contraceptives Flashcards
a blocker eg
- Alfuzosin
- Tamsulosin
- Silodosin
non-selective: doxazosin, terazosin, prazosin
prostate physiology
1) prostate smooth muscle maintained by noradrenaline (from adrenergic nerves)
2) Stimulate post-junctional a1-adrenoceptor
3) Prostate and LUT tissue exhibit
a) High proportion of a1A receptors
a1 receptor antagonist MOA
- Antagonist of a1A receptor = relax smooth muscle of bladder (int. sphincter) & urethra
○ improve urine flow - Reversible antagonist
○ Inhibit vasoconstrict by endogenous catecholamines
○ Block a1-adrenoceptors on smooth muscle of
§ Prostate, prostatic urethra, bladder neck
○ Decr muscle tone, reduce bladder obstruction
○ Relax prostate smooth muscle
○ Improve urodynamics
§ Max urinary flow (less tension in muscle)
§ Less obstruction
a1 receptor antagonist reduce symptoms of
*Bladder instability
*Tension in smooth muscle of LUT
Improve urinary flow rate (after few hrs/ days)
PK of a1 receptor antagonist
A: well absorbed orally (0.4 mg OD)
D: highly bound to plasma proteins (90-99%)
Small Vd (0.2L/kg)
M: CYP (3A4, 2D6)
T1/2: ~10-15h
E: urine
ADR OF a1 receptor antagonist
- Abnormal ejaculation
- Backpain
when is a1 receptor antagonist used
- Moderate-severe symptomatic BPH regardless of prostate size
- Selective for a1A (prostate, blood vessels) > a1B (blood vessel, heart)
- less effect on BP- LT therapy to maintain effect of urinary storage, voiding symptoms
*Delay surgery, catheterisation
- LT therapy to maintain effect of urinary storage, voiding symptoms
CI of a1 receptor antagonist
Concurrent use of another a1-adrenoceptor antagonist
- prazosin, epinephrine
5a reductase inhibitor eg
Finasteride, dutasteride
5a reductase in normal physiology
- Testosterone –> dihydrotestosterone (DHT)
○ Prostate to grow
○ Male pattern hair loss (androgenetic alopecia)
5a reductase inhibitor MOA
- Competitive, 5a-inhibitor (no affinity for androgen receptor)
- Inhibit conversion of Testosterone –> dihydrotestosterone (DHT)
○ In male external genetelia - Decr prostate size
○ Inr urine flow
○ Reduce freq of ACUTE retention of urine - Decr need for surgical procedures for prostate transurethral resection, prostatectomy
- Inhibit conversion of Testosterone –> dihydrotestosterone (DHT)
symptom relieve of 5a reductase inhibitor
inhibit 5a-reductase enzyme action
* Decr prostate size
*Incr hair growth
take up to 6mnth to see BPH clinical effect
PSA decr over time
PK of 5a reductase inhibitor
A: well absorbed orally (5mg OD)
f~0.65
No dosage adj for renal insuff/ liver failure/ elderly pt
D: highly bound to plasma proteins (90%)
M: CYP (3A4, 2D6)
T1/2: ~6h
E: 50% unchanged in feces
Metabolites in feces, urine
ADR of 5a reductase inhibitor
- Loss of libido, sexual potency
- Gynecomastia (rare)
clinical efficacy 5a reductase inhibitor
Take up to 6mnths to see BPH clinical effect after initiate
Lower dose used for male pattern baldness
Used for female hirsutism
CI 5a reductase inhibitor
Women and children
Preg
ED risk factors
alcohol
enlarged prostate BPH
psychological factors
sleep disorders
stress
PDE5 inhibitor
Tadalafil (can be used for BPH)
sildenafil, vardenafil, avanafil
PDE5I MOA
- Inhibit phosphodiesterase type 5 (PDE5) in penis
- Sexual stimulation, release NO
- Incr convert GTP –> cGMP levels
○ Decr Ca levels
○ Less cGMP —> 5’ GMP (by PDE5)
- Smooth muscle relaxation
- Incr blood flow to corpora cavernosa
○Produce erection
PDE5 normal physiology
- PDE5: highly expressed in corpora cavernosa (of penis, vasculature)
- Poorly in myocardium
*Tissue specificity to compound
- Poorly in myocardium
PK of PDE5I
A: well absorbed orally (5mg OD/ PRN)
f~0.4
No dosage adj for renal insuff/ liver failure/ elderly pt
Onset 30-60min
Duration ~12h (uncomfortable)
D: widely distributed
M: CYP (3A4, 2C9 -minor) T1/2: ~4h
E: metabolites largely excreted in feces
ADR of PDE5i
- Headache
- Flushing
- Dyspepsia
- Dizzy
- Back pain, muscle pain (PDE11 affinity)
- Blur vision
(inhibit retinal PDE6, blue-green tint of vision)
7.Priapism (prolonged erection
initiate PDE5i
Start Dose: at lowest conc
- esp for >65yrs old
1) Check for cardiac 2) Check dose
CI for PDE5i
- Cardiac pt on GTN (nitroglycerin)
Potentiate vasodil effect of GTN (via incr cGMP) due to incr inhibition of cGMP degradation) - marked vasodilation, hypotension
Ethinyl estradiol
Estrogen receptor agonist
Synthetic estrogen (birth control pills, oral contraceptives)
MOA of estrogen agonist
- Inhibits FSH release from anterior pituitary
- Suppress development of ovarian follicle
* Make endometrium unsuitable for implantation of ovum
PK of estrogen agonist
A: well absorbed orally (OD)
f~0.45
IV, transdermal, TOP too
Onset 30-60min
D: highly plasma protein bound (~98% albumin)
M: metabolised by liver (T1/2 13-27hrs)
E: excreted in feces, urine
metabolism of estrogen agonist
Phase 1: EE hydroxylation (CYP3A4)
Phase 2: conjugation (to inert)
- Glucuronide(ethinylestradiol glucuronides
- sulfation (ethinylestradiol sulfate)
Enterohepatic recirc** (liver, bile, SI, ab by enterocyte, back to LIVER)
ADR of estrogen agonist
1) Breast tenderness
2) Headache
3) Fluid retention (bloat)
4) NV
5) Dizzy
6) Weight gain
- Venous thromboembolism (VTE)
- MI/ stroke
*Liver damage
CI for estrogen agonist
- History/ susceptibility to arterial/ venous thrombosis (VTE)
- Advanced DM with vascular disease
- Hypertension >160/100
- Avoid breastfeeding (21 days postpartum)
- Breast cancer women
indication for ethinyl estradiol
menopausal sx
gynecological disorders
hormone-sensitive cancers
progestin
Norethindrone
progestin uses
- Synthetic progesterone (birth control pill, oral contraceptives)
- treat endometriosis
- abnormal periods of bleeding, for a normal menstrual cycle
progestin MOA
- Inhibit luteinizing hormone release
- Prevent ovulation
- Make endometrium unsuitable for implantation of ovum
- Act as progesterone receptor AGONIST
PK of progestin
A: well absorbed orally (OD)
f~64%
D: highly plasma protein bound (albumin)
M: metabolised by liver (T1/2 8hr)
Phase 1: reduction
Phase 2: conjugation (to inert)
Glucuronide
sulfation
Some % norethindrone metabolised –> EE
E: excreted in feces, urine
ADR of progestin
1) Headache
2) bloat
3) NV
4) Dizzy
5) Weight gain
6) Unpredicted spot/ bleed (initial)
7) Amenorrhea (stop)
partial conversion of norethindrone –>EE*
* Venous thromboembolism (VTE)
* MI/ stroke
* Liver damage
CI for progestin
Not for women planning preg soon after cessation of therapy
- ovulation suppressed may persist for as long as 1.5yrs
structure of estrogen agonist and progestin
estrogen agonist
(from estrogen CH3 —-> Alkynes : allow PO)
progestin
(alter from estrogen agonist, OH –> C=O)
Hypertensive disorders of preg
- Common causes of mortality in pregnancy
○ HTN: 140/90 mmHg
§ Based on >1 measurement, 4hrs apart
§ Start treatment - Severe HTN: >160/110 mmHg (after 2 measurements)
Chronic HTN
Preexisting HTN / New onset HTN
Before 20wks gestation
Gestational HTN
New onset HTN
w/o proteinuria after 20 wks of gestation
Preeclampsia
New onset HTN after 20 wks of gestation w/ any of new onset
1) Proteinuria 2) Sign of end organ dysfunction 3) Uteroplacental dysfunction
Chronic HTN with superimposed preeclampsia
New onset proteinuria in women with chronic HTN, no proteinuria
Before 20 wks gestation
Preeclampsia
complex multisystem disease. Not understood pathophysiology, multifactorial and varied
1) proteinuria
2) signs of end organ damage
Proteinuria
- 24h urinary protein UTP > 300mg
- Dipstick protein > 2 +
- Urine protein:
- creatinine ratio (uPCR) > 0.3 mg/dL
Signs of end organ damage
- PLT platelet < 100
- LFT > 2X ULN
- Double SCr, absence of other renal disease
- Pul oedema
- Neurological complications **
□ Altered mental status
□ Visual disturbances
□ Seizure
□Headache
eclampsia
new onset tonic-clonic, focal, multifocal seizure superimposed on preeclampsia
§ Medical emergency –> risk to both maternal & fetal
§ Complications of eclampsia
Prevention of preeclampsia
Low dose aspirin
□ *high risk pt : □ Dose: 100mg or more daily (low dose) □ Started from 12-16wks. Continue till delivery