Neurologic, psychiatric, and other medical manifestations of nitrous oxide abuse: A systematic review of the case literature.

BACKGROUND/OBJECTIVES: Nitrous oxide (N2 O) is known to have abuse potential, although debate regarding the toxic effects of such abuse continues. Our objective was to review the case literature and present the neurologic, psychiatric and medical consequences of N2 O abuse. METHODS: A systematic literature review was completed for case reports using keywords "nitrous oxide" with "abuse/abusing" or "misuse/misusing" or "overuse/overusing" or "addiction." Non-English-language cases and cases not involving direct toxic effects of N2 O were excluded as were commentaries or personal essays. Clinical presentation, frequency of N2 O abuse, laboratory studies, imaging, ancillary tests, treatments and outcomes were collected from case reports. RESULTS: Our review returned 335 Pubmed, 204 Web of Science, 73 PsycINFO, 6 CINAHL, 55 EMBASE and 0 Grey Literature results, and after exclusion and removal of duplicates, 91 individual cases across 77 publications were included. There were also 11 publications reporting 29 cases of death related to N2 O abuse. The majority of cases (N = 72) reported neurologic sequelae including myeloneuropathy and subacute combined degeneration, commonly (N = 39) with neuroimaging changes. Psychiatric (N = 11) effects included psychosis while other medical effects (N = 8) included pneumomediastinum and frostbite. Across all cases N2 O abuse was correlated with low or low-normal Vitamin B12 (cyanocobalamin) levels (N = 52) and occasionally elevated homocysteine and methylmalonic acid. CONCLUSIONS/SCIENTIFIC SIGNIFICANCE: N2 O abuse represents a significant problem because of the difficulty involved with identification and the toxicity related to chronic abuse including possible death. Health professionals should be aware of the toxic effects of N2 O and be able to identify potential N2 O abuse. (Am J Addict 2016;25:358-369).

Bupropion treatment for cocaine abuse and adult attention-deficit/hyperactivity disorder.

There are few published studies assessing the efficacy of pharmacologic treatments for attention-deficit hyperactivity disorder (ADHD) among substance abusers seeking treatment. Eleven patients who met DSM-IV diagnostic criteria for cocaine dependence and adult ADHD were entered into a 12-week single-blind trial of divided daily doses of bupropion (BPR). All patients received weekly individual standardized relapse prevention therapy. Treatment compliance and retention were good. Patients reported significant reductions in attention difficulties, hyperactivity and impulsivity. Self-reported cocaine use, cocaine craving, and cocaine positive toxicologies, also decreased significantly. In a previously published trial, 12 patients who met similar diagnostic criteria for adult ADHD and cocaine dependence were entered into a 12-week trial of divided daily doses of sustained-release methylphenidate (MPH). Improvements observed on BPR were similar to, and did not differ from those previously observed with MPH. These preliminary data suggest that BPR may be as effective as sustained-release MPH, when combined with relapse prevention therapy, for cocaine abusers with adult ADHD. However, a future study directly comparing BPR to MPH in a double-blind placebo-controlled trial is needed.