Teniloxazine

Teniloxazine belongs to the same small morpholine chemotype as viloxazine; its full structure is 2-{[2-(thiophen-2-ylmethyl)phenoxy]methyl}morpholine, formula C16H19NO2S, and it was handled clinically as the maleate salt. It was numbered Y-8894 during development at Yoshitomi Pharmaceutical Industries in Japan, and appears in the older literature under the generic names sufoxazine and sulfoxazine before teniloxazine became the settled international nonproprietary name.

The defining pharmacology is norepinephrine reuptake inhibition. In mouse cerebral synaptosomes it blocked norepinephrine uptake roughly 800 times more potently than dopamine uptake and about 1250 times more potently than serotonin uptake, and in vivo it lowered the noradrenaline metabolite MHPG while raising the serotonin metabolite 5-HIAA ^[1]. That profile places it as a fairly selective noradrenaline reuptake inhibitor rather than a true dual serotonin-norepinephrine agent, with a secondary 5-HT2A antagonist action layered on top.

Most of the preclinical program framed the drug as an anti-amnesic and anti-anoxic cerebral agent rather than a classical antidepressant. Sufoxazine reversed experimental amnesia induced by carbon dioxide exposure, electroconvulsive shock and scopolamine in mice ^[4], reduced coma duration and improved survival under potassium cyanide and hypoxic challenge ^[5], preserved brain ATP, phosphocreatine and energy charge during cyanide-induced anoxia ^[6], normalized the abnormal electrocorticogram produced by internal capsule lesions ^[7], and improved memory deficits after transient cerebral ischemia in rats ^[8]. It also facilitated learning in the radial maze, outperforming dihydroergotoxine and calcium hopantenate in that assay ^[9].

Human data are limited and old. A double-blind crossover study in healthy young and elderly men found that a single 50 mg dose lacked the anticholinergic, sedative and cardiovascular effects seen with nortriptyline in young subjects, though in the elderly it raised pulse rate, lowered systolic blood pressure and reduced salivary flow ^[2]. A comparison of nine antidepressants on physiological parameters in volunteers included Y-8894 at 50 mg and grouped it among the better-tolerated agents on flicker fusion, body sway and salivation ^[11]. Quantitative pharmaco-EEG work classed it with the nootropics, reporting an increase in alpha activity of the kind associated with that drug category ^[10].

Pharmacokinetics were characterized in a single comparative study: at 80 mg of the maleate every twelve hours, healthy volunteers showed oral clearance around 14.6 to 18.0 ml/min/kg and a half-life that shortened from about 6.2 to 4.8 hours over a week of dosing, consistent with autoinduction of its own metabolism, while cirrhotic patients had roughly halved clearance, a more than doubled half-life and about two-fold accumulation ^[3]. That hepatic sensitivity is the clearest practical caution in the record.

Teniloxazine is now largely a historical and reference-list entry. It survives mainly as a name in review taxonomies of norepinephrine reuptake inhibitors and newer-generation antidepressants ^[12][13] and in analytical-chemistry method reviews ^[14], where it is grouped with atomoxetine, reboxetine and viloxazine as a noradrenergic agent with limited activity at other sites. It never achieved a presence outside Japan and carries no ATC code.

Human safety data are sparse and dated. In single-dose volunteer studies 50 mg was well tolerated and, unlike nortriptyline, produced no meaningful anticholinergic, sedative or cardiovascular effects in young subjects; in elderly volunteers the same dose raised pulse rate, lowered systolic blood pressure and reduced salivary flow, changes attributed partly to altered pharmacokinetics with age ^[2]. Because oral clearance is roughly halved and the half-life more than doubled in hepatic cirrhosis, with about two-fold accumulation on repeated dosing, lower maintenance doses are advised in liver dysfunction ^[3]. Long-term safety, overdose behavior, use in pregnancy, abuse potential and comprehensive drug-interaction data are essentially absent from the accessible English literature, so its risk profile beyond these narrow studies is genuinely unknown.

Teniloxazine was developed by Yoshitomi Pharmaceutical Industries in Japan and studied under the code Y-8894 and the early names sufoxazine and sulfoxazine. The preclinical series published between 1985 and 1988 in Folia Pharmacologica Japonica framed it as a cerebral activator for cerebrovascular insufficiency, testing it in models of experimental amnesia, cerebral anoxia and ischemia ^{[4][5][6][7][8]}. Clinical pharmacology in healthy volunteers followed in the mid-to-late 1980s ^[2][11], and pharmacokinetics were characterized into the 1990s ^[3]. It was ultimately marketed in Japan as an antidepressant under the brand names Lucelan and Metatone. It was never approved outside Japan, has no assigned ATC code, and by the 2010s appeared chiefly as a reference entry in reviews of norepinephrine reuptake inhibitors ^[12][13][14].

Teniloxazine is obscure. It is not a familiar name even among people who follow noradrenergic antidepressants and cerebral activators, and it has no meaningful following in the nootropics community; it is not sold as a supplement or research chemical in any notable way. Where it appears at all is in academic taxonomies that list it alongside viloxazine, reboxetine and atomoxetine as a selective noradrenaline reuptake inhibitor with minor secondary activity ^[12][14]. Its reputation, such as it is, rests on the mid-1980s Japanese studies rather than any sustained modern use.