Letrozole Anti E ?????

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Whan using Letro is there a need to use Proviron or Nolvadex?

[Iwan2bsolid2]

check this out

Nolvadex (tamoxifin) and Letrozole.

Pharmacokinetic interactions

The combination of an aromatase inhibitor with tamoxifen is a possible route whereby improved efficacy of endrocrine therapy might be achieved. The consideration of such clinical combinations requires assessment of potential pharmacokinetic interactions. This was stressed by the study of Lien et al. (1990), who demonstrated that combination with AG led to decreases in tamoxifen concentrations of about 70%. We have now performed an analogous study with anastrozole, and found that this inhibitor does not lead to decreased tamoxifen concentrations (Dowsett et al. 1999b). In this issue of Endocrine-Related Cancer, Ingle et al. (1999) also report that letrozole has no impact on tamoxifen concentrations. Thus these two compounds may be added to tamoxifen
with no concern that the pharmacokinetics of the antioestrogen will be compromised. However, unexpectedly, we have noted that, conversely, in combination with tamoxifen, the plasma concentrations of letrozole are reduced by between 35 and 40% (Dowsett et al. 1997). The mechanism underlying this highly unexpected finding is at present unknown. No other drugs are known to interact with tamoxifen in this manner, but it is of concern that systematic pharmacokinetic interaction studies with tamoxifen have been relatively limited, despite the millions of women years of its usage. Decreases in AG concentration did not occur when it was combined with tamoxifen. The question of whether the anastrozole-tamoxifen combination will demonstrate this difference is currently under study. As a result of this pharmacokinetic interaction, the plasma concentrations of letrozole are equivalent to those predicted to be achieved by 1.5-2.0 mg/day when given alone. It is possible that this may be of clinical importance because, as mentioned above, there is a dose-response relationship between letrozole 0.5 mg/day and 2.5 mg/day (Dombernowsky et al. 1998, Gershanovich et al. 1998). Thus, with the combination, the complete additive efficacy of letrozole may not be achieved.