Women's Health, Men's Health Flashcards
What is tamsulosin indicated for?
Moderate-severe symptomatic BPH
(regardless of prostate size)
What is the MOA of tamsulosin?
MOA: reduces vasoconstriction induced by endogenous catecholamines by blocking the α-adrenoreceptors on the smooth muscle
- Decreases muscle tone
- Reduces bladder obstruction – relaxes prostate smooth muscle to improve urinary flow rate
How is tamsulosin selective for the prostate?
selective for α1A receptors (prostate) over α1B receptors (cardiac), so it favors selectivity for the prostate
How is tamsulosin administered?
PO
Does tamsulosin bind to plasma proteins?
> 90%
What is the Vd of tamsulosin?
0.2L/kg
How is tamsulosin metabolised?
by CYP enzymes in the liver
What is the half life of tamsulosin?
10-15h
How is tamsulosin eliminated?
10% excreted unchanged in urine
How long does it take for the onset of tamsulosin’s effects?
Fast, takes days to weeks
What are the adverse effects associated with tamsulosin?
Abnormal ejaculation, back pain, muscle weakness, fatigue
What are the contraindications for tqmsulosin?
Concurrent use of another α1-adrenoreceptor antagonist
What is the MOA of finasteride?
Competitively inhibits 5α reductase (Type II), which decreases conversion of testosterone to DHT, resulting in ↓prostate size
What is finasteride indicated for?
Moderate or severe LUTS w large prostate (>40g)
How long does it take for the onset of finasteride’s effects?
Slow, may take up to 6-12 months to decrease prostate size
How is finasteride administered?
PO
What is the bioavailability of finasteride?
0.65
Does finasteride need dose adjustments?
No - renal, liver, old age
Is finasteride highly protein bound?
Yes (~90%)
How is finasteride metabolised?
By liver CYP enzymes
What is the half life of finasteride?
~6h
How is finasteride excreted?
50% excreted unchanged in faeces
Metabolites are excreted in urine and faeces
What are the adverse effects of finasteride?
- Ejaculatory disorders (reduced semen or delayed) – more common than α1 antagonists
- Decreased libido (3-8%)
- Erectile dysfunction (3-16%)
- Gynecomastia and breast tenderness (1.0%)
- Lesser risk of hypotension
- More hair growth – reducing conversion of testosterone to DHT means testosterone levels are higher, resulting in increased hair growth
What are the contraindications for finasteride?
Women and children, pregnancy
What is the MOA of sildenafil?
Inhibit PDE5 enzyme (breaks down cGMP), resulting in increased cGMP activity, inducing smooth muscle relaxation to cause an erection
Why is sildenafil v selective for the penis?
PDE5 is highly expressed in the corpora cavernosa of the penis and its vasculature, but poorly in the myocardium, which provides tissue specificity for the penis
How is sildenafil administered?
PO
What is the bioavailability of sildenafil?
~40%
How long does it take for the onset of sildenafil?
30-60min
How long can the effects of sildenafil last?
maximum of 12h
Does sildenafil need dose adjustments?
No - renal, liver, old age
Is sildenafil distributed by the body well?
Yes
How is sildenafil metabolised by the body?
Liver - mainly CYP3A4 (and a bit of CYP2C9)
How long is the half-life of sildenafil?
~4h
How is sildenafil excreted?
Metabolites largely excreted in faeces (~80%), minorly in urine (13%)
Unchanged drug excreted in urine
What are the adverse effects associated with sildenafil?
- Headache
- Flushing
- Dyspepsia
- Dizziness
- Back pain
- Blur vision/Blue green tinting of vision
- Priapism
What are the contraindications for sildenafil?
Any patient on GTN should not be taking any PDE-5i
- potentiates vasodilation effect of GTN via inc cGMP due to concomitant blockade of cGMP degradation by sildenafil
- results in potentially life-threatening hypotension
What is the MOA of ethinyl estradiol?
Synthetic estrogen
- reduces FSH release from anterior pituitary to suppress the development of the ovarian follicle (endometrium unsuitable for ovum implantation)
How is ethinyl estradiol administered?
PO, parenterally, transdermal or topically
What is the bioavailability of ethinyl estradiol?
0.45
How long does it take for the onset of ethinyl estradiol?
30-60min
Does ethinyl estradiol exhibit high plasma protein binding?
Very high plasma potein binding (~98%)
How is ethinyl estradiol metabolised>
Metabolised by liver via
Phase I – hydroxylation by CYP3A4
Phase II – conjugation w glucuronide and sulfation into hormonally inert Ethinylestradiol glucuronides and Ethinylestradiol sulfate
Ethinylestradiol sulfate undergoes enterohepatic recirculation
What is the half-life of ethinyl estradiol?
13-27h
How is ethinyl estradiol excreted?
Metabolites excreted in faeces and urine
What are the adverse effects associated with ethinyl estradiol?
- breast tenderness
- headache
- fluid retention (bloating)
- nausea
- dizziness
- weight gain
rare:
- venous thromboembolism
- MI
- liver damage
What is ethinyl estradiol contraindicated for?
- Patients w known Hx or at high risk for VTE
- Advanced diabetes w vascular disease
- Hypertension (>160/100mmHg)
- Avoid in breastfeeding (<21 days postpartum) and breast cancer
What is the MOA of norethindrone
Synthetic progesterone
- reduces LH release to prevent ovulation (makes endometrium unsuitable for ovum implantation)
- progesterone receptor agonist
How is norethindrone administered?
PO
What is the bioavailability of norethindrone?
0.64
Is norethindrone highly plasma protein bound?
Yes
How is norethindrone metabolised?
Metabolised in liver by reduction, followed by glucuronidation and sulfation
What is the half-life of norethindrone?
8h
How is norethindrone excreted?
Metabolites excreted in urine (~50%) and faeces (~40%)
