Hormone receptor inhibitors

Hormones and hormone receptor inhibitors can be administered because some tumors have hormone receptors. The response of the tumor to such therapy, however, is difficult to predict. It can be detrimental or beneficial depending on the hormone, the type of cancer, and even the individual. These drugs are used routinely to treat breast cancer patients with receptor-positive tnmor types. 

Van Beeren HC, Jong WMC, Kaptein E et al (2003) Dronedarone acts as a selective inhibitor of 3,5,3 -triiodothyronine binding to thyroid hormone receptor-a. in vitro and in vivo evidence. Endocrinology 144 552-558... 

Winer EP, Hudis C, Burstein HJ, et al. American Society of Clinical Oncology technology assessment on the use of aromatase inhibitors as adjuvant therapy for postmenopausal women with hormone receptor-positive breast cancer Status report 2004. J Clin Oncol 2005 23 619-629. 

Almost all diuretics exert their action at the luminal surface of the renal tubule cells. Their mechanism of action includes interaction with specific membrane transport proteins like thiazides, furosemide etc., osmotic effects which prevent the water permeable segments of the nephron from absorbing water like mannitol, and specific interaction with enzyme like carbonic anhydrase inhibitors i.e. acetazolamide, and hormone receptors in renal epithelial cells like spironolactone. 

Complementary structures of biological materials, especially those of proteins, often result in specific recognitions and various types of biological affinity. These include many pairs of substances, such as enzyme-inhibitor, enzyme-substrate (analog), enzyme-coenzyme, hormone-receptor, and antigen-antibody, as summarized in Table 11.2. Thus, bioaffinity represents a useful approach to separating specific biological materials. 

Anasfrozole (Arimidex) [Anrineoplasric/Nonsteroidal Aromatase Inhibitor] Uses Breast CA postmenopausal w/ met breast CA, adjuvant Rx postmenopausal early hormone-receptor(+) breast CA Action Selective nonsteroidal aromatase inhibitor, X circ estradiol Dose 1 mg/d Caution [D, ] Contra PRG Disp Tabs SE D, HTN, flushing, T bone/tumor pain, HA, somnolence Interactions None noted EMS May cause vag bleeding during 1st few wks of Tx OD May cause N/V, abd discomfort, and bloody stools symptomatic and supportive... 

Tamoxifen versus aromatase inhibitors While tamoxifen is still widely regarded as the standard adjuvant endocrine treatment for postmenopausal women with localized breast cancer, provided it is hormone receptor positive, there are problems with recurrence and adverse effects. Reservations have recently been expressed about the future place of tamoxifen, and the case has been made that it is time to move from tamoxifen to the oral aromatase inhibitors (19). 

This study has again confirmed that endometrial problems can be induced by tamoxifen early in the course of treatment and that these problems do not arise with aromatase inhibitors, which may actually reduce the endometrial changes induced by tamoxifen. The idea that the new oral aromatase inhibitors might well replace tamoxifen in breast cancer was tentatively advanced in SEDA-26 (p. 445) and has now been supported by some of the material cited above, as well as by a panel consensus (25). Citing efficacy and safety data on anastrozole, exemestane, and letrozole, the authors concluded that third-generation aromatase inhibitors may be considered first-line therapy of hormone-receptor-positive advanced breast cancer in postmenopausal women and may also be used for preoperative therapy of breast cancer. 

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