5.2.2 Oral Contraceptives Flashcards
What enzymes metabolise COCP and POP?
CYP450 in liver
What can affect COCP and POP contraceptives?
Efficacy is affected by enzyme inducing drugs which stimulate CYP450, therefore more breakdown of contraceptives
What drugs cannot be taken at the same time as COCP and POP?
Anti-epileptics
Carbamazepine or phenytoin
Antibiotics
Rifampicin and rifabutin
St John’s Wort
All increase production of CYP450
What natural products can enhance oestrogen absorption?
Soya protein
Enhances oestrogen absorption and reduces its storage in adipose and muscle
Half life reduced from 15 hours to 7 hours
What is the combined oral contraceptive pill (COCP)?
Pill containing synthetic oestrogen and progesterone
How long is the COCP taken for?
21 days with a 7 day break
What does the COCP do?
Prevents ovulation
Reduces endometrial receptiveness to implantation
Thickens cervical mucus
What are the adverse effects of the COCP?
Increased risk of:
- VTE
- Stroke
- Breast cancer
- Cervical cancer
What are the contraindications of the COCP?
- Smoker
- Previous VTE
- High BMI
- Hypertension
- IHD/stroke
- Migraine
- Breast cancer
- Cirrhosis
Basically, things that put you at higher risk of clots, more oestrogen so breast cancer, cirrhosis as impaired oestrogen break down
What does the progestogen-only pill do?
Thickens cervical mucus
Reduced cilia activity in fallopian tubes
OVULATION IS NOT PREVENTED
Contains low-dose progestogen, taken daily with NO breaks
What are the advantages of the POP?
99% reliability
Can be used if COCP cannot
What are the disadvantages of the COCP?
No STI protection
Strict timing- user dependant
Menstrual irregularities
Increased risk of ectopic pregnancy (due to immotile cilia)
When is hormone replacement therapy offered?
Vasomotor or mood disorders
Urogenital symptoms
How is HRT given?
Oral or transdermal
Combined oestrogen and progesterone if woman has a uterus
Oestrogen alone if there is no uterus
Progesterone protects the endometrium from hyperplasia
What is the first line treatment for urogenital symptoms?
Low-dose vaginal oestrogen
What types of oestrogens are used in HRT?
Natural oestrogens
e.g. oestradiol
What types of progesterones are used in HRT?
Progesterone analogues
Testosterone analogues
Bioidentical- less side effects and risks
What are the risks of using HRT?
Endometrial cancer (if oestrogen is unopposed)
Breast cancer
VTE- oral only
Stroke- oral only
CHD- if before 60
Explain how HRT increases the risk of VTE
Increased:
- Activated protein C resistance
- Thrombin activation
Decreased:
- Anti-thrombin III activity
- Protein S levels
- Factor VII levels
- Tissue factor pathway inhibitor
What is used to treat osteoporosis?
Bisphosphonates
How do bisphophonates work?
Reduce bone turnover by controlling osteoclast activity
When are bisphophonates used?
Prophylaxis and treatment of osteoporosis
Management of other diseases involving bone e.g. Paget’s disease of bone, malignancy
Identify the pharmacokinetics of bisphophonates
Long half life
Poor gut absorption
Absorption affected by food, needs to be taken on an empty stomach
What adverse reactions can occur when taking bisphophonates?
Upper GI effects
Oesophagitis- remain seated of standing for 30 minutes after taking
Hypocalcaemia
Check calcium and vitamin D levels prior to treatment
What is Mifepristone?
Progesterone and glucocorticoid receptor antagonist
What does Mifepristone do?
Acts as an anti-progesterone
Sensitises myometrium to prostaglandin-induced contractions
When is mifepristone used?
Used for pregnancy termination and medical management of miscarriage
What do Selective Oestrogen Receptor Modulators (SERMs) do?
Interacts with oestrogen receptors as agonists or antagonists depending on the target tissue
What are some very important Selective Oestrogen Receptor Modulator examples?
Tamoxifen- Breast cancer
Raloxifene- Prevention of osteoporosis in menopause and breast cancer
Where is tamoxifen metabolised?
Liver to active metabolites
Active metabolites compete with oestrogen
What tissues does tamoxifen target?
Breast tissue
Bone
Hypothalamus
Endometrium
Explain the action of tamoxifen in breast tissue
Antagonistically competes with oestrogen for binding sites
Causes antioestrogenic and antitumour effects
Slows cell cycling
Explain action of tamoxifen in bone
Stimulates oestrogen receptors instead of blocking them
Exerts oestrogenic agonist effect, prevents osteoporosis in post-menopausal women
What is the action of tamoxifen on the hypothalamus?
Oesotrogen agonist
Increases gonadotropin levels and can induce ovulation
How does tamoxifen act on the endometrium?
Oestrogen agonist
Can lead to endometrial hyperplasia
What is clomiphene?
Non-steroidal ovulatory stimulatory
Acts as a selective oestrogen receptor modulator (SERM)
When is clomiphene used?
Treatment of anovulation
How does clomiphene work?
Competes with oestrogen for receptor binding
Leads to ovulation induction through increased production of LH and FSH
What is an example of a selective progesterone receptor modulator (SPRMS)?
Ulipristal acetate (Ella one)
How does ulipristal acetate (Ella one) work?
High-affinity binding to progesterone receptors
Can be agonist or antagonist
When is Ellaone (ulipristal acetate) used?
Emergency contraception
Inhibits or delays ovulation via suppression of the LH surge
