Genito-urinary

Question 1

What drugs reduce the effect of oral contraceptives?

Answer 1

• enzyme inducing drugs
• anti-epileptics: carbamazepine or phenytoin
• antibiotics: rifampicin and rifabutin
• natural produces: St. John’s wort
• they all increase the production of hepatic CYP450

Question 2

Why prescribe HRT?

Answer 2

• to treat symptoms of hot flushes/sweats, dyspareunia and osteoporosis
• NOT for heart disease
• examples: estradiol, Premarin, medroxygprogesterone acetate, norethisterone, levonorgestrel
• given oral, transdermal, implant, trans vaginal, nasal
• risk: venous thromboembolism, CVS disease, stroke

Question 3

Mifepristone (RU486)

Answer 3

• progesterone receptor antagonist
• acts as anti-progesterone
• used for pregnancy termination
• prevents myometrium contractions

Question 4

Clomiphene

Answer 4

• SERMS
• used for anovulation
• competes wth oestrogen for ER binding
• leads to ovulation production through increased production of anterior pituitary hormones

Question 5

Tamoxifen

Answer 5

• pro-drug
• little affinity for estrogen receptor
• metabolised in liver to active derivatives
• varies for each woman because isoenzyme
• active metablites competes with oestrogen binding to ER
• SERM
• in endometrium it is an ER agonist
• in breast it is an ER antagonist
• binding of the ER following tamoxifen treatment causes cells to arrest the cell cycle

Question 6

Ulipristal aceatate

Answer 6

• SPRM
• used for emergency contraception by delaying ovulation
• prevents LH surge
• also effective for the treatment of uterine fibroids
• has different effects dependent on the tissue