An oral trimethylamine challenge test has been used to confirm the heterozygous status of patients with 'fish-odour syndrome'. By measuring the percentage of total urinary trimethylamine-related material excreted as the N-oxide, no discrimination could be made between obligate heterozygotes (parents of 'fish-odour syndrome' patients) (n = 15; 96 +/- 2%, range 92-98%) and control individuals (parents of unaffected children) (n = 16; 96 +/- 2%, range 93-99%) on a normal diet. However, after ingesting a trimethylamine load (600 mg base) the obligate heterozygotes were clearly distinguishable (76 +/- 3%, range 71-79%) from controls (95 +/- 2%, range 91-99%) (t-test; p <0.001). One of a hundred apparently normal volunteers who were subsequently challenged with trimethylamine had a N-oxidation capacity which fell within the range found among the obligate heterozygotes.

1. Dipropyl [35S]-sulphone was administered by gavage (4.24 mmol/4 ml/kg body weight) to the adult male Wistar rat following an overnight fast. 2. Urine was the major route of excretion (83%) with more radioactivity appearing during the second day (47%) than the first (28%). Only small amounts were found in the faeces (10%). Biliary excretion played an important role with substantial amounts of the dose (33%) passing through the bile duct during 0-48 h. A near total recovery was achieved suggesting that only small amounts (2%) may have been lost as volatile components. 3. Metabolism was limited, the majority (> or = 98%) of the sulphone being recovered unchanged. Oxidation of the sulphur with the formation of inorganic sulphate was the only pathway observed.

1. The fate of [14C]-dimethylamine was investigated following oral administration to four male volunteers. 2. The major route of excretion was urine, with 94% of the administered radioactivity being voided over 3 days (87% during the first 24 h). Small amounts (1-3%) of radioactivity were found in the faeces and expired air. 3. Metabolism was limited with only 5% being demethylated to methylamine. The remainder of the dose was excreted unchanged. 4. Pharmacokinetic studies indicated rapid (t1/2ab = 8 min) and extensive absorption (bioavailability = 82%) from the gastrointestinal tract followed by widespread distribution and a fairly prompt excretion (t1/2el = 6-7 h) with a plasma clearance of 190 ml/min.

1. [U-14C]-dimethylamine hydrochloride was administered by gavage (20 mumol/kg body weight) to adult male Wistar rat and CD1 strain mouse. 2. In both species, urine was the main route of excretion with the majority of radiolabel (91%) being voided during the first day. Additional small amounts of radioactivity were detected in the 24-72 h urine (2%), in faeces (2%) and amidst exhaled air (1%), with minor amounts remaining within the carcass (1%) after 3 days. 3. Metabolism was limited to demethylation, with the majority of the compound (89% dose; 96% urinary radioactivity) being excreted unchanged.