Pharmacology 3: Sex hormones, HRT, and lipid and cholesterol metabolism Flashcards
Serious and common adverse effects of combined OCP?
arterial and venous thromboembolism, PE, GB disease, hypertension- Na+ and H20 retention occurs- RAAS stimulation? exertion of similar effects to aldosterone?
precipitate porphyria, increase risk of stroke in women with focal migraine, MI
abnormal menstruation, breakthrough bleeding, breast tenderness, bloating symptoms, migraine, weight change
when is combined OCP contraindicated?
pregnant- already increased risk of DVT women >35 and smoke- assoc risk of thrombotic CVS events prolonged immobolisation thrombotic disorders CAD endometrial cancer liver tumours
risk if women being treated for TB is only using the combined OCP for contraception?
may get pregnant as rifampicin= CYP 450 inducer, so will cause increased metabolism of COCP, so it may become ineffective.
actions of oestrogens?
mild anabolic
sodium and water retention
raise HDL, lower LDL
decrease bone resorption (so post-meopause- risk of osteoporosis)
impair glucose tolerance
increase blood coagulability
?improve mood, concentration, reduce Alzheimer’s
?avoiding 1st pass effect more favoruable
progesterone actions?
anabolic secretory endometrium fluid retention increased bone mineral density mood changes
SEs of progesterone?
weight gain fluid retention anabolic acne nausea, vomiting irritabolity PMS, depression concentration lack
actions/SEs of testosterone?
*remember, determinative and regulatory effects
anabolic
male secondary sexual characteristics e.g. increased laryngeal size, hair growth, increase bone density, increased muscle and strength
voice deepening
aggression
acne
metabolic adverse effects on lipids
describe the difference between the monophasic and triphasic COCP?
monophasic: constant dose of oestrogen and progesterone every day for 21 days
triphasic: constant dose of oestrogen, with a dose of progesterone which increases each wk during the 21 days of cycle. triphasic allows total amount of progesterone administered each month to be reduced
what are the different generations of progestogens?
relate to androgenic activity, so 3rd generation e.g. desogestrel have lower androgen receptor cross-reactivity compared to levonorgestrel= 2nd generation, highest androgenic activity on molar basis
clinical relevance of COCP being metabolised by CYP 450 (hepatic)?
efficacy reduced by enzyme inducing drugs e.g. PCBRAS phenytoin carbamazepine barbiturates rifampicin alcohol sulphonylureas
example of anti-oestrogen drug used to treat infertility and explain how it works?
clomiphene:
weak oestrogen that blocks receptors, inhibits oestrogen binding to anterior pituitary so stops -ve feedback of oestrogen, so increases GnRH, FSH and LH and induces ovulation
tamoxifen= also a weak oestrogen, used in oestrogen receptor +ve breast cancer
given an example of an anti-progestogen used for medical termination of pregnancy and induction of labour?
Mifepristone
partial agonist to progesterone receptor, inhibits progesterone action
sensitises uterus to PGs- can be used with a PG cervical ripening agent
what can selective oestrogen receptor modulators be used for?
e.g. raloxifene
action different in various tissues so can selectively inhibit and stimulate oestrogen action in particular tissues
protects against OP
no proliferative effects on endometrium of breast
oestrogenic effects on lipid metabolism, bone and blood coagulation
reduced risk of invasive BC in PM women with OP
increases hot flushes
why can testosterone not be given orally to males who are hypogonadal e.g. due to pituitary or testicular disease? what can be used instead?
testosterone rapidly inactivated by liver- heavily metabolises drug
synthetic androgens e.g. mesterolone- active orally
examples of secondary benefits of statin treatment?
improved endothelial cell function
plaque reduction
anti-inflammatory
reduced thrombotic risk
what are fibric acid derivatives?
ampipathic carboxylic acids which increase prod. of lipoprotein lipase- reduce triglyceride prod, some reduction in LDLs, increase FA uptake and oxidation
direct vascular effects
what is the best agent to raise HDL-C?
nicotinic acid
how does nicotinic acid work in lipid lowering tment?
inhibition of lipoprotein (a) synthesis, lowers VLDLs and increases HDLs
risk with using combination statin and fibrate as lipid lowering tment?
increased risk for myopathy and rhabdomyolysis- gemfibrozil may impair glucuronidation of statins- espec. cerivastatin, fenofibrate has less potential for impairment of statin metabolism
why does use of the progesterone only pill increase risk of ectopic pregnancies?
progesterone reduces motility of fallopian tubes, so reduced peristaltic action that normally allows fertilised ovum to be moved along for implantation in posterior uterine wall. Also, thickened cervical mucus makes transport more difficult.
what to do if miss taking COCP?
if missed 1 anywhere in pack, or started a new pack 1 day late, should take forgotten pill straight away, even if that means 2 in 1 day, carry on taking rest of pack as normal and take 7 day free or with placebo as normal. Extra contraception not needed.
If 2 or more missed, or new pack started 2 or more days late, last pill missed should be taken, any earlier ones left, carry on taking rest of pack as normal, and use extra contracpetion e.g. condoms for next 7 days.
emergency contraception e.g. levonorgestrel may be needed if had unprotected sex in previous 7 days and you’ve missed 2 or more pills in 1st week of pack.
what to do if missed POP?
if 3hrs, or >12 with cerazette, take a pill as soon as you remember – only take one, take the next pill at the usual time – this may mean taking two pills on the same day, carry on taking your remaining pills each day at the usual time, use extra contraception such as condoms for the next two days (48 hours) after you remember to take your missed pill, or don’t have sex
if you have unprotected sex during these two days, you may need emergency contraception
other than drugs inducing CYP450, give another example of drugs that can reduce the efficacy of the COCP?
antibiotics- affect gut flora- can alter entero-hepatic uptake of drug.
factors to consider in a patients PMH and FH in assessing them for prescribing COCP?
blood pressure, BMI diabetes FH of cancers, DVTs epilepsy migraines drug history- interactions?
effect of vomiting after taking COCP?
if within 2-3 hrs of taking pill, it will have not been absorbed and so next pill should be taken on same day.
Also affects absorption if severe diarrhoea.
how should a patient taking COCP be monitored?
BP
weight
lipid levels- if RFs for CVD
what can be measured in the blood to exclude a DVT in patients?
D-dimer- if low then defo. not DVT
why are patients at increased risk of cervical cancer when taking COCP?
less likely to use barrier contraception and so increased risk of exposure to HPV.
function of tibolone?
synthetic steroid hormone which mimics actions of oestrogen and progesterone so can be used in post-menopausal women
example of a drug used to control symptoms in menopausal women, but is not an example of HRT?
clonidine- control vasomotor symtpoms by binding to adrenergic receptors to relax smooth muscle of blood vessels, causing them to dilate.
before surgery, what must a patient do if taking HRT?
must stop it 4-6 wks prior to surgery as HRT increases risk of thrombosis, as does surgery and anaesthetic used.
effect of statins on plasma lipid levels?
reduced LDLs
increases HDLs
reduces triglycerides
effect of ezetimibe (cholesterol esterase inhibitor) on plasma lipid levels?
reduces LDLs
increases HDLs
reduced triglycerides
effect of niacin on plasma lipid levels?
reduced LDLs
increases HDLs- main effect, best for this
reduces triglycerides
effect of cholestyramine ( a bile acid sequestrant) on plasma lipid levels?
reduce LDLs
increase HDLs
increase triglycerides
why would cholestyramine not be used in a patient with hypertriglyceridemia, and what could be used instead?
bile acid sequestrant which inhibits bile acid reabsorption by terminal ileum, increasing hepatocyte bile acid synthesis and increasing triglyceride levels.
could instead use a fibrate e.g. fenofibrate, most common adverse effect of fibrates= GI discomfort, but also risk of myopathy when admin with statin
effect of Omega 3 FA on plasma lipid levels?
increase HDLs
decrease triglycerides
effect of fibrates on plasma lipid levels?
lower LDLs
increase HDLs
reduce triglycerides- good at doing this
contrast simvastatin and rosuvastatin
simvastatin= cheaper, shorter 1/2 life (1-4hrs) so must be taken at night which patients may not be compliant with rosuvastatin= more potent, longer 1/2 life (20 hrs) so can be taken at any time of day.
mechanism of action of a fibrate?
PPARalpha (peroxisome proliferator-activated receptor) (transcription factor) activation- increases apoA-I and apoA-II synthesis in hepatocytes to increase HDLs.
-reduces apoC-III synthesis in hepatocytes and increases lipoprotein lipase expression in muscle vascular beds, which increases FA uptake in muscle cells and their oxidation in these cells which reduces plasma triglycerides.
-increases FA oxidation in hepatocytes- reduces triglyceride synthesis to reduce plasma triglycerides.
also, reduces FA and triglyceride synthesis in hepatocytes lowers LDLs, and increases LDL particle size.
also direct vascular effects
lipid-lower drug of choice in patient with familial hypertriglyceridaemia?
fibrate e.g. fenofibrate
why are chylomicrons and VLDLs not atherogenic?
greater size prevents them from passing into blood vessel walls
how are HDLs anti-atherogenic?
remove cholesterol from artery walls
summarise the development of atheroma in arteries?
endothelial damage e.g. by LDLs- platelets and moncytes migrate, PDGF released- stimulates SMCs- take up LDLs-foam cells- fatty streak, also release collagen- fibrous plaque- cap can rupture, then subintima= focus for thrombosis. LDLs oxidised by free radicals release from endothelial cells, macrophages and SMCs. Macrophages uptake oxidises LDLs, form foam cells, and release cytokine that attract more inflammatory cells, stimulate SMC proliferation and migration from media into intima.
target cholesterol conc in those who have had MI?
4 mmol/L
normal target level= <5
normal triglyceride level in blood?
<1.7mmol/L
why might a statin not work effectively in a patient with homozygous familial hypercholesterolaemia (type IIa hyperlipoproteinaemia)?
patient has absence of functional LDL receptors, and main way in which statins work is by increasing number of LDL receptors.
why is LDL receptor number increased with statins?
inhibiting hepatocyte synthesis of cholesterol through HMG-CoA reductase inhibition- rate-limiting enzyme in cholesterol synthesis, reduces cholesterol in hepatocytes, stimulating increased LDL receptor expression.
this increases clearance of LDLs, by increasing LDL uptake from plasma and so reduces plasma LDL-cholesterol, and also IDLs, statins also reduce prod of LDLs and VLDLs.
why should a statin not be given to a pregnant patient?
cholesterol essential for normal fetal development?
aside from fibrates, what other drug used in combination with a statin increases risk of myopathy?
nicotinic acid/niacin
total cholesterol conc defining primary hypercholesterolaemia?
> 7.5mmol/L
why is a statin beneficial to a patient who has suffered an acute MI, despite their cholesterol levels being in the normal range?
has other effects which reduce CVD events risk e.g. reducing thrombotic risk, improving endothelial function, plaque reduction and anti-inflammatory
pro-atherogenic effects of oxidised LDLs?
toxic to endothelial cells
enhance platelet aggregation
induce T-cell activation and VSMC division/differentiation
inhibits macrophage motility
1st choice drug for both primary and secondary prevention of CVD?
statin- also been shown to be effective in reducing CVD risk for high risk-patients e.g. diabetics with average or even below average LDL-cholesterol levels
for what disease is a statin recommended for all patients?
familial hypercholesterolaemia
what must be promoted first in patients before adminstering lipid-lowering drugs?
therapeutic lifestyle changes: reduce dietary saturated fat and cholesterol intake, weight reduction, increase physical activity, stress reduction.
how do statins reduce triglyceride levels?
decrease VLDL production (carry liver synthesised TAGs to AT), and increased clearance of remnant lipoproteins by liver.
most potent statins and why?
rosuvastatin and atorvastatin
due to differential metabolism- rosuvastatin not metabolised by CYP450 pathway, atorvastatin= P450 3A4.
rosuvastain- longer t1/2
adverse effects of statins?
myopathy and/or myositis with rhabdomyolysis- very rare, occurs at high doses of most potent statins so don’t routinely monitor CK levels
increased transaminase levels
GI complaints, arthralgias, headaches
what statin and dose is recommended for primary prevention of CVD in those with a 10% or greater risk of a CVD event in the next 10 yrs?
atorvastatin- 20mg, daily
indications for fibrate tment?
hypertriglyceridemia
combined hyperlipidaemia with low HDL and not responded to nicotinic acid
adjunctive therapy to diet
SEs of fibrates?
GI upset
cholelithiasis
myositis- mypathy more likely if combined with statin-gemfibrozil fibrate
abnormal LFTs
contraindications for fibrates?
hepatic or renal dysfunction
existing GB disease
adverse effects of nicotinic acid?
flushing and pruritis- reduced by timed-release formulations, and given aspirin or other NSAID beforehand. flushing mediated by PG release within skin following mediation by niacin GPCR.
Hepatotoxicity, GI (sustained-release)
Activation of peptic ulcer
Hyperglycemia and reduced insulin sensitivity
contraindications for nicotinic acid?
acute liver disease or unexplained LFT elevations
peptic ulcer disease
mechanism of action of ezetimibe?
selectively inhibits intestinal cholesterol absorption- inhibits cholesterol delivery to liver, increases hepatic LDL receptor expression and reduces cholesterol content of atherogenic particles.
ADRs of ezetimibe?
headache
abdominal pain
diarrhoea
usefulness of ezetimibe and its active glucuronide metabolite circulating enterohepatically?
delivers agent back to site of action, reduces systemic exposure
by how much can fish oils reduce triglyceride levels by in patients with hypertriglyceridemia?
up to 50%
tment with statin in secondary prevention guidelines?
atorvastatin 80mg in people with CVD
when might a statin be contraindicated?
patient with history of liver disease, high alcohol intake
pregnant
how do bile acid sequestrants e.g. cholestyramine work?
inhibit bile acid reabsorption in terminal ileum, so cause upregulation of bile acid synthesis by the liver, which reduces hepatic cholesterol concentration and stimulates increased LDL receptor expression, removing LDL-cholesterol from the blood.
however, up-regulation of hepatocyte cholesterol and TG synthesis, increasing VLDLs and so increasing TG levels.
drug of 1st choice for moderate hypertriglyceridaemia?
statin
what problems is the synthetic oestrogen DES (diethylstillbestrol) associated with?
cancers e.g. vaginal and uterine abnormalities
example of a derivative oestrogen analogue (from ethinyl oestradiol) used in HRT?
quinestrol
which hormone could be administered to prevent pre-term labour?
progesterone
*REMEMBER, decrease in progesterone to oestrogen ratio increases PG synthesis which mediates cervical ripening, cause uterine smooth muscle contractions by enhancing Ca2+ release from IC stores, and ratio decrease also increases oxytocin receptor pop in myometrium, and oxytocin lowers threshold for AP triggering.
how could the growth of cancers dependent on dihydrotestosterone be reduced?
by administering a 5alphareductase inhibitor, as this enzyme is responsible for dihydrotestosterone prod. from testosterone.
type of progesterone used in depot provera (long acting release once injected)?
medroxy progesterone acetate= long t1/2- around 40 days
injected every 3 mnths.
etonogestrel is a progesterone used in what?
female implants
male implants
vaginal ring
2 different ways of giving combined HRT?
sequential and continuous
sequential= progesterone is only given for 1/2 of cycle so given at day 12-14), and so this allows for a withdrawl bleed, which is safer, reducing risk of endometrial hyperplasia.
continuous= same dose of progesterone over 28 days so don’t bleed.
risks of HRT?
Unopposed oestrogen: increase endometrial cancer,
and ovarian cancer
Increased Breast cancer
Increased Ischaemic Heart Disease, and stroke
Increase risk of venous thromboembolism- at risk more if orally given as passes through liver where metabolites produced have unknown effects.
Uterine bleeding
Adverse effect on lipid profile
Adverse effect on thrombophilia profile
ways in which HRT can be administered?
oral transdermal nasal implant transvaginal
cyproterone is an anti-androgen. How does it work and what is it most commonly used for?
partial agonist to progesterone receptor (as derivative of progesterone), competes with dihydrotestosterone.
used for hirsuitism e.g. in PCOS
also used in combined contraceptive pill
raloxifene, a SERM, can be used in the tment of what disease?
osteoporosis in post menopausal women.
exerts effect of oestrogen to inhibit bone resorption.
why is POP required to be taken every day?
short t1/2 of progesterone, so rapidly eliminated from body and so short time frame within which therapeutically active.
describe the PKs of oestrogen in body?
lipid soluble, so taken up by AT (large Vd in obese women), and released slowly.
therefore, lower concns in plasma acheieved in obese women, but increasing dosage may increase risks of SEs e.g. DVT and hypertension.
why do OATP2 inhibitors reduce the efficacy of statins?
The OATP2 transporter is used by statins in order for them to be actively uptaken into hepatocytes, which is where they then act to produced a desired therapeutic effect so inhibitors stop them from being uptaken to their site of action.
more then stays in plasma which increases likelihood of off target ADRs e.g. myopathy and headaches.
failure rate of the OCP when taking phenytoin or carbamazepine (CYP 450 inducers)?
5-10%
this is up from the normal baseline rate of 1-2%
