A dermatologist from our hospital prescribes the following: erythromycin 2% in Cetomacrogol cream AD 100 g buffing with borate buffer up to pH 8.6.

Erythromycine has its greatest stability at a pH around 8. The buffered Cetomacrogol Cream has a pH 5 and cannot be used for an erythromycin cream (see TMF). I would base myself on the hydrophilic cream with erythromycin and metronidasole from the TMF (see question: metronidazole 500mg, erythromycin 2g, O/W cream ad 50g. How is this cream best prepared?) and prepare it with omit metronidazole. The pH can optionally be checked with a pH strip.