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MAO Inhibitors: Predicting Response/Maximizing Efficacy
Published in Mark S. Gold, R. Bruce Lydiard, John S. Carman, Advances in Psychopharmacology: Predicting and Improving Treatment Response, 2018
Most clinical experience with MAOI suggests an incidence of inducing manic or hypomanic episodes similar to that seen with TCA. In approximately 10% to 15% of patients with depression and in 35 to 60% of patients with bipolar illness, either antidepressant can precipitate a switch to mania.48,49 Recently it has been suggested by Potter et al.50 that low doses of clorgyline, a selection MAOA inhibitor, have beneficial effects on previously intractable bipolar illness. It was used alone or in combination with lithium. Similarly Quitkin et al.51 and Himmelhoch et al.52 report successful treatment of a number of bipolar depressed patients that had been resistant to TCA, with usual therapeutic doses of phenelzine or relatively low doses of tranylcypromine. Himmelhoch et al.52 report nearly 20% induced paranoid/manic state. At this time we would suggest cautious use of either TCA or MAOI in bipolar depression that is resistant to lithium alone. The antidepressant should be added to the lithium, relatively lower doses should be tried first, and it should be tapered as soon as mood improvement occurs. It should also be noted that induction of mania or rapid cycling can occur, even after the MAOI has been discontinued.
ENTRIES A–Z
Published in Philip Winn, Dictionary of Biological Psychology, 2003
MONOAMINE OXIDASE is an ENZYME that catalyses the destruction of many types of MONOAMINE: monoamine oxidase inhibitors (MAOIs) are a class of DRUG that prevent this action, in general therefore promoting an increase in levels of monoamines. The earliest example was IPRONIAZID (one of the hydrazine group of monoamine oxidase inhibitors): later examples include PHENELZINE and NIALAMIDE (hydrazines), and PARGYLINE and TRANYLCYPROMINE (non-hydrazines), CLORGYLINE and DEPRENYL. The early monoamine oxidase inhibitors, hydrazines and non-hydrazines alike, were non-selective (that is, they acted on monoamine oxidase- A and -B equally well). Clorgyline and deprenyl are modern monoamine oxidase inhibitors, selective for MAO-A and MAO-B respectively. Monoamine oxidase inhibitors have a variety of uses: they can be given experimentally as broad spectrum enhancers of monoamine activity; and pargyline is typically given in conjunction with the catecholamine selective neurotoxin 6-HYDROXYDOPAMINE to incrcase its effectiveness. More importantly, monoamine oxidase inhibitors have been used in the treatment of DEPRESSION (iproniazid was one of the first ANTIDEPRESSANT drugs used—later drugs such as the TRICYCLICS however have largely replaced monoamine oxidase inhibitors) while deprenyl has been used in the management of PARKINSON'S DISEASE. Interestingly, deprenyl, like some of the other monoamine oxidase inhibitors, is metabolized to methamphetamine and AMPHETAMINE. After treatment with deprenyl for three days or more, detectable amounts of these can be found in the urine.
Monoamine oxidase A inhibition by toxic concentrations of metaxalone
Published in Clinical Toxicology, 2020
Brett Cherrington, Ulrich Englich, Supa Niruntari, William Grant, Michael Hodgman
Metaxalone, clorgyline, and recombinant human MAO-A were purchased from Sigma-Aldrich, St. Louis, MO, USA. MAO-Glo® V1401 Assay System was obtained from Promega Corporation (Madison, WI, USA). Clorgyline is a potent, selective, and irreversible inhibitor of MAO-A [14]. Briefly, the test compound is incubated with a proprietary MAO substrate and MAO-A. MAO-A will liberate methyl ester luciferin from MAO substrate. After 1 h of incubation, an esterase and luciferase are added to the reaction well, resulting in luminescence. Luminescence is proportional to the MAO-A activity of the solution. If MAO inhibition by the test compound occurs there is a proportional decrease in the amount of luminescence [15]. Luminescence was measured with a Biotek Synergy HT microplate reader. All experiments were run between 25.7 and 27.1 °C. Per the manufacturer of MAO-Glo® Assay System MAO-A reactions can be run at room temperature [15]. Luminescence was measured at various time points after adding luciferase. Each microplate included positive and negative controls (reaction wells without test compound and without MAO substrate respectively) to establish maximum and minimum luminescence for that particular experiment.
Design, synthesis, and evaluation of 1, 4-benzodioxan-substituted chalcones as selective and reversible inhibitors of human monoamine oxidase B
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2020
Zhuo Kong, Demeng Sun, Yanmei Jiang, Yun Hu
The inhibitory effects of 28 chalcone derivatives on human MAO-B and MAO-A enzymes were screened using a fluorescence-based assay. The tested concentration was 1 µM unless otherwise stated. Irreversible inhibitors R-(–)-deprenyl and rasagiline were used as positive controls for MAO-B inhibition at 0.1 µM. Clorgyline was used as a positive control for MAO-A inhibition. The results are summarised in Table 1.
Blocking oestradiol synthesis pathways with potent and selective coumarin derivatives
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2018
Sanna Niinivehmas, Pekka A. Postila, Sanna Rauhamäki, Elangovan Manivannan, Sami Kortet, Mira Ahinko, Pasi Huuskonen, Niina Nyberg, Pasi Koskimies, Sakari Lätti, Elina Multamäki, Risto O. Juvonen, Hannu Raunio, Markku Pasanen, Juhani Huuskonen, Olli T. Pentikäinen
The protein in addition to the reagents for the chromogenic solution (vanillic acid (4-hydroxy-3-methoxylbenzoic acid, 97% purity), 4-aminoantipyrine (reagent grade), horseradish peroxidase, and the substrate tyramine hydrochloride (minimum 99% purity)) as well as the potassium phosphate buffering agents (potassium phosphate dibasic trihydrate (≥99% ReagentPlusTM) and potassium phosphate monobasic (minimum 98% purity, molecular biology tested)) were all purchased from Sigma-Aldrich (St. Louis, MO). The protocol of continuous spectrophotometric assay by Holt et al. was first used to determine the activity of the proteins23. The assay was performed in 0.2 M potassium phosphate buffer pH 7.6 on 94-well plates (NuncTM 96 F microwell plate without a lid, Nunc A/S, Roskilde, DK) with chromogenic solution containing 250 µM vanillic acid, 125 µM 4-aminoantipyrine and 2 U/ml horseradish peroxide in the total assay volume of 200 µl. The protein was first incubated for 30 min at 37 °C in the chromogenic solution and then the substrate tyramine was introduced at 0.5 mM final plate concentration completing the assay volume. The activity measurement using multilabel reader (VictorTM X4, 2030 Multilabel Reader, PerkinElmer, Waltham, MA) at A490 immediately followed and the plates were read 300 times every 15 s using 1 s exposure time. The assay should produce absorbance change of ∼0.3523. The more active MAO-A produced over 0.5 change in absorbance reaching the assay maximum in 30 min with 25 µg of protein (enzymatic activity 5.25 units) per well while MAO-B produced the expected 0.35 change in absorbance with 50 µg of protein (enzymatic activity 3.2 units) per well and reached the assay maximum in 2 h. These protein concentrations were selected to be used to analyse the molecules 1–9. The analysis conditions followed the above-described assay protocol23 and the activity of tested molecules was measured at 100 µM for MAO-A and at 10 µM for MAO-B. The analysis was performed as single point measurements and the signal was read by the same instrument at the expected assay maximum indicated by the activity measurements, at 30 min for MAO-A and at 2 h for MAO-B, respectively. Clorgyline was used as MAO-A and pargyline as MAO-B inhibitor control. Both of the control inhibitors provided 100% inhibition at the assay concentration of the test molecules. In addition, pIC50 values were determined for MAO-B inhibition using duplicated dilution series and the pIC50 value calculated for MAO-B inhibition by pargyline was 6.21. The observed activity was calculated as inhibition percentage (Table 1). The pIC50 values were calculated with GraphPad Prism version 5.03 (GraphPad Software Inc., San Diego, CA).