Irritable bowel syndrome: low dose antidepressant improves symptoms.

The studyFord AC, Wright-Hughes A, Alderson SL, et al. Amitriptyline at low-dose and titrated for irritable bowel syndrome as second-line treatment in primary care (ATLANTIS): a randomised, double-blind, placebo-controlled, phase 3 trial. Lancet 2023;402:1773-85.To read the full NIHR Alert, go to: https://evidence.nihr.ac.uk/alert/irritable-bowel-syndrome-low-dose-antidepressant-improves-symptoms/.

Amitriptyline at low-dose and titrated for irritable bowel syndrome as second-line treatment (The ATLANTIS trial): protocol for a randomised double-blind placebo-controlled trial in primary care.

BACKGROUND: Irritable bowel syndrome (IBS) is a common functional bowel disorder that has a considerable impact on patient quality of life and substantial societal and health care resource costs. Current treatments are often ineffective. Tricyclic antidepressants have shown promise in secondary care populations but their effectiveness in a primary care setting remains unclear. METHODS: ATLANTIS is a randomised, multi-centre, parallel-group, two-arm, double-blind, placebo-controlled trial of low-dose amitriptyline as a second-line treatment for IBS in primary care. Participants will be invited by letter, or recruited opportunistically, from general practices in three regions of England (West Yorkshire, Wessex, and West of England) and screened for eligibility. A total of 518 adult patients with IBS, who are symptomatic despite first-line therapies, will be randomised 1:1 to amitriptyline or identical placebo for 6 months. Treatment will commence at a dose of 10 mg (or one placebo tablet) daily at night, with dose titration up to a maximum of 30 mg at night, depending on side effects and response to treatment. Participant-reported assessments will be conducted at baseline and 3, 6, and 12 months post-randomisation. The primary objective is to determine the effectiveness of amitriptyline, compared with placebo, in improving participant-reported global symptoms of IBS at 6 months (using the IBS Severity Scoring System). Secondary outcomes include relief of IBS symptoms, effect on IBS-associated somatic symptoms (Patient Health Questionnaire-12), anxiety and depression (Hospital Anxiety and Depression Scale), ability to work and participate in other activities (Work and Social Adjustment Scale), acceptability and tolerability of treatment, self-reported health care use, health-related quality of life (EQ-5D-3L), and cost-effectiveness. A nested, qualitative study will explore patient and general practitioner experiences of treatments and trial participation, including acceptability, adherence, unanticipated effects, and implications for wider use of amitriptyline for IBS in primary care. DISCUSSION: Determining the clinical and cost-effectiveness of low-dose amitriptyline as a second-line treatment for IBS in primary care will provide robust evidence to inform management decisions. TRIAL REGISTRATION: ISRCTN ISRCTN48075063 . Registered on 7th June 2019.

Antioxidants Supplementation in Acute Amitriptyline Abuse for Pain.

The fundamental aim of this study is to establish the role of antioxidant supplementation in alleviating acute amitriptyline induced oxidative stress. The effect of supplementation was compared on treatment of acute amitriptyline intoxication cases for pain management, with alpha lipoic acid (ALA) alone or with vitamin C, with that of healthy individuals (group I), and those receiving only routine standard treatment (RST) as control (group II). A total of 132 human subjects divided into 5 groups were supplemented with either placebo, RST, RST with vitamin C, RST with ALA, or RST with vitamin C, and ALA. Results of this study revealed that the decrease in the level of oxidative stress and enzyme activity was observed among those supplemented with either alpha lipoic acid alone or along with vitamin C, with a slightly more decrease in the latter group. P value of < 0.001 was considered statistically significant. The percentage of benefit of treatment on supplementation with vitamin C and alpha lipoic acid showed a marked increase in group V cases after supplementation with both in combination. The results provided that the oxidative stress induced by acute amitriptyline poisoning is comparatively decreased by supplementation with antioxidants like alpha lipoic acid and vitamin C, than those only on routine standard treatment.

Treatment of patients with neuropathic pain and provision of drug information by clinical pharmacists

Abstract Patient's satisfaction with healthcare services has an influence on pain management, which can be improved by patient education. Therefore, this study was aimed at identifying primary care health service opportunities in the treatment of neuropathic pain and assessing patients' satisfaction with the provision of drug information by clinical pharmacists. This was a cross- sectional, prospective study conducted at a pain unit during March-May 2017. Patients aged >18 years; diagnosed with neuropathic pain; and who used amitriptyline, gabapentin, pregabalin, or duloxetine were included. They were verbally informed about drug treatment by a clinical pharmacist, and their satisfaction was evaluated after 1 month. In all, 90 patients were included. The median duration for which the patients experienced pain until hospital admission was 3.6 years; furthermore, this duration was longer among women (p < 0.05). However, the median time to seeking advice from doctors was 3 months. The patients (15.6%) were less likely to admit pain unit initially and 46.7% had visited different units before being admitted to a pain unit. More than 95% of the patients indicated that they had received information from a pharmacist at a clinic and were satisfied with the provision of information (median duration, 8.5 min). Thus, the involvement of pharmacists in multidisciplinary pain management may help improve health- related outcomes at hospitals and/or in community care settings

Synergistic interaction between amitriptyline and paracetamol in persistent and neuropathic pain models: An isobolografic analysis.

The current study was designed to evaluate the transient antinociceptive interaction between amitriptyline and paracetamol in the formalin test. In addition, considering other long-term neuroprotective mechanisms of these drugs, we hypothesized that this combination might exert some synergistic effects on neuropathic pain linked with its possible ability to prevent Wallerian degeneration (WD). The effects of individual and fixed-ratio of 1:1 combinations of orally administered amitriptyline and paracetamol were assayed in the two phases of the formalin test and in the chronic constriction injury (CCI) model in rats. Isobolographic analysis was employed to characterize the synergism produced by the combinations. Amitriptyline, paracetamol, and fixed-ratio amitriptyline-paracetamol combinations produced dose-dependent antinociceptive effects mainly on the inflammatory tonic phase. Repeated doses of individual drugs and their combination decreased CCI-induced mechanical allodynia in a dose-dependent manner. ED30 (formalin) and ED50 (CCI) values were estimated for the individual drugs, and isobolograms were constructed. Theoretical ED30/50 values for the combination estimated from the isobolograms were 16.5 ± 3.9 mg/kg and 26.0 ± 7.2 mg/kg for the single and repeated doses in persistent and neuropathic pain models, respectively. These values were significantly higher than the actually observed ED30/50 values, which were 0.39 ± 0.1 mg/kg and 8.2 ± 0.8 mg/kg in each model, respectively, indicating a synergistic interaction. Remarkably, CCI-induced sciatic nerve WD-related histopathological changes were prevented by this combination compared to either drug administered alone.

Gel tópico de amitriptilina al 2% y ketamina al 0, 5% para el tratamiento de la eritromelalgia: reporte de un caso con respuesta positiva al dolor / Combination gel of 2% amitriptyline and 0.5% ketamine to treat refractory erythromelalgia pain-a case report of pain control success

La eritromelalgia (EM) es una neuropatía inusual autosómica dominante caracterizada por la combinación de ardor intenso, extremidades eritematosas y cálidas. Con frecuencia el control del dolor crónico no tiene éxito, no habiéndose identificado aún una terapia efectiva. Los estudios recientes han identificado mejoras significativas en el manejo de dolor, utilizando una combinación de amitriptilina y ketamina en formulación tópica. Describimos un caso de respuesta positiva al dolor, con seguimiento de un año de un paciente con EM usando un gel tópico de combinación de amitriptilina al 2% y ketamina al 0,5%.(AU)

Erythromelalgia (EM) is a rare autosomal dominant neuropathy characterized by the combination of severe burning pain and erythematous warm extremities. Chronic pain control is most often unsuccessful and a completely effective therapy is yet to be identified. Recent studies have reported significant improvements in pain management using a combination of amitriptyline and ketamine in a topical formulation. We describe a 1-year follow-up pain control success case of a male patient with EM, proposed for topical use of a 2% Amitriptyline and 0.5% Ketamine gel.(AU)

Role of serum amitriptyline concentration and CYP2C19 polymorphism in predicting the response to low-dose amitriptyline in irritable bowel syndrome.

BACKGROUND: Low-dose amitriptyline (AMT) is an effective treatment for diarrhea-dominant irritable bowel syndrome (IBS-D). Its efficacy depends upon its serum concentration and the patient's CYP2C19 genotype. AIMS: To identify the association between serum AMT and nortriptyline (NT) concentration and CYP2C19 polymorphism and the clinical response in IBS-D patients. METHODS: Ninety IBS-D patients were treated of AMT for 6 weeks. Efficacy was evaluated by the results of the Adequate Relief question each week and an IBS severity scoring system (IBS-SSS) at 0, 3, and 6 weeks. CYP2C19 genotyping was performed by direct sequencing. AMT and NT steady-state serum concentrations were detected by high-performance liquid chromatography. RESULTS: The CYP2C19 polymorphism exhibited a significant influence on the NT serum concentration but did not predict the clinical efficacy of AMT for treating IBS-D. The NT steady-state and dose-corrected serum concentrations were significantly correlated with an improvement in the IBS-SSS score after 6 weeks, whereas the AMT serum concentration was not correlated with clinical improvement. The cut-off NT steady-state serum concentration of 2.91 ng/ml may help distinguish responders from non-responders. CONCLUSIONS: NT serum concentration but not CYP2C19 polymorphism may be correlated with the clinical efficacy of AMT for treating IBS-D, and such a response may occur at the upper NT threshold of 2.91 ng/ml.

Amitriptyline functionally antagonizes cardiac H2 histamine receptors in transgenic mice and human atria.

We have previously shown that histamine (2-(1H-imidazol-4-yl)ethanamine) exerted concentration-dependent positive inotropic effects (PIE) or positive chronotropic effects (PCE) on isolated left and right atria, respectively, of transgenic (H2R-TG) mice that overexpress the human H2 histamine receptor (H2R) in the heart; however, the effects were not seen in their wild-type (WT) littermates. Amitriptyline, which is still a highly prescribed antidepressant drug, was reported to act as antagonist on H2Rs. Here, we wanted to determine whether the histamine effects in H2R-TG were antagonized by amitriptyline. Contractile studies were performed on isolated left and right atrial preparations, isolated perfused hearts from H2R-TG and WT mice and human atrial preparations. Amitriptyline shifted the concentration-dependent PIE of histamine (1 nM-10 µM) to higher concentrations (rightward shift) in left atrial preparations from H2R-TG. Similarly, in isolated perfused hearts from H2R-TG and WT mice, histamine increased the contractile parameters and the phosphorylation state of phospholamban (PLB) at serine 16 in the H2R-TG mice, but not in the WT mice. However, the increases in contractility and PLB phosphorylation were attenuated by the addition of amitriptyline in perfused hearts from H2R-TG. In isolated electrically stimulated human atria, the PIE of histamine that was applied in increasing concentrations from 1 nM to 10 µM was reduced by 10-µM amitriptyline. In summary, we present functional evidence that amitriptyline also acts as an antagonist of contractility at H2Rs in H2R-TG mouse hearts and in the human heart which might in part explain the side effects of amitriptyline.

Effects of Low-Dose Amitriptyline on Epigastric Pain Syndrome in Functional Dyspepsia Patients.

AIM: To observe the therapeutic effect of low-dose amitriptyline (AMT) on epigastric pain syndrome (EPS) in patients with functional dyspepsia. METHODS: Sixty patients with EPS were randomly divided into the following two groups for a four-week clinical trial: routine treatment with pantoprazole (RT group) and the AMT group. The RT group was treated with 40 mg of pantoprazole once daily. The AMT group received 25 mg of AMT once daily before bedtime. The Nepean Dyspepsia Index (NDI) checklist, Hamilton Rating Scale of Anxiety/Depression (HAMA/HAMD), and Pittsburgh Sleep Quality Index (PSQI) were employed to evaluate dyspepsia symptoms, psychological distress, and sleep, respectively. RESULTS: All items were similar between the two groups before treatment (0 week). After 4 weeks of treatment, the NDI-symptom checklist score as well as the severity and bothersomeness of EPS in the AMT group was significantly decreased compared with those in the RT group (p < 0.05). However, no differences were found in the frequency of NDI checklist, psychological status (HAMD/HAMA scores) of EPS, or sleep quality (PSQI score) between the two groups after treatment. In addition, the time to fall asleep was shorter in the AMT group compared with the RT group after 4 weeks of treatment (p < 0.05). CONCLUSION: Low-dose AMT effectively improved the dyspepsia symptoms and the time to fall asleep in the EPS patients, compared with pantoprazole, although it did not reduce the psychological distress. Therefore, AMT could be considered as a good candidate for EPS treatment in the clinic.

Anti-inflammatory effect of amitriptyline in a rat model of acetic acid-induced colitis: the involvement of the TLR4/NF-kB signaling pathway.

Inflammatory bowel disease (IBD) consists of ulcerative colitis and Crohn's disease, which affects gastrointestinal tract. The immune-mediated inflammation is mostly considered as the pathogenesis of IBD. It has been demonstrated that amitriptyline exerts anti-inflammatory influence; therefore, the aim of the current experiment is to evaluate the anti-inflammatory impact of amitriptyline on intestinal disorders following acetic acid-induced colitis in rats. Thirty male Wistar rats were randomly divided into five groups, including sham, control, dexamethasone (2 mg/kg), and amitriptyline (10 and 20 mg/kg). Intrarectal administration of acetic acid was applied to colitis induction in all study groups except for sham group. Animals were treated by oral administration of dexamethasone or amitriptyline. While macroscopic and microscopic lesions appeared after colitis induction treatment with dexamethasone and amitriptyline 10 and 20 mg/kg significantly improved lesions. Moreover, Toll-like receptor 4 (TLR4) and nuclear factor binding kappa light-chain (NF-ĸB expression), tumor necrosis factor-alpha (TNF-α) level, and myeloperoxidase (MPO) activity were increased after colitis induction, whereas treatment with dexamethasone (2 mg/kg) or amitriptyline (10 and 20 mg/kg) caused a noticeable decrease in the TLR4 and pNF-ĸB expression, TNF-α level, and MPO activity. In conclusion, amitriptyline plays an anti-inflammatory role through the suppression of TLR4/pNF-ĸB signaling pathway in the rat model of acute colitis.

Trk agonist drugs rescue noise-induced hidden hearing loss.

TrkB agonist drugs are shown here to have a significant effect on the regeneration of afferent cochlear synapses after noise-induced synaptopathy. The effects were consistent with regeneration of cochlear synapses that we observed in vitro after synaptic loss due to kainic acid-induced glutamate toxicity and were elicited by administration of TrkB agonists, amitriptyline, and 7,8-dihydroxyflavone, directly into the cochlea via the posterior semicircular canal 48 hours after exposure to noise. Synaptic counts at the inner hair cell and wave 1 amplitudes in the auditory brainstem response (ABR) were partially restored 2 weeks after drug treatment. Effects of amitriptyline on wave 1 amplitude and afferent auditory synapse numbers in noise-exposed ears after systemic (as opposed to local) delivery were profound and long-lasting; synapses in the treated animals remained intact 1 year after the treatment. However, the effect of systemically delivered amitriptyline on synaptic rescue was dependent on dose and the time window of administration: it was only effective when given before noise exposure at the highest injected dose. The long-lasting effect and the efficacy of postexposure treatment indicate a potential broad application for the treatment of synaptopathy, which often goes undetected until well after the original damaging exposures.

Analgesic Effects of Topical Amitriptyline in Patients With Chemotherapy-Induced Peripheral Neuropathy: Mechanistic Insights From Studies in Mice.

Oral amitriptyline hydrochloride (amitriptyline) is ineffective against some forms of chronic pain and is often associated with dose-limiting adverse events. We evaluated the potential effectiveness of high-dose topical amitriptyline in a preliminary case series of chemotherapy-induced peripheral neuropathy patients and investigated whether local or systemic adverse events associated with the use of amitriptyline were present in these patients. We also investigated the mechanism of action of topically administered amitriptyline in mice. Our case series suggested that topical 10% amitriptyline treatment was associated with pain relief in chemotherapy-induced peripheral neuropathy patients, without the side effects associated with systemic absorption. Topical amitriptyline significantly increased mechanical withdrawal thresholds when applied to the hind paw of mice, and inhibited the firing responses of C-, Aß- and Aδ-type peripheral nerve fibers in ex vivo skin-saphenous nerve preparations. Whole-cell patch-clamp recordings on cultured sensory neurons revealed that amitriptyline was a potent inhibitor of the main voltage-gated sodium channels (Nav1.7, Nav1.8, and Nav1.9) found in nociceptors. Calcium imaging showed that amitriptyline activated the transient receptor potential cation channel, TRPA1. Our case series indicated that high-dose 10% topical amitriptyline could alleviate neuropathic pain without adverse local or systemic effects. This analgesic action appeared to be mediated through local inhibition of voltage-gated sodium channels. PERSPECTIVE: Our preliminary case series suggested that topical amitriptyline could provide effective pain relief for chemotherapy-induced peripheral neuropathy patients without any systemic or local adverse events. Investigation of the mechanism of this analgesic action in mice revealed that this activity was mediated through local inhibition of nociceptor Nav channels.

Amitriptyline Protects Against Lidocaine-induced Neurotoxicity in SH-SY5Y Cells via Inhibition of BDNF-mediated Autophagy.

Amitriptyline (AMI) is a traditional tricyclic antidepressant that has been proven to exhibit neuroprotective effects in various neurological disorders. However, the underlying mechanism by which AMI attenuates lidocaine-induced neurotoxicity remains poorly understood. Brain-derived neurotrophic factor (BDNF) is an essential neurotrophin to neuronal development and survival in the brain, and recent studies have suggested that BDNF plays an important role in mediating lidocaine-induced neurotoxicity. The present study was performed to evaluate the protective effect of AMI against the neurotoxicity induced by lidocaine and to explore the role of BDNF-dependent autophagy in this process. The data showed that AMI pretreatment alleviated lidocaine-induced neurotoxicity, as evidenced by the restoration of cell viability, normalization of cell morphology, and reduction in the cell apoptosis index. In addition, autophagy inhibitor 3-methyladenine (3-MA) had a protective effect similar to that of AMI, but autophagy activator rapamycin eliminated the protective effect of AMI by suppressing mTOR activation. Moreover, at the molecular level, we found that AMI-mediated autophagy was involved in the expression of BDNF. The overexpression of BDNF or application of exogenous recombinant BDNF significantly suppressed autophagy and protected SH-SY5Y cells from apoptosis induced by Lido, whereas the neuroprotection of AMI was abolished by either knockdown of BDNF or use of a tropomyosin-related kinase B (TrkB) inhibitor ANA-12 in SH-SY5Y cells. Overall, our findings demonstrated that the protective effect of AMI against lidocaine-induced neurotoxicity correlated with inhibition of autophagy activity through upregulation of BDNF expression.

Observational study on the effects of a topical formulation in patients with premature ejaculation.

Premature ejaculation (PE) has been defined as the inability to control or delay ejaculation, resulting in dissatisfaction or distress of the patient. Although PE is the most frequent sexual dysfunction, it is still underdiagnosed. An accurate clinical history is the best diagnostic approach that, in the majority of cases, is enough to differentiate between primary and acquired PE. Nowadays, treatment is not curative but is effective in increasing the intravaginal ejaculatory latency time (IELT), improving the sexual satisfaction of the couple [...].

Cognitive impairment in a classical rat model of chronic migraine may be due to alterations in hippocampal synaptic plasticity and N-methyl-D-aspartate receptor subunits.

Although migraine is a major global public health problem, its impact on cognitive abilities remains controversial. Thus, the present study investigated the effects of repeated administration of inflammatory soup to the dura of rats, over three weeks, on spatial cognition, hippocampal synaptic plasticity, and the expression of N-methyl-D-aspartate receptor subunits. Additionally, low doses of amitriptyline (5 mg/kg) were applied to assess its therapeutic effects. The inflammatory soup group exhibited significant reductions in the cutaneous stimulation threshold, presence of mild cognitive impairment, and decreased long-term potentiation in right hippocampus. However, amitriptyline improved pain behaviors, enhanced cognitive function, and increased synaptic plasticity in the inflammatory soup rats. On the other hand, the administration of amitriptyline to normal rats negatively influenced synaptic plasticity and reduced the expression of N-methyl-D-aspartate receptor subunits. The present results indicate that inflammatory soup-induced dural nociception led to impairments in spatial cognition that could be attributed to reductions in hippocampal long-term potentiation and the decreased expression of N-methyl-D-aspartate receptor subunits.

Bioequivalence Study of Amitriptyline Hydrochloride Tablets in Healthy Chinese Volunteers Under Fasting and Fed Conditions.

PURPOSE: This study compares the pharmacokinetic and safety profiles between a new generic and a branded reference formulation of amitriptyline hydrochloride tablets, and assesses the bioequivalence of the two products in healthy Chinese volunteers to obtain sufficient evidence for the marketing approval of the generic drug. MATERIALS AND METHODS: A randomized, open-label, two-period crossover study (clinicaltrials.gov, NCT03646526) was conducted under both fasting and fed conditions in healthy Chinese volunteers (24 subjects/condition). Eligible subjects randomly received a single 25 mg dose of either the test or the reference formulation, followed by a 3-week washout period. Blood samples were collected until 144 h following administration. The pharmacokinetic parameters were acquired based on the concentration-time profiles, including the areas under the plasma concentration-time curve (AUC0-t, AUC0-∞), the peak plasma concentration (Cmax), the time to achieve Cmax (Tmax), and the elimination half-life (t1/2). The geometric mean ratios (GMRs) and the corresponding 90% confidence intervals (CIs) of amitriptyline were acquired for bioequivalence analysis, and values of these parameters for nortriptyline were used for comparison of therapeutic outcomes. Safety assessments included laboratory tests, physical examination, vital signs, and incidence of adverse events (AEs). RESULTS: The values of t1/2 and Tmax for amitriptyline were not significantly different between the test and reference products under both fasting and fed conditions (P > 0.05). The GMRs of Cmax, AUC0-t, and AUC0-∞ between the two products, and corresponding 90% CIs, were all within the range of 80% to 125% under both fasting and fed conditions. The test and reference products were well tolerated and did not elicit serious adverse events. CONCLUSION: This study demonstrated that the generic and reference products were well tolerated by the subjects and bioequivalent, according to the rate and extent of the drug absorption.

Amitriptyline prescribing in public sector healthcare facilities in the Western Cape, South Africa.

BACKGROUND: Inappropriate medication use is a major patient safety concern, especially for the elderly population. Amitriptyline is widely used in primary care in South Africa and a cross-sectional study found that amitriptyline was prescribed potentially inappropriately in 6.5% of elderly patients. An analysis of prescriptions from the Chronic Dispensing Unit in the Western Cape revealed that amitriptyline was one of the most common medicines prescribed without a suitable diagnosis listed on the prescription. OBJECTIVE: The main objective of the medicine use evaluation (MUE) was to determine whether amitriptyline was prescribed in accordance with recommendations from standard treatment guidelines (STG) and essential medicines lists (EML) endorsed by the National Department of Health, South Africa. METHODS: A retrospective, cross-sectional, multicentre review of patients' clinical notes was conducted. The study population was selected by systematic random sampling from adult outpatients who were prescribed amitriptyline for longer than three months. Criteria for evaluation included amitriptyline indication and total daily dose prescribed. RESULTS: Of the sample of 2237 patient medical records reviewed, 1732 (77.4%) included amitriptyline prescriptions that were according to the approved STG indications. For the approved STG indications, amitriptyline was prescribed mainly for osteoarthritis (25.8%), neuropathies (18.5%) and chronic non-cancer pain (17.9%). Major depressive disorders constituted only 8.6% of the patient records reviewed; however, doses were atypically low. The main inappropriate indication for amitriptyline was sleep disorders (16%). CONCLUSION: This MUE has highlighted the need to improve the use of amitriptyline in specific patient populations, e.g. the elderly and patients with sleeping disorders.

Pharmacokinetic study of oral amitriptyline in horses.

The purpose of this study was to evaluate the pharmacokinetics of oral amitriptyline in horses. Oral amitriptyline (1 mg/kg) was administered to six horses. Blood samples were collected from jugular and lateral thoracic vein at predetermined times from 0 to 24 hr after administration. Plasma concentrations were determined by high-performance liquid chromatography and analyzed using noncompartmental methods. Pharmacodynamic parameters including heart rate, respiration rate, and intestinal motility were evaluated, and electrocardiographic examinations were performed in all subjects. The mean maximum plasma concentration (Cmax ) of amitriptyline was 30.7 ng/ml, time to maximum plasma concentration (Tmax ) 1-2 hr, elimination half-life (t1/2 ) 17.2 hr, area under plasma concentration-time curve (AUC) 487.4 ng ml-1  hr-1 , apparent clearance (Cl/F) 2.6 L hr-1  kg-1 , and apparent volume of distribution (Vd/F) 60.1 L/kg. Jugular vein sampling overestimated the amount of amitriptyline absorbed and should not be used to study uptake following oral administration. Heart rate and intestinal motility showed significant variation (p < .05). Electrocardiography did not provide conclusive results. Further studies are required to discern if multiple dose treatment would take the drug to steady state as expected, consequently increasing plasma concentrations.