Relapse Prevention in Major Depressive Disorder After Successful Acute Electroconvulsive Treatment: a 6-month Double-blind Comparison of Three Fixed Dosages of Escitalopram and a Fixed Dose of Nortriptyline - Lessons from a Failed Randomised Trial of the Danish University Antidepressant Group (DUAG-7).

INTRODUCTION: Electroconvulsive treatment (ECT) is an effective treatment for severe depression but carries a risk of relapse in the following months. METHODS: Major depressive disorder patients in a current episode attaining remission from ECT (17-item Hamilton Depression Rating Scale (HAM-D17) score≤9) received randomly escitalopram 10 mg, 20 mg, 30 mg or nortriptyline 100 mg as monotherapies and were followed for 6 months in a multicentre double-blind set-up. Primary endpoint was relapse (HAM-D17≥16). RESULTS: As inclusion rate was low the study was prematurely stopped with only 47 patients randomised (20% of the planned sample size). No statistically significant between-group differences could be detected. When all patients receiving escitalopram were compared with those receiving nortriptyline, a marginal superiority of nortriptyline was found (p=0.08). One third of patients relapsed during the study period, and one third completed. DISCUSSION: Due to small sample size, no valid efficacy inferences could be made. The outcome was poor, probably due to tapering off of non-study psychotropic drugs after randomisation; this has implications for future study designs. ClinicalTrials.gov Identifier: NCT00660062.

Effects of treatment with a lithium-imipramine combination on components of adenylate cyclase in the cerebral cortex of the rat.

This study was aimed at investigating the effects of treatment with a lithium-imipramine combination on the activity of adenylate cyclase in membranes from the cerebral cortex of the rat. Treatment with (1) lithium for 2 weeks, yielding a level of lithium in serum of 0.54 +/- 0.12 mmol/l, (2) imipramine for 4 weeks (10 mg/kg i.p. twice per day) and (3) a combination of the two drugs reduced isoprenaline-induced stimulation of adenylate cyclase by GTP, with a greater decrement with the combined treatment. None of the treatments exerted any effect on the activity of the enzyme stimulated by GTP alone. Lithium ex vivo inhibited the calcium (Ca2+)- and Gpp(NH)p-stimulated activity of adenylate cyclase, but imipramine ex vivo did not affect the activity of adenylate cyclase, stimulated by these activators. The lithium-imipramine treatment reduced Ca2(+)- and Gpp(NH)p-stimulated activity of adenylate cyclase, but this was not different from that observed in the lithium-treated group. In conclusion, the beta-adrenoceptor-stimulated adenylate cyclase was affected markedly by administration of lithium and imipramine together. In contrast to lithium ex vivo, imipramine ex vivo did not impair the activity of either the guanine nucleotide regulatory protein or the catalytic subunit, since no change in activity was observed in the presence of beta,gamma-imidoguanosine-5' triphosphate (Gpp(NH)p) or Ca2+. Furthermore, lithium ex vivo exerted its post-receptor effects on the adenylate cyclase, independent of imipramine. The decrement in activity of beta-adrenergic adenylate cyclase, induced by administration of the two drugs together may partly be involved in the therapeutic action of the augmentation of antidepressants by lithium in refractory depression.

Fluoride-stimulated adenylate cyclase activity in rat brain following chronic treatment with psychotropic drugs.

Chronic treatment with imipramine and reserpine increased fluoride-stimulated activity of adenylate cyclase in homogenates of cerebral cortex and "limbic" forebrain of the rat. Concomitant treatment with lithium counteracted this effect, while lithium alone had no effect on the activity of adenylate cyclase.

3,4-O-diacetylisoproterenol. Preparation, structure proof, and beta-receptor effect.

Direct acetylation of isoproterenol by selective O-acetylation using CH3COCl/CF3COOH was shown to lead to the formation of 2-(3,4-diacetoxyphenyl)-2-chloro-N-isopropyl-1-ethanamine and not to 3,4-O-diacetylisoproterenol. The latter was prepared by reduction of 3,4-diacetoxy(2-isopropylamino)acetophenone and its structure confirmed by IR, 1H, 13C NMR, mass spectral, and elemental analysis. The two compounds were tested for activity on beta-receptors. Efficacy and affinity on beta 1-receptors were found identical with the effect of isoproterenol. So was efficacy on beta2-receptors, while affinity was lower for the chloro compounds than for isoproterenol and diacetylisoproterenol which exhibited identical affinity.

Characterization of human platelet beta-adrenoceptors.

The widespread use of beta-adrenoceptor antagonists against hypertension, angina pectoris and migraine or as a preventive treatment after myocardial infarction has encouraged us to investigate the effects of these drugs on platelet function. The aim of this study was to examine whether beta-blocking drugs interfere with platelet beta- adrenoceptors and whether this dependency is related to their selectivity for beta-adrenoceptor subtypes. Beta-adrenoceptor stimulation of human platelets with isoprenaline increased cyclic AMP (cAMP), which is known to inhibit platelet aggregation. Furthermore, our studies showed that cAMP formation in vitro was stimulated by non-selective and beta 2-selective agonists, but not by the predominant beta 1-agonist prenalterol. Isoprenaline- stimulated cAMP formation was blocked by the non- selective beta-adrenoceptor antagonists propranolol, timolol, and alprenolol, while the beta 1-selective antagonists atenolol and metoprolol had no influence on an isoprenaline-induced cAMP formation. Receptor binding studies using (3H)-dihydroalprenolol revealed an IC50 value for propranolol of 85 nM, while metoprolol only displaced the bound (3H)-dihydroalprenolol at far higher concentrations (IC50, 20 microM). We conclude that the human platelet beta-adrenoceptors are mainly of the beta 2- subtype and that beta-adrenoceptor antagonists, especially the non-selective antagonists interfere with platelet function assessed as platelet cAMP formation.

Enhanced histamine- and beta-adrenoceptor-mediated cyclic AMP formation in leukocytes from patients with endogenous depression.

Beta-adrenoceptor-mediated cyclic AMP formation was found to be increased in leukocytes from manic-depressive patients during untreated depression when compared with euthymic patients treated with antidepressants. The difference was dependent on the stimulation used (isoprenaline or a combination of noradrenaline and phentolamine) and was only significant when the combination was used. Histamine-stimulated cyclic AMP formation in leukocytes was enhanced in patients with untreated depression, both when compared with euthymic patients suffering from manic-depressive illness, with or without treatment with antidepressant drugs, and also when compared with control persons without any known psychiatric disease. Although at variance with the results of some other studies on the same topic, the results of the present study indicate that changes in receptor function in leukocytes may be a state-dependent marker in depressive illness.

Increased polymorphonuclear leukocyte cGMP levels induced by the human lympholine, leukocyte migration inhibitory factor (LIF).

The possible involvement in vitro of 3', t'-cyclic GMP (cGMP) in the mechanism of action of the lymphokine, leukocyte migration inhibitory factor (LIF), was investigated. Partially purified LIF-rich supernatants, but not their control counterparts, induced a 2-fold increase in the cGMP levels of purified human polymorphonuclear (NMN) leukocytes. The effect was no influenced by heat-inactivated horse serum; it was manifested within 3 min of exposure to LIF and it subsided within 180 min. LIF and the supernatant factor responsible for the cGMP-generating effect were both rendered inactive by treatment with the serine esterase and protease inhibitor, phenylmethylsulfonyl fluoride, indicating that these factors are closely related, if not identical. A potent phosphodiesterase inhibitor, dipyridamole (2 x 10(-4) M), induced a 3- to 5-fold increase in PMN leukocyte cGMP levels, but combined treatment with purified LIF and dipyridamole did not add to this effect. This suggests that the cGMP-generating factor acts on the biochemical pathway that degrades cGMP.

The effect of lithium in vitro and in vivo on dopamine-sensitive adenylate cyclase activity in dopaminergic areas of the rat brain.

Lithium (5 and 20 mM) was found to inhibit the dopamine-stimulated cyclic AMP formation in homogenates from rat striatum and olfactory tubercle, leaving basal and fluoride-stimulated activities unaffected. The inhibition of dopamine-stimulated adenylate cyclase was non-competitive and dose-dependent. However, in rats treated with lithium for four weeks, no alterations were found in basal, fluoride- and dopamine-stimulated adenylate cyclase activities. It is suggested that lithium interferes with hormonal stimulation of adenylate cyclase activity by an interaction with the process regulating the transfer of the receptor-hormone stimulus to the adenylate cyclase enzyme.

Adenylate cyclase activity in corpus striatum of rats with porto-caval anastomosis.

Altered catecholamine receptor sites within the striatum have been proposed to be an important pathogenetic factor in hepatic and porto-systemic encephalopathy and coma. The unstimulated, fluoride-, norepinephrine- and dopamine-stimulated adenylate cyclase activity were measured in the corpus striatum of rats with a four weeks old end-to-side porto-caval anastomosis. There was no difference in unstimulated, fluoride- or hormone-stimulated adenylate cyclase activity between porto-caval shunted and sham-operated rats. The in vitro dose-response curves of norepinephrine and dopamine were similar in both groups of animals. Half-maximum and maximum stimulation were achieved in shunted and sham-operated rats by identical concentrations of norepinephrine and dopamine, respectively. The results indicate that neither changes in unstimulated adenylate cyclase activity nor changes in the response of adenylate cyclase activity to fluoride, norepinephrine and dopamine had developed in the rats at the stage studied.

Steady-state levels of imipramine and its metabolites: significance of dose-dependent kinetics.

Seventeen hospitalized patients (age 39-66 years), received a loading dose of 100 mg imipramine HCl and then 50 mg b.i.d. The 12-h plasma concentration at steady-state varied between 40-637 nmol/l for imipramine, 49-1148 nmol/l for desipramine and 89-1603 nmol/l for imipramine + desipramine. Guided by plasma level monitoring, a final therapeutic plasma level between 548-910 nmol/l for imipramine + desipramine was achieved (therapeutic dose range: 50-400 mg/day). Mean time to reach the therapeutic level was 19 days. The mean 2-OH-imipramine/imipramine ratio was 0.24 and mean 2-OH-desipramine/desipramine ratio was 0.56. There was a significant intrapatient correlation between the two ratios, both during 100 mg imipramine/d and at the therapeutic dose level. A low ratio was associated with high imipramine and particularly with a high desipramine level. Well defined steady state levels were established at two different dose levels in 12 patients and at three dose levels in 5 patients. With increasing dose there was a marked and disproportionate rise in the desipramine level and to some extent in the imipramine level. Saturation of imipramine and desipramine hydroxylation appeared to be responsible for the dose-dependent kinetics. Concomitant treatment with levomepromazine and perphenazine in one patient resulted in a significant rise both in imipramine and desipramine concentration, apparently due to inhibition of the hydroxylation. Eleven out of twelve endogenously depressed patients responded completely to treatment, whereas the response was poor in the non-endogenously depressed patients despite optimal drug levels.

Cyclic AMP phosphodiesterase activity in rat brain following chronic treatment with lithium, imipramine, reserpine, and combinations of lithium with imipramine or reserpine.

The adaptability of the cyclic AMP phosphodiesterase (PDE) following chronic treatment (4-6 weeks) with lithium, reserpine, imipramine, and combinations of lithium with imipramine or reserpine has been studied in rat brain tissue. All drugs, except lithium, were given intraperitoneally once a day. Control animals received only vehicle. Lithium was given in the diet in a concentration yielding a plasma level of 0.5-0.6 mmol/l. The PDE activity was measured in homogenates from cerebral cortex and "limbic" forebrain. These two brain areas were both found to contain three types of PDE activity. One was mainly associated with the pellet after a 10,000 X g centrifugation for 10 min. This enzyme hydrolyzed both cyclic AMP and cyclic GMP with a Km value of 130 +/- 48 microM for cyclic AMP, but was insensitive to calcium and calmodulin. Two types were mainly found in the supernatant after the centrifugation with Km values cyclic AMP of 300 +/- 108 microM and 4 +/- 3 microM, respectively. The former hydrolyzed both cyclic AMP and cyclic GMP and was stimulated 7-fold by calcium and calmodulin, while the latter only hydrolyzed cyclic AMP and was insensitive to calcium and calmodulin. None of the treatments affected the "pellet" enzyme or the low affinity enzyme from the supernatant. However, lithium treatment, even combined with reserpine or imipramine, increased the high affinity enzyme. This increase was also apparent in the DEAE-ion exchange chromatographic profile of the PDE enzymes.

Allergic reactions, cyclic AMP and histamine release.

Both isobutylmethylxanthine and theophylline increased the level cyclic AMP in the mast cell. Theophylline reduced the allergic histamine release, whereas isobutylmethylxynthine caused a pronounced potentiation of the histamine release. This indicates that the hypothesis of an inverse relationship between the level of cyclic AMP in mast cells and histamine release is too simple.

Cyclic AMP and allergic histamine release. Influence of methylxanthines on rat mast cells.

Both isobutylmethylxanthine and theophylline increased the level of cyclic AMP in rat mast cells. Theophylline reduced the allergic histamine release, whereas isobutylmethylxanthine caused a pronounced potentiation of the histamine release. This indicates that the hypothesis of an inverse relationship between the level of cyclic AMP in mast cells and histamine release is inadequate.

A simple and inexpensive protein binding assay for cyclic AMP in biological materials.

We have developed a simple and inexpensive method for largecapacity cAMP determination in biological materials. The assay is based on competitive binding of 3H-cAMP to proteins isolated from rabbit skeletal muscle. Bovine serum albumin is added to the incubate to reduce non-specific interference. Separation of free and bound radioactivity is performed by (NH4)2SO4 precipitation allowing determination of either free or bound fraction. In the latter case, all procedures are performed in the same tube, to which is finally added 1.2 ml of scintillation fluid for counting. By this only one fourth. The method has been applied to rat tissue extracts and urine with satisfactory sensitivity, precision and accuracy.

Forskolin-stimulated adenylate cyclase activity in rat cerebral cortex following chronic treatment with psychotropic drugs.

Rats were treated with lithium, imipramine, reserpine, and lithium combined with imipramine or reserpine. Lithium was given in the diet (40 mmol/kg) resulting in a serum-Li+ level of 0.5-0.6 mmol/l. Other drugs were dissolved in 0.9% saline and given intraperitoneally once or twice daily. After 3 weeks of treatment, forskolin-stimulated adenylate cyclase activity was measured in cerebral cortex homogenates. Reserpine did not affect the forskolin stimulation, while both imipramine and lithium caused a decrease in this activity. The combined treatments lithium-imipramine and lithium-reserpine also exhibited a clear decrease in forskolin stimulation, but the effect of concomitant lithium and imipramine treatment did not differ from the effect seen after any of the treatments alone. The unstimulated activity was unaltered by all treatments. The inhibition of lithium and imipramine on the forskolin stimulation indicates an interference of these two drugs with the forskolin-mediated activation of the adenylate cyclase.

No change in rat cerebral cortex calmodulin content following chronic treatment with lithium, reserpine, imipramine, and lithium combined with reserpine or imipramine.

Rats were treated 2-3 weeks with lithium, reserpine, imipramine, and combinations of lithium with reserpine or imipramine. Lithium was given in the diet, while the other drugs were dissolved in 0.9% saline and given intraperitoneally twice daily. The control and lithium groups received only vehicle injections. Twenty-four hours after the last injection the rats were decapitated and the cerebral cortex dissected. The tissue was sliced and the noradrenaline-stimulated cyclic AMP accumulation determined or the tissue was homogenized and centrifuged at 10,000 X g for 30 min. and the calmodulin content determined in the pellet and the supernatant. Reserpine treatment was found to cause an 50% increase in the noradrenaline-stimulated cyclic AMP accumulation, while treatment with imipramine and the combination lithium-imipramine decreased the noradrenaline-stimulated cyclic AMP accumulation by 40%. The tissue content of calmodulin was, however, found unaltered by all treatments.

Characterization of the beta-adrenergic receptor on the human platelet: a beta 2-subtype.

The human platelet beta-adrenergic receptor was characterized by using the ability of different drugs to stimulate the adenylate cyclase activity and the effects of various beta-antagonists to block the isoprenaline-stimulated adenylate cyclase activity. Isoprenaline was found 10 times more potent than adrenaline and 1000 times more potent than noradrenaline in stimulating the adenylate cyclase activity in these cells. Isoprenaline-stimulated activity was blocked by the non-selective beta-antagonists propranolol and alprenolol and by the beta 2-selective antagonist IPS 339 and prenalterol. Metoprolol, a beta 1-selective blocker, was without effect on the isoprenaline-stimulated adenylate cyclase activity. We conclude from our findings that the beta-adrenergic receptor type on the human platelet is mainly of the beta 2-subtype.