- The relationship between phenazone (antipyrine) metabolite formation and theophylline metabolism in healthy and frail elderly women. Groen, K., Horan, M.A., Roberts, N.A., Gulati, R.S., Miljkovic, B., Jansen, E.J., Paramsothy, V., Breimer, D.D., van Bezooijen, C.F. Clinical pharmacokinetics. (1993)