Original paper
Changes in the dynamics of hair growth in rats after application of methotrexate, metoprolol and naproxen

Aim: The aim of this study was to assess the dynamics of hair regrowth in rats after application of methotrexate, metoprolol and naproxen in comparison with cyclophosphamide.
Material and methods: On the first day of the study, all 70 rats underwent manual epilation. The epilation was repeated every month, alternatively on symmetric sides of the back. The hair roots were sampled twice a week and were examined in a light microscope.
Results: In the group which received cyclophosphamide, it was visible that the course of all the cycles presents a pattern of telogen-dystrophic alopecia. Macroscopic signs of diffused depletion of hair are observed. In the group which received methotrexate telogen-dystrophic alopecia is also observed. Metoprolol initially shortens the hair cycle and next the hair cycle returns to normal. On the macroscopic examination one can see a positive effect of the drug (i.e. increased hair density and volume). Naproxen initially leads to shortening of the hair cycle and then it gradually induces a kind of “tolerance”. This results in normal hair length of the following hair cycles.