic acid counterions, two salt cocrystals, and a salt hydrate, have been obtained and structurally characterized by single-crystal X-ray diffraction analysis.

The structural analysis revealed that all investigated crystals contain two-dimensional bilayers of this compound cations separated by organic counterions, with significant differences in the packing arrangements of this compound cations within the bilayers. This structural diversity offers opportunities for tailoring dissolution profiles and drug release characteristics.

The dissolution performance of these solid forms was studied in the fasted state simulated gastric fluid buffer solution under sink conditions and compared to the commercial form of this compound hydrochloride. The potential of this compound maleate and this compound oxalate salts as a basis for designing controlled-release forms was highlighted in this research.

Analytical Methods for Quality Control

Several analytical methods have been developed for the quantitative determination of this compound hydrochloride in bulk and pharmaceutical formulations:

A simple, rapid, reliable, and accurate High-Performance Thin-Layer Chromatography (HPTLC) method has been developed for the quantitative determination of this compound hydrochloride in bulk and tablets. The method uses a mobile phase with methanol, toluene, acetone, and ammonia, and densitometric scanning is performed at 254 nanometers.

Five spectrophotometric methods for the determination of this compound hydrochloride have also been developed, validated, and applied for the assay of the drug in pharmaceutical formulations. These methods include reaction with iodine in 1,2-dichloroethane and oxidation with alkaline potassium permanganate to produce manganate ion which absorbs at 610 nanometers.

The literature survey reveals that this compound undergoes oxidation at the exocyclic double bond and gives rise to dibenzosuberone, which forms the basis for some of these analytical methods.

Grignard Reaction Pathway

The traditional synthesis involves:

• Reactants : Dibenzosuberane and 3-(dimethylamino)propylmagnesium chloride.

• Reaction Conditions :

  • Heating with hydrochloric acid to eliminate water.

  • Forms the tricyclic structure via cyclization .

• Catalytic Improvements :

  • Use of nano nickel-based catalysts (90–99% Ni, 0.3–3.0% Co, 0.2–2.0% Al, Fe, Si) to enhance yield (98%) and purity (99%) under low-temperature (50°C) and low-pressure (5 kg/cm²) conditions .

Oxidation Reactions of this compound

Oxidation leads to the formation of this compound N-oxide and other derivatives, critical for pharmacological and analytical studies.

Oxidation by N-Bromo-p-Benzenesulphonamide (BAB)

• Reaction Conditions :

  • pH 1.2 acidic buffer.

  • 303K temperature.

• Kinetics :

  • First-order dependence on [BAB] and [this compound].

  • Inverse fractional order (-0.79) with respect to [H⁺] .

• Product :

  • This compound N-oxide (molecular ion peak at 293 amu via GC-MS) .

Permanganic Acid Oxidation

• Reaction Pathway :

  • Forms dibenzosuberone, 2-amino-3-methyl-1-butanol, and MnO₂ .

• Mechanism :

  • Initial carbocation formation followed by hydrolysis and oxidation steps .

Table: Oxidation Conditions and Products

Degradation Pathways

This compound undergoes metabolic and environmental degradation, influencing its therapeutic efficacy and environmental impact.

Metabolic Degradation

• Primary Pathway :

  • CYP2D6 hydroxylation of nortriptyline to (Z)- and (E)-10-hydroxynortriptyline (1:3 ratio) .

• Key Metabolites :

  • Nortriptyline (major), demethylnortriptyline .

• Pharmacogenetic Impact :

  • CYP2D6 poor metabolizers experience increased drug levels and side effects .

Environmental Degradation

• Hydrolysis :

  • Pseudo-first-order kinetics in basic conditions (pH 8) .

• Photodegradation :

  • Hydroxylation and alkene hydration under UV light or Co-TiO₂ catalysts .

  • Primary products: Hydroxylated derivatives (e.g., TP-ami-296) .

Table: Degradation Pathways

Kinetic Analysis

• Rate Law :

  • For BAB oxidation: $\text{Rate}=k[\text{this compound}][\text{BAB}][\text{H}^+]^{-0.79}$ .

• pH Sensitivity :

  • Protonation state of oxidants (e.g., BAB → PhSO₂NHBr) alters reactivity .

Product Identification

• Spectroscopic Data :

  • This compound N-oxide: $m/z=293$ (GC-MS) .

  • Hydroxylated derivatives: $m/z=278$ (LC-MS) .

Depression Treatment

Amitriptyline is primarily recognized for its efficacy in treating major depressive disorder. A meta-analysis of randomized controlled trials indicated that this compound has a slightly higher response rate compared to other antidepressants, including selective serotonin reuptake inhibitors (SSRIs) and other tricyclic antidepressants . The odds ratio favored this compound, suggesting its effectiveness in alleviating depressive symptoms.

Neuropathic Pain Management

This compound is frequently prescribed off-label for neuropathic pain conditions, such as diabetic neuropathy and postherpetic neuralgia. Research has shown that this compound can reduce pain intensity and improve quality of life in patients suffering from these chronic pain syndromes. A systematic review highlighted its role as a first-line treatment option for neuropathic pain .

Case Study: Diabetic Neuropathy

In a clinical study involving diabetic patients, those treated with this compound reported significant reductions in pain scores compared to placebo groups. The drug's mechanism appears to involve modulation of neurotransmitter levels and inhibition of pain pathways in the central nervous system .

Fibromyalgia

Fibromyalgia is another condition where this compound has shown promise. Studies indicate that low-dose this compound can help alleviate fibromyalgia symptoms, including widespread pain and sleep disturbances. A randomized controlled trial demonstrated that patients receiving this compound experienced significant improvements in their fibromyalgia impact scores compared to those receiving placebo .

Migraine Prophylaxis

This compound is also utilized for migraine prevention. Clinical evidence supports its efficacy in reducing the frequency and severity of migraine attacks. A study found that patients taking this compound had fewer migraine days per month compared to those on placebo, making it a valuable option for chronic migraine sufferers .

Irritable Bowel Syndrome (IBS)

Recent research has explored the use of this compound in managing irritable bowel syndrome symptoms. A large trial indicated that low-dose this compound significantly improved IBS symptom scores after six months of treatment, demonstrating its potential as an effective therapy for this condition .

Anxiety Disorders

This compound's anxiolytic properties have led to its use in treating anxiety disorders, particularly when these conditions co-occur with depression or chronic pain syndromes. While not first-line therapy for anxiety alone, it can be beneficial in complex cases where multiple symptoms overlap .

Chronic Pain Syndromes

Beyond neuropathic pain, this compound has been investigated for various chronic pain conditions, including complex regional pain syndrome (CRPS) and tension-type headaches. Its ability to modulate pain perception through central mechanisms makes it a relevant option in these contexts .

Summary Table of this compound Applications

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Tricyclic Antidepressants (TCAs)

Amitriptyline is often compared to other TCAs, such as imipramine and dothiepin :

Key Findings :

• This compound showed a 2.8% higher responder rate than SSRIs (NNTB 35) but with more side effects (NNTH 7.6) .
• Compared to dothiepin, this compound had a significantly lower proportion of responders (OR 0.81) .

Selective Serotonin Reuptake Inhibitors (SSRIs)

This compound vs. sertraline and fluoxetine :

Key Findings :

• In elderly patients, this compound and sertraline had comparable efficacy (69.4% vs. 62.5%), but this compound caused more somnolence and dry mouth .
• Fluoxetine’s Na⁺ channel blockade is slower and less potent than this compound’s, reducing cardiotoxicity risk .

Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs)

This compound vs. duloxetine in neuropathic pain:

Key Findings :

• Both drugs showed comparable efficacy in painful diabetic neuropathy (PDN), but duloxetine had better tolerability .

Other Antidepressants

• Trazodone : Unlike this compound, trazodone minimally blocks Na⁺ channels, reducing arrhythmia risk .
• Phenelzine (MAOI) : In a head-to-head trial, phenelzine and this compound had similar efficacy, but phenelzine required dietary restrictions .

Non-Pharmacological Comparators

• Spinal Manipulation : For chronic tension-type headaches, spinal manipulation provided sustained pain relief (32% intensity reduction) post-treatment, whereas this compound’s benefits diminished after discontinuation .
• Acupuncture : Equally effective as this compound in reducing headache frequency but with fewer adverse events (OR 0.19) .

Anesthetic Properties

This compound vs. lidocaine :

• Onset : this compound-induced numbness peaked at 40–45 minutes vs. lidocaine’s 15–20 minutes .
• Analgesia : Significantly lower VAS scores at 25–35 minutes for this compound (p < 0.001) .

Neuropathic Pain

• Efficacy : this compound’s NNT for 50% pain relief is 3.6, but evidence quality is low .
• Alternatives : Duloxetine and pregabalin are preferred due to better safety profiles .

Adverse Effect Profile

Amitriptyline is a tricyclic antidepressant (TCA) that has been widely used for the treatment of major depressive disorder and various pain conditions. Its biological activity extends beyond its antidepressant effects, involving complex interactions at the cellular and molecular levels. This article delves into the various aspects of this compound's biological activity, including its mechanisms of action, effects on cell viability, autophagy modulation, and additional pharmacological properties.

This compound primarily functions by inhibiting the reuptake of neurotransmitters, specifically serotonin and norepinephrine, thereby enhancing their availability in the synaptic cleft. This mechanism is crucial for its antidepressant effects and is mediated through the following pathways:

• Serotonin Transporter (SERT) Inhibition : this compound blocks SERT, leading to increased serotonin levels.
• Norepinephrine Transporter (NET) Inhibition : It also inhibits NET, enhancing norepinephrine availability.
• Receptor Binding : this compound exhibits strong binding affinities for various receptors, including:
  • Alpha-adrenergic receptors
  • Histamine (H1) receptors
  • Muscarinic (M1) receptors

These interactions contribute to its sedative effects and anticholinergic properties, which are more pronounced compared to other TCAs .

Effects on Cell Viability and Proliferation

Recent studies have shown that this compound affects cell viability in neuroblastoma cell lines (SH-SY5Y). Notably, it induces a concentration- and time-dependent reduction in cell viability. Key findings include:

• Cell Viability Reduction : At concentrations of 50 μM, cell viability decreased significantly over time; specifically, 81.03% at 24 hours, dropping to 43.60% by 72 hours .
• Clonogenic Capacity : this compound treatment reduced the clonogenic capacity of SH-SY5Y cells, indicating its potential cytotoxic effects .

Autophagy Modulation

This compound has been found to modulate autophagy in treated cells. However, its cytotoxic effects appear to be independent of autophagy modulation:

• Autophagy Inhibition Studies : When SH-SY5Y cultures were pre-treated with chloroquine (an autophagy inhibitor), this compound's effects on cell viability remained consistent, suggesting that its cytotoxicity does not rely on altering autophagic processes .
• Lysosomal Accumulation : this compound induced lysosomal accumulation without affecting lysosomal pH, further supporting its complex interaction with cellular homeostasis .

Additional Pharmacological Properties

Beyond its antidepressant activity, this compound exhibits several other biological activities:

• Antimicrobial Activity : Studies indicate that this compound possesses significant antibacterial properties against both Gram-positive and Gram-negative bacteria. In vivo experiments demonstrated a reduction in bacterial counts in mice treated with this compound after exposure to Salmonella typhimurium, highlighting its potential as an antimicrobial agent .

Case Studies and Clinical Implications

This compound's off-label use has been documented extensively. For instance:

• Chronic Pain Management : this compound is frequently prescribed for neuropathic pain management due to its analgesic properties.
• Sleep Disorders : Its sedative effects make it a common choice for treating insomnia associated with depression.

Basic Research Questions

Q. How can researchers design a robust randomized controlled trial (RCT) to assess amitriptyline’s efficacy in major depressive disorder (MDD)?

• Methodological Answer : Use the PICO framework (Population: MDD patients; Intervention: this compound; Comparison: Placebo; Outcome: Response rate) to structure the trial. Ensure double-blinding, adequate sample size (power analysis), and standardized diagnostic criteria (e.g., DSM-5). Monitor attrition bias by tracking withdrawal rates due to inefficacy or side effects, as seen in meta-analyses where this compound showed higher dropout rates due to adverse effects compared to placebo . Include validated depression scales (e.g., Hamilton Rating Scale for Depression [HRSD]) for outcome measurement .

Q. What statistical methods are recommended for analyzing contradictory efficacy data in this compound studies?

• Methodological Answer : Perform subgroup analyses (e.g., baseline severity, age) and meta-regression to explore heterogeneity. For instance, higher baseline depression severity correlates with greater this compound efficacy, while high placebo response rates diminish its perceived superiority . Use sensitivity analyses to assess robustness, such as excluding older trials with less rigorous randomization methods.

Q. How can researchers ensure adherence to ethical guidelines when designing this compound trials in vulnerable populations?

• Methodological Answer : Follow FINER criteria (Feasible, Interesting, Novel, Ethical, Relevant). Justify placebo use with equipoise and include rescue protocols for non-responders. Address anticholinergic side effects (e.g., dizziness, sedation) through proactive monitoring and dose titration . Obtain informed consent with explicit disclosure of withdrawal risks due to adverse events.

Advanced Research Questions

Q. What preclinical models best elucidate this compound’s dose-dependent neurotoxicity in peripheral nerves?

• Methodological Answer : Use rat sciatic nerve models to assess extraneural this compound application. Quantify neuropathologic injury via histopathology (e.g., axon degeneration, myelin disruption) and electrophysiological measurements (e.g., nerve conduction velocity). Dose-response studies (e.g., 6–8 nmol doses) reveal severe neurotoxicity, necessitating caution in clinical applications for neuropathic pain .

Q. How can network meta-analyses (NMAs) compare this compound’s efficacy against newer antidepressants?

• Methodological Answer : Conduct a Bayesian NMA integrating RCTs of this compound and FDA-approved drugs. Use standardized mean differences (SMDs) for continuous outcomes (e.g., HRSD scores) and odds ratios (ORs) for dichotomous outcomes (e.g., response rates). Adjust for confounding variables (e.g., study duration, dosing) and assess transitivity assumptions. Validate findings with node-splitting to detect inconsistency .

Q. What methodologies reconcile discrepancies in this compound’s clinical efficacy versus real-world prescription patterns?

• Methodological Answer : Perform retrospective cohort studies in LMICs using medicine use evaluations (MUEs). Analyze electronic health records for diagnosis concordance (e.g., adherence to Standard Treatment Guidelines) and dosing patterns. For example, a South African study found widespread off-label use and poor documentation, highlighting the need for clinician education and audit feedback .

Q. How do receptor-binding assays clarify this compound’s multimodal mechanisms in chronic pain management?

• Methodological Answer : Use radioligand binding assays to quantify affinity for serotonin (5-HT) and norepinephrine (NET) transporters. Pair with functional assays (e.g., cAMP inhibition) to assess downstream effects. Compare results with in vivo models (e.g., rodent neuropathic pain) to validate translational relevance. Note that sodium channel blockade contributes to local anesthetic effects but also neurotoxicity .

Q. Data and Reporting Standards

Q. What are best practices for reporting adverse events in this compound trials?

• Methodological Answer : Use CONSORT guidelines for adverse event reporting. Differentiate between common side effects (e.g., sedation, weight gain) and rare events (e.g., cardiac arrhythmias). Include severity grading (e.g., CTCAE criteria) and causality assessment (e.g., Naranjo Scale). Tabulate events by treatment arm with absolute risks and number needed to harm (NNH) .

Q. How should researchers address missing data in longitudinal studies of this compound’s long-term safety?

• Methodological Answer : Apply multiple imputation or mixed-effects models for repeated measures (MMRM) to handle missing data. Sensitivity analyses (e.g., worst-case scenario imputation) can assess robustness. For observational studies, use propensity score matching to reduce confounding by indication .

Q. Translational and Regulatory Challenges

Q. What strategies improve translational validity of preclinical this compound studies for neuropathic pain?

• Methodological Answer : Use species-specific pharmacokinetic modeling to align rodent doses with human equivalents. Validate behavioral endpoints (e.g., mechanical allodynia) with clinical pain scales. Collaborate with regulatory agencies early to align preclinical endpoints with clinical trial requirements .

Q. How can researchers navigate regulatory hurdles for repurposing this compound in new indications?

• Methodological Answer : Submit pre-IND meeting requests to agencies (e.g., FDA) to discuss nonclinical requirements. Leverage existing safety data from depression trials to support dose justification. For novel formulations (e.g., topical), conduct Phase I pharmacokinetic studies to establish bioavailability .