[On the dropping behaviour of drug solutions (author's transl)]

On testing a preferentially inserted dropping device (marginal-dispensing dropper) of high-pressure process-polyethylene, the authors stated irregular dropping which impaired the dosing of ethanolic-aqueous drug solutions. The addition of macromolecular viscosity-increasing agents (0.2 or 0.3% of hydroxyethylcellulose and 0.5% of methyl cellulose being very suited) permitted to obtain a sequence of uniform easy-to-count drops and to reduce the amount of variation in the individual drop masses. Manufacturing differences among the dropping devices are a substantial source of error which might be reduced by fully automatic control. An improvement in the dropping behaviour of the dropping device under investigation can be expected from suggestions for changes in its design. The use of a "general purpose dropping device" is inconsistent with the specific properties of the drug preparations. Dosing accuracy is higher with central-dispensing droppers than with marginal-dispensing ones.