Androgen Pharmacology Flashcards
Describe the function and location of
FSH
Testosterone
LH
FSH from pituitary controls spermatogenesis in seminiferous cells
Testosterone produced in Leydig cells is also required for spermatogenesis
LH from pituitary stimulates androgen (testosterone) production in Leydig cells.
- Pituitary begins to secrete LH and FSH at ___
- After (__) levels of testosterone are regulated by ___
- Episodic firing of peptidergic neurons in arcuate nucleus results in pulsatile release of ___ –> pulsatile release of LH (lesser amounts of FSH) from the pituitary
puberty / puberty
negative feedback at level of pituitary via testosterone interaction with pituitary receptors
GnRH
- Pituitary begins to secrete LH and FSH at ___
- After (__) levels of testosterone are regulated by ___
- Episodic firing of peptidergic neurons in arcuate nucleus results in pulsatile release of ___ –> pulsatile release of LH (lesser amounts of FSH) from the pituitary
puberty / puberty
negative feedback at level of pituitary via testosterone interaction with pituitary receptors
GnRH
Most important androgen in muscle and liver
testosterone
Hypogonadal levels of testosterone are
<200 ng/dl
DHT is predominant androgen mediator in some tissues including
- prostate
- reproductive tissue (penis-scrotum)
- hair
- Conversion to DHT blocked by the enzyme inhibitors __ and ___
- Converted to estrogen by ___ in peripheral tissues
finasteride (type II)
- (Proscar® [prostate cancer],
- Propecia® [hair loss])
Dutasteride (type I and II)
-(Avodart® [prostate cancer])
CYP19 aromatase
Function of testosterone
- puberty associated changes in males (secondary sex characteristics)
- essential in utero
- Growth-promoting properties (increase muscle mass, skeletal growth)
- closing of epiphysis via conversion to estrogen
- psychologic/behavioral changes via direct effects on CNS
Describe the clinical uses of physiological testosterone replacement
- Hypogonadal boys (HD if def. occurs prior to sexual maturation)
- Osteoporosis (+/- estrogens)
- muscle wasting associated with AIDS
- HRT in aging med in controversial (only for T def. NOT impaired spermatogenesis)
- Abuse in sports via anabolic effect
Androgen deficiency related symptoms
- low libido
- decreased ED
- small testes
- low bone mineral density
- Gynecomastia
- Non-specific: fatigue, depression, anemia reduced muscle strength, increased fat
Symptoms related specifically to androgen deficiency in aging males include: A. Fatigue B. Increased fat C. Low libido D. Depression E. Low bone mineral density
C. Low libido**
E. Low bone mineral density
All anabolic hormones tested also have ____ type of side effects including:
Androgenic side effects
- block of LH-FSH release
- promotion of prostate growth
Consequences of Steroid abuse
- Infertility
- Gynecomastia
- testicular atrophy
- baldness and excessive body hair
- short stature
- tendon rupture
- increased LDL and decreased HDL
- HTN
- MI and CVA
- increased risk of hepatitis/HIV/infection
Which of the following natural or synthetic steroids has both anabolic activity and androgenic activity in humans? A. Testosterone B. Methyltestosterone C. Oxandrolone D. Nandrolone E. Stanozolol F. All of the above
F. All of the above
Why has modifying the T molecule and/or changing administration routes so important for T meds?
T has excellent oral absorption but rapid hepatic degradation –> therefore difficult to maintain normal T levels
Parenteral/IM T type and MOa
T ethanate
T cypionate esters
Increased lipophilicity - after IM dose sequestration with gradual release from vehicle
Parenteral T
T ethanate
T cypionate esters
Advantages and disadvantages of IM T.
Advantage: will initiate and maintain normal virilzation in hypogonadal men given every 1-3 weeks
Disadvanatage: less frequent injections an d greater fluctuations in serum T, which can result in fluctuations in energy, mood and libido
Advantages and disadvantages of oral T
Advantage: 17-a-alkylated androgens have reduced 1st pass metabolism
Disadvantage: hepatic SE diminished use