Precision dosing for patients on tricyclic antidepressants

OBJECTIVE

We aim to develop a personalized dosing tool for tricyclic antidepressants (TCAs) that integrates CYP2D6 and CYP2C19 gene variants and their effects while also considering the polypharmacy effect.

METHODS

The study first adopted a scoring system that assigns weights to each genetic variant. A formula was then developed to compute the effect of both genes' variants on drug dosing. The output of the formula was assessed by a comparison with the clinical pharmacogenetics implementation consortium recommendation. The study also accounts for the effect of the co-administration of inhibitors and inducers on drug metabolism. Accordingly, a user-friendly tool, Clinical Dosing Tool ver.2, was created to assist clinicians in dosing patients on TCAs.

RESULTS

The study provides a comprehensive list of all alleles with corresponding activity values and phenotypes for both enzymes. The tool calculated an updated area under the curve ratio that utilizes the effects of both enzymes' variants for dose adjustment. The tool provided a more accurate individualized dosing that also integrates the polypharmacy effect.

CONCLUSION

To the best of our knowledge, the literature misses such a tool that provides a numerical adjusted dose based on continuous numerical activity scores for the considered patients' alleles and phenoconversion.

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/.

Differences in Cerebral Distribution between Imipramine and Paroxetine via Membrane Transporters at the Rat Blood-Brain Barrier

PURPOSE

The present study aimed to elucidate the transport properties of imipramine and paroxetine, which are the antidepressants, across the blood-brain barrier (BBB) in rats.

METHODS

In vivo influx and efflux transport of imipramine and paroxetine across the BBB were tested using integration plot analysis and a combination of brain efflux index and brain slice uptake studies, respectively. Conditionally immortalized rat brain capillary endothelial cells, TR-BBB13 cells, were utilized to characterize imipramine and paroxetine transport at the BBB in vitro.

RESULTS

The in vivo influx clearance of [3H]imipramine and [3H]paroxetine in rats was determined to be 0.322 mL/(min·g brain) and 0.313 mL/(min·g brain), respectively. The efflux clearance of [3H]imipramine and [3H]paroxetine was 0.380 mL/(min·g brain) and 0.126 mL/(min·g brain), respectively. These results suggest that the net flux of paroxetine, but not imipramine, at the BBB in vivo was dominated by transport to the brain from the circulating blood. The uptake of imipramine and paroxetine by TR-BBB13 cells exhibited time- and temperature-dependence and one-saturable kinetics with a Km of 37.6 μM and 89.2 μM, respectively. In vitro uptake analyses of extracellular ion dependency and the effect of substrates/inhibitors for organic cation transporters and transport systems revealed minor contributions to known transporters and transport systems and the difference in transport properties in the BBB between imipramine and paroxetine.

CONCLUSIONS

Our study showed the comprehensive outcomes of imipramine and paroxetine transport at the BBB, implying that molecular mechanism(s) distinct from previously reported transporters and transport systems are involved in the transport.

Antidepressant use and colorectal cancer morbidity and mortality: A dose-response meta analysis

The risk of colorectal cancer associated to antidepressant use remains unclear. The purpose of this meta-analysis was to investigate the risk of colorectal cancer associated to antidepressant use.Medline, Embase, Web of Science, and Cochrane Database were accessed from the dates of their establishment to October 2018, to collect study of antidepressant use and colorectal cancer morbidity and mortality. Then a meta-analysis was conducted using Stata 12.0 software.A total of 11 publications involving 109,506 participants were included. The meta-analysis showed that antidepressant use was not associated with colorectal cancer morbidity (relevant risk (RR): 0.97; 95% confidence interval (CI): 0.94-1.01) and mortality (RR: 1.08; 95% CI: 0.99-1.17). Subgroup analysis showed selective serotonin reuptake inhibitor (RR: 0.99; 95% CI: 0.96-1.03) or serotonin norepinephrine reuptake inhibitor (RR: 1.04; 95% CI: 0.86-1.26) were not associated with colorectal cancer risk; however, TCA was associated with colorectal cancer risk decrement (RR: 0.92; 95% CI: 0.87-0.98). Furthermore, the results also showed that antidepressant use was not associated with colorectal cancer risk in Europe and North America (RR: 0.97; 95% CI: 0.92-1.02) and Asia (RR: 1.00; 95% CI: 0.95-1.26). Additionally, a dose-response showed per 1 year of duration of antidepressant use incremental increase was not associated with colorectal cancer risk (RR: 0.96; 95% CI: 0.87-1.09).Evidence suggests that antidepressant use was not associated with colorectal cancer morbidity and mortality. The cumulative duration of antidepressant use did not utilized played critical roles.

Preliminary Biochemical Description of Brain Oxidative Stress Status in Irritable Bowel Syndrome Contention-Stress Rat Model

Background and objectives: Oxidative stress and inflammation have been implicated in the etiology of irritable bowel syndrome (IBS), a common gastrointestinal functional disease. This study aimed to further characterize the contention-stress rat model by exploring a possible correlation between oxidative stress markers measured in brain tissues with behavioral components of the aforementioned model. Thus, it is hereby proposed a possible IBS animal model relevant to pharmacological and complementary medicine studies. Materials and Methods: Wild-type male Wistar rats (n = 5/group) were chronically exposed to 6-hour/day contention, consisting of isolating the animals in small, vital space-granting plastic devices, for seven consecutive days. Following contention exposure, temporal lobes were extracted and subjected to biochemical analyses to assess oxidative stress-status parameters. Results: Our results show increased brain oxidative stress in contention-stress rat model: decreased superoxide dismutase and glutathione peroxidase activities and increased malondialdehyde production in the IBS group, as compared to the control group. Furthermore, the biochemical ratios which are used to evaluate the effectiveness of an antioxidant system on oxidative stress could be described in this model. Conclusions: The correlations between the behavioral patterns and biochemical oxidative stress features could suggest that this may be a complex model, which can successfully mimic IBS symptomatology further providing evidence of a strong connection between the digestive system, enteric nervous system, and the central nervous system.

Desipramine restores the alterations in circadian entrainment induced by prenatal exposure to glucocorticoids

Alterations in circadian rhythms are closely linked to depression, and we have shown earlier that progressive alterations in circadian entrainment precede the onset of depression in mice exposed in utero to excess glucocorticoids. The aim of this study was to investigate whether treatment with the noradrenaline reuptake inhibitor desipramine (DMI) could restore the alterations in circadian entrainment and prevent the onset of depression-like behavior. C57Bl/6 mice were exposed to dexamethasone (DEX-synthetic glucocorticoid analog, 0.05 mg/kg/day) between gestational day 14 and delivery. Male offspring aged 6 months (mo) were treated with DMI (10 mg/kg/day in drinking water) for at least 21 days before behavioral testing. We recorded spontaneous activity using the TraffiCage™ system and found that DEX mice re-entrained faster than controls after an abrupt advance in light-dark cycle by 6 h, while DMI treatment significantly delayed re-entrainment. Next we assessed the synchronization of peripheral oscillators with the central clock (located in the suprachiasmatic nucleus-SCN), as well as the mechanisms required for entrainment. We found that photic entrainment of the SCN was apparently preserved in DEX mice, but the expression of clock genes in the hippocampus was not synchronized with the light-dark cycle. This was associated with downregulated mRNA expression for arginine vasopressin (AVP; the main molecular output entraining peripheral clocks) in the SCN, and for glucocorticoid receptor (GR; required for the negative feedback loop regulating glucocorticoid secretion) in the hippocampus. DMI treatment restored the mRNA expression of AVP in the SCN and enhanced GR-mediated signaling by upregulating GR expression and nuclear translocation in the hippocampus. Furthermore, DMI treatment at 6 mo prevented the onset of depression-like behavior and the associated alterations in neurogenesis in 12-mo-old DEX mice. Taken together, our data indicate that DMI treatment enhances GR-mediated signaling and restores the synchronization of peripheral clocks with the SCN and support the hypothesis that altered circadian entrainment is a modifiable risk factor for depression.

A single injection of imipramine affected proliferation in the hippocampus of adult Swiss mice depending on the route of administration, doses, survival time and lodging conditions

Swiss mice may be valuable for the screening of antidepressants in preclinical trials. Acute treatment with antidepressants may affect the behaviour of Swiss mice, but the effects on their hippocampal neurogenesis remain unknown. The present work aims to assess the influence of acute treatment with antidepressants on cell proliferation in the dentate gyrus of the hippocampus of adult Swiss mice. Cell proliferation was estimated by ex vivo counting of Ki-67 immunoreactive nuclei (Ki-67-ir) in the dentate gyrus of Swiss mice housed in standard or enriched environments, at survival-times 2 or 24 h after imipramine injection Independent of the experimental group, intraperitoneal imipramine (0 or 30 mg/kg) failed to change the number of Ki-67-ir in the hippocampus of mice. Through intracerebroventricular route, imipramine reduced the number of Ki-67-ir in the hippocampus of Swiss mice at the dose of 0.06 nmol and increased it at the dose 0.2 nmol. At the dose 0.2 nmol, not 0.06 nmol, imipramine increased the immunoreactivity to doublecortin (a marker for immature neurons) in the hippocampus of mice. The effects of intracerebroventricular injection of imipramine on neurogenesis markers were seen 24 h after the injection in mice housed in standard conditions. The effects of intracerebroventricular injection of imipramine on neurogenesis markers were absent in mice housed in enrichment or 2 h after the injection. These data suggest that acute treatment with imipramine may affect proliferation in the hippocampus of adult Swiss mice depending on the route of administration, doses, survival time and lodging conditions.

Strategies to Treat Chronic Pain and Strengthen Impaired Descending Noradrenergic Inhibitory System

Gabapentinoids (gabapentin and pregabalin) and antidepressants (tricyclic antidepressants and serotonin noradrenaline reuptake inhibitors) are often used to treat chronic pain. The descending noradrenergic inhibitory system from the locus coeruleus (LC) to the dorsal horn of the spinal cord plays an important role in the analgesic mechanisms of these drugs. Gabapentinoids activate the LC by inhibiting the release of γ-aminobutyric acid (GABA) and inducing the release of glutamate, thereby increasing noradrenaline levels in the spinal cord. Antidepressants increase noradrenaline levels in the spinal cord by inhibiting reuptake, and accumulating noradrenaline inhibits chronic pain through α₂-adrenergic receptors in the spinal cord. Recent animal studies, however, revealed that the function of the descending noradrenergic inhibitory system is impaired in chronic pain states. Other recent studies found that histone deacetylase inhibitors and antidepressants restore the impaired noradrenergic descending inhibitory system acting on noradrenergic neurons in the LC.

Iatrogénie médicamenteuse chez la personne âgée: à propos de deux cas d’insuffisance rénale favorisée par les tricycliques

L'hyperplasie prostatique est une affection courante chez l'homme à partir de la cinquantaine dont l'incidence augmente avec l'âge. Elle est préoccupante lorsqu'elle est symptomatique. Les médicaments ayant des effets néfastes sur le fonctionnement du bas appareil urinaire, peuvent favoriser l'apparition des symptômes. Parmi ceux-ci, les médicaments à effets primaires ou secondaires anticholinergiques dont les tricycliques sont souvent en cause. Ils sont contre-indiqués en cas de pathologie obstructive sous vésicale parce que pouvant être responsable de l'apparition ou l'aggravation des symptômes urinaires et des complications qui en découlent. La plus grave est l'insuffisance rénale avec ses conséquences sanitaires et économiques chez les sujets âgés souvent polypathologiques. Nous rapportons deux cas de iatrogénie des tricycliques sur l'appareil urinaire chez des patients âgés de 80 et 92ans porteurs d'hyperplasie prostatique. L'imagerie et le Bladder scan ont permis de poser le diagnostic étiologique du fait de la pauvreté sémiologique permettant une prise en charge adéquate. Ces observations justifient la réalisation systématique du toucher rectal, du Bladder scan voire d'une échographie chez tout sujet âgé présentant une insuffisance rénale aiguë ou une aggravation d'une insuffisance chronique du fait de la fréquence des pathologies prostatiques et de la polymédication à cet âge.

Pharmacokinetic study of tianeptine and its active metabolite MC5 in rats following different routes of administration using a novel liquid chromatography tandem mass spectrometry analytical method

Tianeptine is an atypical antidepressant with a unique mechanism of action and recently it has been also reported that its major metabolite, compound MC5, possesses pharmacological activity similar to that of the parent drug. The current study aims to investigate the pharmacokinetics (PK) of both tianeptine and MC5 after intravenous or intraperitoneal administration of the parent drug as well as the metabolic ratio of MC5 in rats. To achieve these goals an LC-MS/MS method using the small sample volume for the quantitation of tianeptine and its active metabolite MC5 in rat plasma and liver perfusate has been developed and validated. Following an intravenous administration of tianeptine pharmacokinetic parameters were calculated by non-compartmental analysis. The average tianeptine volume of distribution at steady state was 2.03 L/kg and the systemic clearance equaled 1.84 L/h/kg. The mean elimination half-lives of tianeptine and MC5 metabolite were 1.16 and 7.53 h, respectively. The hepatic clearance of tianeptine determined in the isolated rat liver perfusion studies was similar to the perfusate flow rate despite the low metabolic ratio of MC5. Mass spectrometric analysis of rat bile indicated that tianeptine and MC5 metabolite are eliminated with bile as glucuronide and glutamine conjugates. Bioavailability of tianeptine after its intraperitoneal administration was 69%. The PK model with a metabolite compartment developed in this study for both tianeptine and MC5 metabolite after two routes of administration may facilitate tianeptine dosage selection for the prospective pharmacological experiments.

Oral paracetamol (acetaminophen) for cancer pain

BACKGROUND

Pain is a common symptom with cancer, and 30% to 50% of all people with cancer will experience moderate to severe pain that can have a major negative impact on their quality of life. Non-opioid drugs are commonly used to treat mild to moderate cancer pain, and are recommended for this purpose in the WHO cancer pain treatment ladder, either alone or in combination with opioids.A previous Cochrane review that examined the evidence for nonsteroidal anti-inflammatory drugs (NSAIDs) or paracetamol, alone or combined with opioids, for cancer pain was withdrawn in 2015 because it was out of date; the date of the last search was 2005. This review, and another on NSAIDs, updates the evidence.

OBJECTIVES

To assess the efficacy of oral paracetamol (acetaminophen) for cancer pain in adults and children, and the adverse events reported during its use in clinical trials.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, and Embase from inception to March 2017, together with reference lists of retrieved papers and reviews, and two online study registries.

SELECTION CRITERIA

We included randomised, double-blind, studies of five days' duration or longer, comparing paracetamol alone with placebo, or paracetamol in combination with an opioid compared with the same dose of the opioid alone, for cancer pain of any intensity. Single-blind and open studies were also eligible for inclusion. The minimum study size was 25 participants per treatment arm at the initial randomisation.

DATA COLLECTION AND ANALYSIS

Two review authors independently searched for studies, extracted efficacy and adverse event data, and examined issues of study quality and potential bias. We did not carry out any pooled analyses. We assessed the quality of the evidence using GRADE and created a 'Summary of findings' table.

MAIN RESULTS

Three studies in adults satisfied the inclusion criteria, lasting up to one week; 122 participants were randomised initially, and 95 completed treatment. We found no studies in children. One study was parallel-group, and two had a cross-over design. All used paracetamol as an add-on to established treatment with strong opioids (median daily morphine equivalent doses of 60 mg, 70 mg, and 225 mg, with some participants taking several hundred mg of oral morphine equivalents daily). Other non-paracetamol medication included non-steroidal anti-inflammatory drugs (NSAIDs), tricyclic antidepressants, or neuroleptics. All studies were at high risk of bias for incomplete outcome data and small size; none was unequivocally at low risk of bias.None of the studies reported any of our primary outcomes: participants with pain reduction of at least 50%, and at least 30%, from baseline; participants with pain no worse than mild at the end of the treatment period; participants with Patient Global Impression of Change (PGIC) of much improved or very much improved (or equivalent wording). What pain reports there were indicated no difference between paracetamol and placebo when added to another treatment. There was no convincing evidence of paracetamol being different from placebo with regards to quality of life, use of rescue medication, or participant satisfaction or preference. Measures of harm (serious adverse events, other adverse events, and withdrawal due to lack of efficacy) were inconsistently reported and provided no clear evidence of difference.Our GRADE assessment of evidence quality was very low for all outcomes, because studies were at high risk of bias from several sources.

AUTHORS' CONCLUSIONS

There is no high-quality evidence to support or refute the use of paracetamol alone or in combination with opioids for the first two steps of the three-step WHO cancer pain ladder. It is not clear whether any additional analgesic benefit of paracetamol could be detected in the available studies, in view of the doses of opioids used.

[Aripiprazole-Induced Hyperhidrosis: Two Case Reports]

Many drugs including anti-depressants and anti-psychotics are known to cause excessive sweating (hyperhidrosis). Hyperhidrosis may be caused by drugs acting at the hypothalamus, spinal thermoregulatory centres, and sympathetic ganglia or at the eccrine-neuroeffector junction. Hyperhidrosis can be distressing and embarrassing symptom, which if not addressed properly, may lead to non-concordance to medication. Two female patients are reported here who developed hyperhidrosis with aripiprazole. Both the patients stopped experiencing hyperhidrosis after their aripiprazole was discontinued. To the best of the knowledge of the author, no case of aripiprazole induced hyperhidrosis has been published in the literature.

Antidepressant imipramine diminishes stress-induced inflammation in the periphery and central nervous system and related anxiety- and depressive- like behaviors

In order to relieve anxiety and depression accompanying stress, physicians resort to tricyclic antidepressants, such as imipramine. We had previously shown that imipramine reversed stress-induced social avoidance behavior, and down-regulated microglial activation 24days after stress cessation. To further characterize the effects of imipramine on stress induced neuroimmune dysregulation and associated changes in behavior, the aims of this study were to determine if imipramine 1) ameliorated stress-induced inflammation in the periphery and central nervous system, and 2) prevented stress related anxiety- and depressive-like behaviors. C57BL/6 mice were treated with imipramine (15mg/kg) in their drinking water, and exposed to repeated social defeat (RSD). Imipramine attenuated stress-induced corticosterone and IL-6 responses in plasma. Imipramine decreased the percentage of monocytes and granulocytes in the bone marrow and circulation. However, imipramine did not prevent splenomegaly, stress-related increased percentage of granulocytes in this organ, and the production of pro-inflammatory cytokines in the spleen, following RSD. Moreover, imipramine abrogated the accumulation of macrophages in the brain in mice exposed to RSD. Imipramine blocked neuroinflammatory signaling and prevented stress-related anxiety- and depressive-like behaviors. These data support the notion that pharmacomodulation of the monoaminergic system, besides exerting anxiolytic and antidepressant effects, may have therapeutic effects as a neuroimmunomodulator during stress.

Antidepressants in the Treatment of Functional Dyspepsia: A Systematic Review and Meta-Analysis

BACKGROUND

Antidepressants have been empirically used in the treatment of functional dyspepsia (FD). However, results from recent clinical trials investigating their efficacy are conflicting. The aim of this study is to evaluate the efficacy of antidepressants in the management of FD in adults.

METHODS

Databases of MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials and BIOSIS Previews were searched for all randomized controlled trials (RCT) investigating efficacy of antidepressants in the management of FD in adult patients. Data of overall symptom unimproved and adverse events were compared between the antidepressants and placebo group.

RESULTS

The search strategy identified 432 citations. Of those, eight RCTs met the inclusion criteria and were included in the meta-analysis. The pooled relative risk (RR) of symptom unimproved with tricyclic antidepressants (TCAs) versus placebo was 0.76 (95% CI: 0.62 to 0.94, P = 0.01; I2 = 0%, P = 0.39). By contrast, selective serotonin reuptake inhibitors (SSRIs) did not show a benefit over placebo (RR = 1.00, 95% CI: 0.86 to 1.17, P = 0.95; I2 = 0%, P = 0.82). Adverse events were significantly more frequent among patients receiving antidepressants than those receiving placebos (RR = 1.64, 95% CI: 1.14 to 2.35, P = 0.007).

CONCLUSION

TCAs but not SSRIs, are effective in the treatment of FD, but antidepressants were also associated with more adverse events compared with placebo.

Clinical management following self-harm in a UK-wide primary care cohort

BACKGROUND

Little is known about the clinical management of patients in primary care following self-harm.

METHODS

A descriptive cohort study using data from 684 UK general practices that contributed to the Clinical Practice Research Datalink (CPRD) during 2001-2013. We identified 49,970 patients with a self-harm episode, 41,500 of whom had one complete year of follow-up.

RESULTS

Among those with complete follow-up, 26,065 (62.8%, 62.3-63.3) were prescribed psychotropic medication and 6318 (15.2%, 14.9-15.6) were referred to mental health services; 4105 (9.9%, CI 9.6-10.2) were medicated without an antecedent psychiatric diagnosis or referral, and 4,506 (10.9%, CI 10.6-11.2) had a diagnosis but were not subsequently medicated or referred. Patients registered at practices in the most deprived localities were 27.1% (CI 21.5-32.2) less likely to be referred than those in the least deprived. Despite a specifically flagged NICE 'Do not do' recommendation in 2011 against prescribing tricyclic antidepressants following self-harm because of their potentially lethal toxicity in overdose, 8.8% (CI 7.8-9.8) of individuals were issued a prescription in the subsequent year. The percentage prescribed Citalopram, an SSRI antidepressant with higher toxicity in overdose, fell sharply during 2012/2013 in the aftermath of a Medicines and Healthcare products Regulatory Agency (MHRA) safety alert issued in 2011.

CONCLUSIONS

A relatively small percentage of these vulnerable patients are referred to mental health services, and reduced likelihood of referral in more deprived localities reflects a marked health inequality. National clinical guidelines have not yet been effective in reducing rates of tricyclic antidepressant prescribing for this high-risk group.

Mirtazapine added to selective serotonin reuptake inhibitors for treatment-resistant depression in primary care (MIR trial): study protocol for a randomised controlled trial

BACKGROUND

People with depression are usually managed in primary care and antidepressants are often the first-line treatment, but only one third of patients respond fully to a single antidepressant. This paper describes the protocol for a randomised controlled trial (MIR) to investigate the extent to which the addition of the antidepressant mirtazapine is effective in reducing the symptoms of depression compared with placebo in patients who are still depressed after they have been treated with a selective serotonin reuptake inhibitor (SSRI) or serotonin and noradrenaline reuptake inhibitor (SNRI) for at least 6 weeks in primary care.

METHODS/DESIGN

MIR is a two-parallel group, multi-centre, pragmatic, placebo controlled, randomised trial with allocation at the level of the individual. Eligible participants are those who: are aged 18 years or older; are currently taking an SSRI/SNRI antidepressant (for at least 6 weeks at an adequate dose); score ≥ 14 on the Beck Depression Inventory (BDI-II); have adhered to their medication; and meet ICD-10 criteria for depression (assessed using the Clinical Interview Schedule-Revised version). Participants who give written, informed consent, will be randomised to receive either oral mirtazapine or matched placebo, starting at 15 mg daily for 2 weeks and increasing to 30 mg daily thereafter, for up to 12 months (to be taken in addition to their usual antidepressant). Participants, their GPs, and the research team will all be blind to the allocation. The primary outcome will be depression symptoms at 12 weeks post randomisation, measured as a continuous variable using the BDI-II. Secondary outcomes (measured at 12, 24 and 52 weeks) include: response (reduction in depressive symptoms (BDI-II score) of at least 50% compared to baseline); remission of depression symptoms (BDI-II <10); change in anxiety symptoms; adverse effects; quality of life; adherence to antidepressant medication; health and social care use, time off work and cost-effectiveness. All outcomes will be analysed on an intention-to-treat basis. A qualitative study will explore patients' views and experiences of either taking two antidepressants, or an antidepressant and a placebo; and GPs' views on prescribing a second antidepressant in this patient group.

DISCUSSION

The MIR trial will provide evidence on the clinical and cost-effectiveness of mirtazapine as an adjunct to SSRI/SNRI antidepressants for patients in primary care who have not responded to monotherapy.

TRIAL REGISTRATION

EudraCT Number: 2012-000090-23 (Registered January 2012); ISRCTN06653773 (Registered September 2012).

Dual Targeting of the Autophagic Regulatory Circuitry in Gliomas with Repurposed Drugs Elicits Cell-Lethal Autophagy and Therapeutic Benefit

The associations of tricyclic antidepressants (TCAs) with reduced incidence of gliomas and elevated autophagy in glioma cells motivated investigation in mouse models of gliomagenesis. First, we established that imipramine, a TCA, increased autophagy and conveyed modest therapeutic benefit in tumor-bearing animals. Then we screened clinically approved agents suggested to affect autophagy for their ability to enhance imipramine-induced autophagy-associated cell death. The anticoagulant ticlopidine, which inhibits the purinergic receptor P2Y12, potentiated imipramine, elevating cAMP, a modulator of autophagy, reducing cell viability in culture, and increasing survival in glioma-bearing mice. Efficacy of the combination was obviated by knockdown of the autophagic regulatory gene ATG7, implicating cell-lethal autophagy. This seemingly innocuous combination of TCAs and P2Y12 inhibitors may have applicability for treating glioma.

[FOCAL MOTOR SEIZURES AND STATUS EPILEPTICUS PROVOKED BY MIRTAZAPINE]

The seizure-provoking effect of the tetracyclic antidepressant mirtazapine is not a well-known adverse effect of the drug. The authors report on a 39-year-old non-epileptic patient who had been treated for depression with the usual daily dose of mirtazapine. Having increased the daily dose of the drug from 30 to 45 milligrams he experienced a few clonic seizures of the right lower limb. This symptom and insomnia erroneously intended the patient to further increase the daily dose of mirtazapine, which immediately resulted in the evolution of focal clonic status epilepticus in the same limb. After admission, this condition was recorded by video-EEG and abolished by intravenous administration of levetiracetam after the intravenous clonazepam had been ineffective. Discontinuation of mirtazapine and administration of carbamazepine resulted in completely seizure-free state that persisted even after carbamazepine treatment was terminated. The clinical and laboratory data indicate the seizure-provoking effect of mirtazapine in the reported case.

Distribution pattern of mirtazapine and normirtazapine in blood and CSF

RATIONALE

The aim of this study was to investigate the distribution pattern of mirtazapine and its metabolite normirtazapine (N-desmethylmirtazapine) in blood and cerebrospinal fluid (CSF).

OBJECTIVES AND METHODS

Concentrations of mirtazapine were measured in blood serum and CSF of 16 patients treated with daily doses of 7.5-60 mg. Daily doses were correlated with serum and CSF concentrations as well as serum levels with those in CSF.

RESULTS

Serum levels of mirtazapine and normirtazapine showed a strong relation to the daily dose of mirtazapine of r = +0.631 and r = +0.732, respectively (p < 0.01). Between the daily doses and the CSF levels of both mirtazapine and normirtazapine, we only found a trend-wise correlation (r = +0.535, p = 0.060). The correlation between mirtazapine and normirtazapine in serum and CSF was highly significant (r = +0.664, p = 0.005 and r = +0.885, p < 0.001, respectively). High discrepancies between (total) mirtazapine levels in serum and CSF indicate a low penetration into CSF with regard to the total serum concentration as the mean of the calculated penetration ratio was 0.16 (SD = 0.11). By correcting the penetration ratio for the plasma protein binding, the mean CSF/serum ratio for the unbound fraction was 1.05 (SD 0.72, range 0.56-3.19) indicating a high passage into CSF.

CONCLUSIONS

Findings indicate a good ability of mirtazapine and normirtazapine to overcome the blood-cerebrospinal fluid barrier and suggest a high ability to enter the brain with sufficient drug levels at the target sites within the brain contributing to clinical efficacy.

Tricyclic and SSRI usage influences the association between BMI and health risk factors

To determine if selective-serotonin reuptake inhibitors (SSRIs) and tricyclic antidepressants (TCAs) influence the association between obesity and cardiovascular disease risk, participants from the Third National Health and Nutrition Examination Survey (NHANES III; 1988-1992) and continuous NHANES (1999-2009, n = 18 274) were used. For a given body mass index (BMI), individuals taking SSRIs (n = 219) tended to have significantly better health risk profiles with lower systolic blood pressure (P = 0.002) and higher high-density lipoprotein (P = 0.003) compared with non-users. Conversely, those who used TCAs (n = 116) had significantly worse health risk profiles with higher diastolic blood pressure (P ≤ 0.0001) and triglycerides (P = 0.023) as compared with non-users for a given BMI. Insulin resistance (HOMA-IR) was higher in TCA users and those with larger BMIs, whereby the differences in insulin resistance between TCA users and non-users was greater with higher BMIs (interaction effect: P = 0.013). Furthermore, individuals taking SSRIs were less likely to have cardiovascular disease than non-users (odds ratio, 95% confidence interval = 0.50, 0.33-0.75) for a given BMI, with no differences by TCA use (odds ratio = 0.74, 0.44-1.24). SSRI and TCA use may alter how body weight relates with cardiovascular risk. When prescribing antidepressant medications, it may be necessary to monitor and consider body weight and cardiovascular risk profile of individual patients.

Electrocardiograms changes in children with functional gastrointestinal disorders on low dose amitriptyline

AIM: To study the effects of low dose amitriptyline on cardiac conduction in children.

METHODS: Secondary analysis of data obtained from a double-blind, randomized placebo-controlled trial, evaluating low dose amitriptyline in children with a diagnosis of functional abdominal pain, functional dyspepsia, and irritable bowel syndrome according to the Rome II criteria. Children 8-17 years of age were recruited from the pediatric gastroenterology clinics of 6 tertiary care centers in the United States. The electrocardiograms (EKGs) done prior to initiation of amitrityline and 1 mo after initiation of amitriptyline were examined. The changes in cardiac conduction were evaluated in patients and controls.

RESULTS: Thirty children were included in the study. There were 12 patients, ages 9-17 years of both genders, in the amitriptyline treatment group and 18 patients, ages 9-17 years of both genders, in the placebo treatment group. None of the patients had any baseline EKG abnormality. Amitriptyline use was associated with an increase in heart rate (P = 0.024) and QTc interval (P = 0.0107) as compared to pre-EKGs. Children in the placebo group were also noted to present a statistically significant increase in QTc interval (P = 0.0498). None of the patients developed borderline QTc prolongation or long-QT syndrome after they were started on amitriptyline.

CONCLUSION: The study findings suggest that once patients with functional gastrointestinal disorders have been screened for prolonged QTc interval on baseline EKG, they probably do not need a second EKG for reevaluation of cardiac conduction after starting low dose amitriptyline.

Mirtazapine-associated hyponatremia presenting as delirium

Though there is ample evidence for the association between selective serotonin reuptake inhibitors and hyponatremia, evidence for the relationship between mirtazapine and hyponatremia is scarce. We present a case of mirtazapine-induced hyponatremia in an adult patient, which was dose related.

The selective glucocorticoid receptor antagonist CORT 108297 decreases neuroendocrine stress responses and immobility in the forced swim test

Pre-clinical and clinical studies have employed treatment with glucocorticoid receptor (GR) antagonists in an attempt to limit the deleterious behavioral and physiological effects of excess glucocorticoids. Here, we examined the effects of GR antagonists on neuroendocrine and behavioral stress responses, using two compounds: mifepristone, a GR antagonist that is also a progesterone receptor antagonist, and CORT 108297, a specific GR antagonist lacking anti-progestin activity. Given its well-documented impact on neuroendocrine and behavioral stress responses, imipramine (tricyclic antidepressant) served as a positive control. Male rats were treated for five days with mifepristone (10mg/kg), CORT 108297 (30mg/kg and 60mg/kg), imipramine (10mg/kg) or vehicle and exposed to forced swim test (FST) or restraint stress. Relative to vehicle, imipramine potently suppressed adrenocorticotropin hormone (ACTH) responses to FST and restraint exposure. Imipramine also decreased immobility in the FST, consistent with antidepressant actions. Both doses of CORT 108297 potently suppressed peak corticosterone responses to FST and restraint stress. However, only the higher dose of CORT 108297 (60mg/kg) significantly decreased immobility in the FST. In contrast, mifepristone induced protracted secretion of corticosterone in response to both stressors, and modestly decreased immobility in the FST. Taken together, the data indicate distinct effects of each compound on neuroendocrine stress responses and also highlight dissociation between corticosterone responses and immobility in the FST. Within the context of the present study, our data suggest that CORT 108297 may be an attractive alternative for mitigating neuroendocrine and behavioral states associated with excess glucocorticoid secretion.

Amitriptyline overdose in emergency department of university hospital: evaluation of 250 patients

OBJECTIVE

The purpose of this study was to evaluate the patients with acute amitriptyline poisoning and investigate predictive factors for the development of life-threatening complications.

METHODS

Demographics, clinical, laboratory, and electrocardiographic (ECG) findings of 250 patients were evaluated retrospectively. Predictive parameters for the development of serious complications were studied.

RESULTS

Median age of patients was 14.6 years, of which, 70% of patients were female and 66% were in pediatric age group. The most common pathological clinical finding and laboratory abnormality were alteration of consciousness and hyponatremia. The rate of convulsive seizure, arrhythmia, and respiratory depression were 17 (6.8%), 16 (6.4%), and 11 (4.4%), respectively. These complications were more seen in pediatric patients than adults (15.8% and 1.2%). The incidence of hyponatremia was more in pediatric patients and severe poisoning groups (38.8 and 53.4%, respectively). The levels of amitriptyline and nortriptyline were significantly higher in the group with complications than the group without complications (p < 0.05). All adult patients were discharged with good prognosis. In pediatric age group, one patient was discharged with severe neurological sequelae and one patient died. QRS duration >100 ms, long corrected QT duration interval, and low Glasgow Coma Score (GCS) at admission were identified as independent risk factors for the development of life-threatening complications (odds ratio: 69.4, 1.9, and 1383, respectively; p < 0.05).

CONCLUSION

Amitriptyline poisoning may be associated with life-threatening complications, especially in pediatric age group and in patients with hyponatremia. Low GCS, presence of hyponatremia, high serum drug levels, and pathological ECG findings on admission may be helpful in predicting the development of complications and poor prognosis.

[Herpes zoster-induced neuralgia (neuropathy)]

Neuralgia (neuropathy) is the most common manifestation of herpes zoster (HZ). In spinal and cranial neuralgia, there are 3 types of pain: 1) spontaneous, persistent, burning pain; 2) intermittent sharp pain; 3) pain occurring with nonpainful stimulation. The skin exhibits areas of hypesthesia, anesthesia, and dysesthesia. Ophthalmic neuralgia (of the first branch of the trigeminal nerve) is encountered in 20% of HZ cases. HZ of the auricle and external auditory meatus concurrent with facial and vestibulocochlear neuropathy is diagnosed as Ramsay Hunt syndrome. Postherpetic neuralgia (neuropathy) is characterized by pain present for 3 months or more after the appearance of herpetic eruptions. Combined therapy involving the earlier use of antiviral agents, tricyclic antidepressants, analgesics, and neuromidine is the most effective option for HZ-induced neuralgia (neuropathy).

Side effects of antidepressants during long-term use in a naturalistic setting

Side effects of antidepressants are usually underreported in clinical trials and large scale naturalistic studies are restricted to six months of use. We examined the prevalence and nature of patient-perceived side effects and their determinants during long-term antidepressant use in a naturalistic setting. Subjects, aged 19 to 67 years, in the Netherlands Study of Depression and Anxiety were recruited from primary care and specialized mental health care covered 927 cases of single antidepressant use. In 64% of cases, on average, 2.9 side effects were reported. The number of side effects was higher when subjects had higher depression severity (OR=1.28; p=0.002), three or more psychiatric diagnoses (OR=1.97; p=0.02), higher dose (OR=1.44; p=0.006) and was lower when subjects were older (OR=0.83; p=0.02) and had longer duration of use (OR=0.94; p=0.04). Tricyclic antidepressants were associated with more side effects (OR=2.52; p=0.003) and, particularly, more anticholinergic effects, like dry mouth and constipation, as compared to selective serotonin reuptake inhibitors. Venlafaxine showed more profuse sweating (OR=1.79; p=0.007), whereas mirtazapine showed more weight gain and less sexual dysfunction (OR=0.36; p=0.03), as compared to selective serotonin reuptake inhibitors. Weight gain was associated with female gender (OR=1.76; p=0.004) and duration of use (OR=1.06; p=0.03). We show that antidepressant side effect, known from short-term studies, persist during long-term use and are associated with depression severity and antidepressant dose. A novel finding was that venlafaxine is associated with more profuse sweating and that weight gain appeared more specific in female users. Clinicians should be aware that, during long-term antidepressant use, side effects are common and persistent.

[Antidepressant treatment associated hyponatremia -- case report]

Hyponatremia is a potential side-effect of antidepressants that was observed most frequently in connection with compounds acting on the serotonin system. Risk of hyponatremia was found to be higher in the elderly. Authors report a case of a 65-year old male patient who was treated with venlafaxine-mirtazapine combination for recurrent depression. Severe hyponatremia, requiring intensive care, emerged in connection with the treatment. The authors emphasize the importance of the regular checking of serum sodium levels during antidepressant treatment, especially in elderly patients.

Meta-Analysis of Efficacy of Mirtazapine as an Adjunctive Treatment of Negative Symptoms in Schizophrenia

CONTEXT

Despite advances made in treating the positive symptoms of schizophrenia, treatment of negative symptoms remains an unmet therapeutic need. Adjunctive mirtazapine has shown promise for treatment of negative symptoms in several small clinical trials.

OBJECTIVE

To assess the efficacy of mirtazapine as an adjunctive treatment of negative symptoms in patients with chronic schizophrenia via meta-analysis.

DATA SOURCES

A systematic literature review of articles in English and Spanish was conducted in November 2011 by searching PubMed, the Cochrane Library, the Clinical Trial Registry of the NIH, and SIGLE (System for Grey Literature in Europe). Free text search terms for PubMed were "schizophrenia," "negative symptoms" and "mirtazapine." Publication date was not a limitation.

STUDY SELECTION

Studies of people with schizophrenia/schizoaffective disorder were included in the meta-analysis if they were randomized, double-blind, and used the Positive and Negative Syndrome Scale (PANSS) as an outcome measure. Nine studies were initially identified. Five studies were included in the meta-analysis; 1 study was excluded for not using the PANSS, 3 were excluded as representing duplicate publications and open-label phases of one of the selected randomized control trials. Studies varied in the quality of their selection for participants with primary negative symptoms.

RESULTS

Three of the 5 studies showed significant improvement in negative symptoms individually. The overall analysis showed improvement in negative symptoms with an effect size of 1.00 (0.084-1.918), which was statistically significant (p=0.032). Data from the negative symptoms subscale of the PANSS from 169 subjects was used in a forest plot to illustrate the relative strength of treatment effects. The variation in standard median deviation (SMD) attributable to heterogeneity was 27.35 %, indicating a high degree of heterogeneity.

CONCLUSIONS

This meta-analysis supports the hypothesis that adding mirtazapine to treatment with antipsychotics can improve negative symptoms in schizophrenia. However, additional studies with more stringent negative symptom selection criteria and homogeneous use of antipsychotics are needed.

An update on the drug treatment of neuropathic pain. Part 1: antidepressants. Drug Ther Bull. 2012;50:114-117. [PMID: 23065751 DOI: 10.1136/dtb.2012.10.0133]

Neuropathic pain refers to pain that arises as a direct consequence of a lesion or disease affecting the somatosensory nervous system.(1) Many cases of neuropathic pain run a chronic course, and treatment may be difficult because commonly used analgesics, including NSAIDs and to some extent opioids, are often ineffective. In addition, the use of other pharmacological treatments can be limited by unwanted effects. Management requires a multidisciplinary approach and may involve the use of drug therapy (including antidepressants, anticonvulsants and opioids) with non-pharmacological interventions (including psychological therapies, transcutaneous electrical nerve stimulation and interventional procedures). This month and next month we review the drug treatment of neuropathic pain. In this first part we discuss neuropathic pain and the use of antidepressants.

Fractures in users of antidepressants and anxiolytics and sedatives: effects of age and dose

SUMMARY

Antidepressants have been associated with fractures. In a case-control study, increasing age was associated with more fractures in users of selective serotonin reuptake inhibitors and tricyclic antidepressants, whereas for anxiolytics and sedatives, more fractures were seen among the younger users. Depression per se did not seem associated with fractures.

INTRODUCTION

This study aims to study the effects of age and dose of selective serotonin reuptake inhibitors (SSRI), tricyclic antidepressants (TCA) and anxiolytics/sedatives on fracture risk.

METHODS

The study was designed as a case-control study. From the Danish National Health Service, we identified 124,655 fracture cases and 373,962 age- and gender-matched controls. Crude odds ratios were estimated, and propensity score adjustment was used to minimise confounding by indication.

RESULTS

A higher risk of fractures was associated with an increasing dose of anxiolytics and sedatives; the highest excess risk was present in the age stratum below 40 years of age (p < 0.01), and thereafter, the excess risk of fractures declined with age. For SSRI, a growing excess risk of fractures was seen with both increasing dose and age. Regarding TCA, no particular trend with age was present. However, an increasing risk of fractures was associated with increasing TCA dose in the age group above 60 years. Finally, for other antidepressants, no particular trend with age or dose was observed. In our data, a hospital diagnosis of depression or manic depression was associated with fewer fractures.

CONCLUSION

Caution should be shown upon prescription of SSRI to older subjects. A hospital diagnosis of depression or manic depression and thus potentially a more severe disease was not a risk factor for fractures.

[The combined therapy with valdoxan and amitriptyline of treatment resistant somatized depression]

The combined treatment with valdoxan and amitriptyline has been suggested as one of the possible variants to overcome treatment resistance in somatized depression. A study design was based on the rhythmological model of depression which clinically characterized by altered sleep-awakeness cycles. According to this notion, 36 patients were divided into two groups by the presence (20 patients) or absence (16 patients) of severe sleep disorders. The combined treatment was more effective in the first group of patients with insomnia which was an indicator of altered sleep-awakeness cycles.

Chronic pain perspectives: Treating herpes zoster and postherpetic neuralgia: an evidence-based approach

When are corticosteroids appropriate for patients with herpes zoster? Which tricyclics are best for frail and elderly patients with PHN pain? And when should you consider opioids?

[Case of successful management with mirtazapine for prolonged pain after esophagectomy]

This case report describes a successful outcome of mirtazapine treatment in a patient with difficult post-thoracotomy pain. A 63-year-old man received thoracotomy for the resection of esophageal tumor. The pain continued 2 years after the operation. Allodynia was present in the region of the intercostal nerves from the surgical wound. Remedies such as clonazepam, amitriptyline, gabapentin, and acetaminophen were not effective, and epidural block effect was only temporal. The patient experienced a reduction in shooting pain after taking pregabalin; however, he still suffered from persistent pain and, mirtazapine was additionally administrated. One month after this, shooting and persistent pain was reduced, and the patient's appetite was improved, which had been present since the thoracotomy. Since then, his weight slightly increased and the administration of mirtazapine was stopped in accordance with the patient's request. The pain became worse again. Therefore, mirtazapine, commonly used as an antidepressant agent, was considered to be beneficial for neuropathic pain as an analgesic adjuvant.

Assessment of anxiolytic and panicolytic effects of dichloromethane fraction from stems of Kielmeyera coriacea

Kielmeyera coriacea Mart. (Calophyllaceae) is known popularly as "Pau Santo". The hydroethanolic extract (HE) of Kielmeyera coriacea stems and its semi-pure dichloromethane (DCM) constituent produced an antidepressant-like effect in rats. The purpose of this study was to investigate the effects of repeated administration (21 days) by gavage of the DCM fraction (5, 10 or 15mg/kg) in rats submitted to the elevated T-maze (ETM), a model of generalized anxiety and panic disorders. The tricyclic antidepressant imipramine (15mg/kg) was used as a positive control. Rat locomotion was assessed using the open field test (OFT) following each drug treatment. The 2-hydroxy-1-methoxyxanthone (1), aucuparin (2), swertinin (3), 1,3,7-trihydroxy-2-(3-methylbut-2-enyl)-xanthone (4) and 1,3,5-trihydroxy-2-(3-methylbut-2-enyl)-xanthone (5) were identified in DCM fraction, and suggest that the xanthone (4) is related with the antidepressant-like profile of this plant. Pharmacological evaluation showed that DCM fraction (10 and 15 mg/kg) decreased the inhibitory avoidance latency from the closed arm and increased the one-way escape latency from the open arm in the ETM, which is indicative of anxiolytic and panicolytic effects, respectively, as occurs with the positive control, imipramine (15 mg/kg), when compared to their control group (vehicle). Locomotor activity was not significantly altered by the different treatments. This study suggests that the DCM fraction from stems of Kielmeyera coriacea can be an important therapeutic alternative in the treatment of anxiety disorders, such as generalized anxiety and panic disorders.

The antinociceptive effects of intravenous tianeptine in colorectal distension-induced visceral pain in rats: the role of 5-HT₃ receptors

Tianeptine is an unusual tricyclic antidepressant drug. In this study, we aimed to investigate the antinociceptive effect of tianeptine on visceral pain in rats and to determine whether possible antinociceptive effect of tianeptine is mediated by serotonergic (5-HT(2,3)) and noradrenergic (α(1,2)) receptor subtypes. Male Sprague Dawley rats (250-300 g) were supplied with a venous catheter, for drug administrations, and enameled nichrome electrodes, for electromyography, at external oblique musculature. Colorectal distension (CRD) was employed as the noxious visceral stimulus and the visceromotor response (VMR) to CRD was quantified electromyographically before and 5, 15, 30, 60, 90 and 120 min after tianeptine administration. Antagonists were administered 10 min before tianeptine for their ability to change tianeptine antinociception. Intravenous administration of tianeptine (2.5-20 mg/kg) produced a dose-dependent reduction in VMR. Administration of 5-HT(3) receptor antagonist ondansetron (0.5, 1 and 2 mg/kg), but not 5-HT(2) receptor antagonist ketanserine (0.5, 1 and 2 mg/kg), reduced the antinociceptive effect of tianeptine (10mg/kg). In addition, administration of α(1)-adrenoceptor antagonist prazosin (1 mg/kg) or α(2)-adrenoceptor antagonist yohimbine (1 mg/kg) did not cause any significant effect on the tianeptine-induced antinociception. Our data indicate that intravenous tianeptine exerts a pronounced antinociception against CRD-induced visceral pain in rats, and suggests that the antinociceptive effect of tianeptine appears to be mediated in part by 5-HT(3) receptors, but does not involve 5-HT(2) receptors or α-adrenoceptors.

Case series of perimenopausal women with insomnia treated with mirtazapine followed by prolonged-release melatonin add-on and monotherapy

OBJECTIVES

The sedating antidepressant mirtazapine is used off label for insomnia in perimenopausal women. Despite its apparent efficacy, mirtazapine causes significant increases in appetite and weight gain. Prolonged-release melatonin (PRM) is approved for primary insomnia in patients aged 55 years and older. A clinical experience with PRM add-on to mirtazapine in facilitating mirtazapine withdrawal while maintaining improved sleep quality and abrogating weight gain in perimenopausal women with insomnia is described.

METHODS

Eleven perimenopausal women (ages 45-52; FSH = 53 ± 8; normal BMI, 22.9 ± 0.6) with insomnia, who do not suffer from depression as assessed by the Hamilton scale, were treated with 15 mg mirtazapine (Remeron®) for 2-4 weeks. PRM, 2 mg (Circadin®), was then added on, and mirtazapine was tapered off for another 1-3 months. Prospective data on body weight and subjectively assessed sleep quality and well-being (assessed by the Pittsburgh Sleep Quality Index, PSQI, and Well-Being Index, WHO-5, respectively) were collected before, during, and at the end of the treatment.

RESULTS

Sleep quality ratings improved significantly (by 103% on average) during combined mirtazapine and PRM intake and 180% during subsequent intake of PRM alone or together with very low doses of mirtazapine (P < 0.05 for all). Well-being significantly improved by 83% during the treatment. Seven of 11 women demonstrated weight gain following mirtazapine intake, five of whom have started to reduce weight following mirtazapine withdrawal and PRM intake. No adverse events were reported.

CONCLUSION

Application of mirtazapine followed by PRM add-on and monotherapy improves sleep in perimenopausal women while evading mirtazapine-induced weight gain. These results warrant further investigation of a larger population in controlled clinical trials.

Interstitial cystitis/painful bladder syndrome

Interstitial cystitis/painful bladder syndrome affects more than 1 million persons in the United States, but the cause remains unknown. Most patients with interstitial cystitis/painful bladder syndrome are women with symptoms of suprapubic pelvic and/or genital area pain, dyspareunia, urinary urgency and frequency, and nocturia. It is important to exclude other conditions such as infections. Tests and tools commonly used to diagnose interstitial cystitis/painful bladder syndrome include specific questionnaires developed to assess the condition, the potassium sensitivity test, the anesthetic bladder challenge, and cystoscopy with hydrodistension. Treatment options include oral medications, intravesical instillations, and dietary changes and supplements. Oral medications include pentosan polysulfate sodium, antihistamines, tricyclic antidepressants, and immune modulators. Intravesical medications include dimethyl sulfoxide, pentosan polysulfate sodium, and heparin. Pentosan polysulfate sodium is the only oral therapy and dimethyl sulfoxide is the only intravesical therapy with U.S. Food and Drug Administration approval for the treatment of interstitial cystitis/painful bladder syndrome. To date, clinical trials of individual therapies have been limited in size, quality, and duration of follow-up. Studies of combination or multimodal therapies are lacking.

Cost-effectiveness analysis of a new 8% capsaicin patch compared to existing therapies for postherpetic neuralgia

OBJECTIVE

The purpose of this study was to compare the cost effectiveness of a new 8% capsaicin patch, compared to the current treatments for postherpetic neuralgia (PHN), including tricyclic antidepressants (TCAs), topical lidocaine patches, duloxetine, gabapentin, and pregabalin.

METHODS

A 1-year Markov model was constructed for PHN with monthly cycles, including dose titration and management of adverse events. The perspective of the analysis was from a payer perspective, managed-care organization. Clinical trials were used to determine the proportion of patients achieving at least a 30% improvement in PHN pain, the efficacy parameter. The outcome was cost per quality-adjusted life-year (QALY); second-order probabilistic sensitivity analyses were conducted.

RESULTS

The effectiveness results indicated that 8% capsaicin patch and topical lidocaine patch were significantly more effective than the oral PHN products. TCAs were least costly and significantly less costly than duloxetine, pregabalin, topical lidocaine patch, 8% capsaicin patch, but not gabapentin. The incremental cost-effectiveness ratio for the 8% capsaicin patch overlapped with the topical lidocaine patch and was within the accepted threshold of cost per QALY gained compared to TCAs, duloxetine, gabapentin, and pregablin. The frequency of the 8% capsaicin patch retreatment assumption significantly impacts its cost-effectiveness results. There are several limitations to this analysis. Since no head-to-head studies were identified, this model used inputs from multiple clinical trials. Also, a last observation carried forward process was assumed to have continued for the duration of the model. Additionally, the trials with duloxetine may have over-predicted its efficacy in PHN. Although a 30% improvement in pain is often an endpoint in clinical trials, some patients may require greater or less improvement in pain to be considered a clinical success.

CONCLUSIONS

The effectiveness results demonstrated that 8% capsaicin and topical lidocaine patches had significantly higher effectiveness rates than the oral agents used to treat PHN. In addition, this cost-effectiveness analysis found that the 8% capsaicin patch was similar to topical lidocaine patch and within an accepted cost per QALY gained threshold compared to the oral products.