Effect of zinc supplementation on antidepressant therapy in unipolar depression: a preliminary placebo-controlled study.
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A growing body of evidence implicates a derangement of zinc homeostasis in mood disorders. In general, unipolar depression is connected with low blood zinc levels that are increased by effective antidepressant therapy. A placebo-controlled, double blind pilot study of zinc supplementation in antidepressant therapy was conducted in patients who fulfilled DSM IV criteria for major (unipolar) depression. Patients received zinc supplementation (6 patients; 25 mg of Zn2+ once daily) or placebo (8 patients) and were treated with standard antidepressant therapy (tricyclic antidepressants, selective serotonin reuptake inhibitors). Hamilton Depression Rating Scale (HDRS) and Beck Depression Inventory (BDI) were used to assess efficacy of antidepressant therapy, and patients' status was evaluated before the treatment and 2, 6 and 12 weeks after its commencement. Antidepressant treatment significantly reduced HDRS scores by the 2nd week of treatment in both groups, and lowered BDI scores at the 6th week in zinc-treated group. Zinc supplementation significantly reduced scores in both measures after 6- and 12-week supplementation when compared with placebo treatment. This preliminary study is the first demonstration of the benefit of zinc supplementation in antidepressant therapy. The mechanism(s) may be related to modulation of glutamatergic or immune systems by zinc ion. (+info)
Influence of the light schedule on the toxicity of amitriptyline in chick embryos.
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The cardiac toxicity of amitriptyline and the effect of the light schedule on it were studied in chick embryos. Fertilized eggs of White Leghorns were incubated under dark conditions and investigated, on two occasions, in the light phase and in the dark phase. Amitriptyline was injected into the air sac of fertilized eggs on the 16th day of incubation. Electrocardiograms were recorded 0 to 60 min after the injection. After the administration of amitriptyline 1 mg/egg in the light phase, the heart rate did not differ compared with that in controls. However, the heart rate was significantly decreased by the administration of amitriptyline 2.5 mg/egg and 5 mg/egg in the light phase. The heart rate was significantly decreased by the administration of amitriptyline 1 mg/egg under dark conditions. In addition, arrhythmia was produced by the administration of amitriptyline under dark conditions. These findings indicate that manipulation of the light schedule has a marked influence on the toxicity of amitriptyline in chick embryos. (+info)
Treatment of fibromyalgia with cyclobenzaprine: A meta-analysis.
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OBJECTIVE: To systematically review the effectiveness of cyclobenzaprine in the treatment of fibromyalgia. METHODS: Articles describing randomized, placebo-controlled trials of cyclobenzaprine in people with fibromyalgia were obtained from Medline, EMBase, Psyclit, the Cochrane Library, and Federal Research in Progress Database. Unpublished literature and bibliographies were also reviewed. Outcomes, including global improvement, treatment effects on pain, fatigue, sleep, and tender points over time, were abstracted. RESULTS: Five randomized, placebo-controlled trials were identified. The odds ratio for global improvement with therapy was 3.0 (95% confidence interval [95% CI] 1.6-5.6) with a pooled risk difference of 0.21 (95% CI 0.09-0.34), which calculates to 4.8 (95% CI 3.0-11) individuals needing treatment for 1 patient to experience symptom improvement. Pain improved early on, but there was no improvement in fatigue or tender points at any time. CONCLUSION: Cyclobenzaprine-treated patients were 3 times as likely to report overall improvement and to report moderate reductions in individual symptoms, particularly sleep. (+info)
Analytical application of the reactions of amitriptyline with eriochrome cyanine R and pyrocatechol violet.
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Eriochrome cyanine R (ECR) and pyrocatechol violet (PCV) have been tested as reagent for the determination of amitriptyline (AMT). They react in aqueous media with AMT forming coloured compounds sparingly soluble in walter. Optimal conditions for the reaction have been established and new extractive-spectrophotometric methods have been developed for the determination of amitriptyline. It can be assayed in the concentration range 8.0-80.0 microg/ml for the ECR method and in the range 1.5-15.0 microg/ml in the case of PCV. The methods were applied to the determination of amitriptyline in albumin and pharmaceutical preparations. The UV-VIS studies of the reagents and the formed compounds were performed. (+info)
Glutathione S-transferase pi as a target for tricyclic antidepressants in human brain.
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GST pi, the main glutathione S-transferase isoform present in the human brain, was isolated from various regions of the brain and the in vitro effect of tricyclic antidepressants on its activity was studied. The results indicated that amitripyline and doxepin--derivatives of dibenzcycloheptadiene, as well as imipramine and clomipramine--derivatives of dibenzazepine, inhibit the activity of GST pi from frontal and parietal cortex, hippocampus and brain stem. All these tricyclics are noncompetitive inhibitors of the enzyme with respect to reduced glutathione and noncompetitive (amitripyline, doxepin) or uncompetitive (imipramine, clomipramine) with respect to the electrophilic substrate. Their inhibitory effect is reversible and it depends on the chemical structure of the tricyclic antidepressants rather than on the brain localization of the enzyme. We conclude that the interaction between GST pi and the drugs may reduce their availability in the brain and thus affect their therapeutic activity. On the other hand, tricyclic antidepressants may decrease the efficiency of the enzymatic barrier formed by GST and increase the exposure of brain to toxic electrophiles. Reactive electrophiles not inactivated by GST may contribute in adverse effects caused by these drugs. (+info)
Peripheral nerve injury sensitizes the response to visceral distension but not its inhibition by the antidepressant milnacipran.
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BACKGROUND: Manipulations that cause hypersensitivity to visceral stimuli have been shown to also result in hypersensitivity to somatic stimuli coming from convergent dermatomes, but the converse has not been examined. The authors tested whether lumbar spinal nerve ligation in rats, a common model of neuropathic pain that results in hypersensitivity to somatic stimuli, also leads to hypersensitivity to visceral stimuli coming from convergent dermatomes and whether pharmacology of inhibition differed between these two sensory modalities. METHODS: Female Sprague-Dawley rats were anesthetized, and the left L5 and L6 spinal nerves were ligated. Animals received either intrathecal saline or milnacipran (0.1-3 microg), and withdrawal thresholds to mechanical testing in the left hind paw, using von Frey filaments, and visceral testing, using balloon colorectal distension, were determined. RESULTS: Nerve ligation resulted in decreases in threshold to withdrawal to somatic mechanical stimulation (from 13 +/- 1.8 g to 2.7 +/- 0.7 g) and also in decreases in threshold to reflex response to visceral stimulation (from 60 mmHg to 40 mmHg). Intrathecal milnacipran increased withdrawal threshold to somatic stimulation in a dose-dependent manner but failed to alter the response to noxious visceral stimulation. CONCLUSIONS: Injury of nerves innervating somatic structures enhances nociception from stimulation of viscera with convergent input from nearby dermatomes, suggesting that somatic neuropathic pain could be accompanied by an increased likelihood of visceral pain. Lack of efficacy of the antidepressant milnacipran against visceral stimuli suggests that visceral hypersensitivity may not share the same pharmacology of inhibition as somatic hypersensitivity after nerve injury. (+info)
Synergistic antinociceptive effect of amitriptyline and morphine in the rat orofacial formalin test.
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BACKGROUND: Combination therapy is often used to increase the clinical utility of analgesic agents. The coadministration of two compounds may achieve analgesia at doses lower than those required for either compound alone, leading to enhanced pain relief and reduction of adverse effects. Herein, the authors describe the effect of coadministration of morphine and amitriptyline on cutaneous orofacial inflammatory pain in rats. METHODS: Amitriptyline, morphine, or the combination of amitriptyline and morphine was administered systemically to rats, and antinociceptive effects were determined by means of the rat orofacial formalin test. Isobolographic analysis was used to define the nature of the interactions between morphine and amitriptyline. RESULTS: Amitriptyline as well as morphine produced a dose-related inhibition in the first phase and the second phase of rubbing activity. ED50 values against rubbing behavior were 14.6 mg/kg (95% confidence interval, 10.2-33.5 mg/kg) and 1.3 mg/kg (95% confidence interval, 1.0-1.7 mg/kg) for amitriptyline and morphine, respectively. Combinations of increasing fractional increments of amitriptyline and morphine ED50 doses produced a synergistic effect against rubbing behavior, as revealed by isobolographic analysis. CONCLUSIONS: The current study suggests that systemic amitriptyline and morphine synergistically inhibit cutaneous orofacial inflammatory pain in rats. (+info)
Phase Ia and Ib study of amitriptyline for ulnar nerve block in humans: side effects and efficacy.
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BACKGROUND: The antidepressant amitriptyline is used as an adjuvant in the treatment of chronic pain conditions. Among its many actions, this drug also blocks ion channels, such as Na channels. Preliminary animal studies suggested that amitripty-line would be a longer-lasting local anesthetic than bupivacaine, with potentially fewer side effects. Therefore, the authors investigated the adverse effects and effectiveness of this drug when given for ulnar nerve blockade in human volunteers. METHODS: After obtaining written institutional review board approval and informed consent, a typical phase Ia trial was conducted by administration to the ulnar nerve at the level of the wrist in an open-label, dose-escalating fashion. Amitripty-line hydrochloride, 4 ml, at concentrations of 5, 10, and 20 mM (n = 4-9/group) was used for each volunteer. If no major side effects and nerve block were encountered, comparison in a randomized, double-blinded trial of amitriptyline (20 mM) to placebo and bupivacaine (4 mM) (n = 4-9/group), was to follow. A blunt needle was used to grade the pain, and motor blockade was assessed by the Froment test. RESULTS: There was no significant statistical difference in terms of side effects (pain, swelling, erythema, and sedation) among any groups. The analgesic effects of 20 mM amitriptyline and 4 mm bupivacaine solution were significantly higher than those of the placebo solution. CONCLUSIONS: Because of the lack of evidence that amitripty-line provides better nerve blockade than current local anesthetics and the potential for neurotoxicity, its use for peripheral nerve blockade in humans seems limited. (+info)