1. The effects of polyethylene glycol (PEG) 200 administered by gavage on electrolyte and water excretion were investigated in the rat.
2. PEG 200 led, in intact rats, to dose-related increased drinking and to diuresis.
3. In the first 2 h after PEG 200 administration, water consumption in intact rats exceeded urine output.
4. PEG 200 enhanced the excretion of both sodium and potassium, but the sodium excretion was proportionately greater, resulting in an elevation of the urinary sodium/potassium ratio.
5. Bilateral nephrectomy was not accompanied by increased drinking in PEG 200-treated rats, although raised serum osmolality was seen.
6. Thus, given by gavage, PEG 200 is not an inert vehicle for drug administration.