IC15 Pharmacology of Women's and Men's health drugs Flashcards
What is tamsulosin?
What is the pathophysiology of BPH?
What is the MOA of tamsulosin?
MOA Alpha 1A adrenoreceptor antagonist
- Specific alpha 1A (bladder and lower urinary tissues)
- Does not affect adrenoreceptors on heart
- Reversible inhibition of Alpha1A receptor, prevents vasoconstriction and muscle constriction of bladder sphincter, urethra and prostate
- Reduce urinary obstruction, increase urinary flow rate
- Significantly delay need for surgery or catherization
(Pathophysiology:
- Adrenergic nerves releases noradrenaline
- Noradrenaline released acts on adrenoreceptors and cause muscle constriction of bladder sphincter, urethra and prostate
- Urinary obstruction, reduced urinary flow)
What is tamsulosin indicated for?
BPH
What is the PK profile of tamsulosin?
PK
A: oral, OD, Works in hours or days (fast onset)
D: minimal distribution, highly PPB
M: CYP3A4, CYP2D6
E: Urine
What are the ADRs of tamsulosin?
ADR:
1. Abnormal ejaculation
2. Back pain
What are the special considerations of tamsulosin?
Special Considerations
DDI:
- Grapefruit, pomelo
- CYP3A4 and CYP2D6 inhibitor and inducer
CI:
- Avoid other a1-adrenoreceptor antagonist e.g. prazosin, epinephrine –> can cause excessive muscle relaxation and hypotension
What is finasteride?
What is the pathophysiology of BPH? (static component)
What is the MOA of finasteride?
MOA 5apha-reducatase inhibitor
- Competitively inhibits 5a-reductase
- Prevents conversion of testosterone to DHT
- Reduces prostate size
- Increase urine flow and reduce frequency of acute retention of urine
- Reduce need for surgery
- Lower PSA
Physiology:
- 5a-reductase converts testosterone to dihydrotestosterone (DHT)
- DHT leads to increase prostate size and hair loss in males
What is finasteride indicated for?
Clinical Indications
1. BPH
2. Hair loss (Propecia)
3. Hirsutism
What is the PK profile of finasteride?
PK
A: oral, OD, takes 6 months to exert effects (slow onset)
D: highly plasma protein bound
M: CYP3A4
E: urine and feces (NO need adjustment when renal impaired, liver impaired or elderly)
What are the ADRs of finasteride?
ADR
1. Loss of libido and sexual potency
2. Gynecomastia (rare)
What are the special considerations of finasteride?
Special Considerations
DDI:
- Grapefruit, pomelo
- CYP3A4 inhibitor and inducer
CI:
- Avoid in women, children or pregnancy
What is sidanefil?
What is the pathophysiology of ED?
What is the MOA of sidanefil?
MOA Phosphodiesterase-5 inhibitor (PDE5i)
- Specific to penis since PDE5 highly expressed in corpora cavernosa but poorly in myocardium
- Inhibits PDE5 in penis which prevents degradation of cGMP
- Increases cGMP
- More can be used for smooth muscle relaxation
- More blood flow to the corpora cavernosa
Physiology:
- Sexual stimulation release NO
- NO increases cGMP
- cGMP triggers signal transduction
- arteriole relaxation
- a lot of PDE5 in corpora cavernosa
- PDE5 degrades cGMP –> preventing arteriole relaxation –> less blood flow to the penis for erection
What is sidanefil indicated for?
ED
What is the PK profile of sidanefil?
PK
A: oral, OD, fast onset
D: widely distributed
M: CYP3A4 (major), CYP2C9 (minor)
E: Feces (NO need to adjust when renal impaired, liver impaired and elderly)
What are the ADRs of sidanefil?
ADR
- Headache
- Flushing
- Dyspepsia
- Dizziness
- Back pain
- Blur vision, blue-green tinting of vision (inhibit PDE6)
- Priapism (prolong erection)
What are the special considerations of sildanefil?
Special Considerations
DDI:
- Grapefruit, pomelo
- CYP3A4 and CYP2C9 inhibitor and inducer
CI:
- Avoid in patients taking GTN (glyceryl trinitrate) –> both increase cGMP –> marked vasodilation and hypotension
What is the MOA of ethinyl estradiol?
MOA:
Estrogen receptor agonist
- Binds to estrogen receptor
- Inhibits FSH release –> prevents development of ovarian follicle
- Create unsuitable endometrium for implantation of ovum
What is ethinyl estradiol indicated for?
Clinical Indications:
1. Menopausal issues
2. Gynaecological disorders
3. Some hormone sensitive cancers
What is the PK profile of ethinyl estradiol?
PK
A: oral, OD, fast onset
D: highly plasma protein bound
M:
Phase I: hydroxylation by CYP3A4
Phase II: glucuronidation, sulfation (EE sulfate undergo enterohepatic recirculation, increase t1/2)
E: urine and feces
What are the ADRs of ethinyl estradiol?
ADR
1. Breast tenderness
2. Headache
3. Fluid retention (bloating)
4. Nausea
5. Dizziness
6. Weight gain
7. VTE
8. Myocardial infarction, stroke
9. Liver damage
What are the special considerations of ethinyl estradiol?
Special Considerations
DDI:
- CYP3A4 inhibitor and inducer
CI:
- Patients with arterial or venous thrombosis
- Advanced diabetes AND vascular disease
- Hypertension >160/100mmHg
- Breastfeeding (<21 days postpartum)
- Patients with breast cancer
What is the MOA of norethindrone?
MOA:
Synthetic Progesterone
- Progesterone receptor agonist
- Inhibits LH secretion –> prevents ovulation
- Create unsuitable endometrium for implantation of ovum
What is the clinical indication of norethindrone?
Clinical Indications:
1. Contraception
2. Endometriosis
3. Abnormal periods
What is the PK profile if norethindrone?
PK
A: oral, OD, fast onset
D: highly plasma protein bound
M: reduction, glucuronidation, sulfation
Some metabolized in liver become EE (take note of EE side effects)
E: urine and feces
What are the ADRs of norethindrone?
ADR
- Headache
- dizziness
- bloating
- weight gain
- Breakthrough bleeding (initial)
- Amenorrhea
What are the special considerations of norethindrone?
Special Considerations:
- Not good for women planning pregnancy, since ovulation suppression may last up to 1.5 years
- Take note of EE ADR e.g. VTE
What is the absorption / ROA for all 5 drugs?
oral oral oral oral oral
What is the PPB for all 5 drugs?
High High - High High
How are all 5 drugs metabolised?
- CYP3A4
CYP2D6 - CYP3A4
- CYP3A4 (major)
CYP2C9 (minor) - Liver (I & II)
CYP3A4 Hydroxylation
Glucuronidation
Sulphation - Liver (I & II)
Reduction
Glucuronidation
Sulphation
How are all 5 drugs excreted?
- Urine
- Urine and feces (no need renal/liver adjustment or elderly)
- Feces (no need renal/liver adjustment or elderly)
- Urine and feces
- Urine and feces