What are the two main ways drugs can affect sexuality?
- alteration of libido
- alteration of performance (erection/lubrication/orgasm)
what hormones increase libido in males and females?
which hormone increases libido in females only?
what hormones decrease libido in males and females?
norepinephrine (alpha 2)
what hormone decreases libido in men?
estrogen (feeds back and lowers T levels)
what are the parasympathetic nerves involved in penile or clitoral erection/lubrication?
what are the sympathetic nerves involved in ejaculation in men and contraction of the uterus, fallopian tubes and vagina in women?
what are the somatic nerves that contribute to erection and orgasm?
the typical effect of drugs that interferes with erection are what two things?
- peripheral anti-muscarinic actions
- decreased blood flow
the typical ways in which drugs act to decrease libido are:
increasing prolactin secretion
blocking androgenic action (anti-androgenic)
Block Dopamine, NE or ACh (muscarinic)
the most common ways drugs interfere with orgasm are:
alpha 1 blockade
what are the treatments for premature ejaculation? What is the most significant side effect?
drugs that delay orgasm:
thioridazine (neuroleptic antipsychotic)
***but, these drugs also inhibit libido
what are some drugs that enhance libido?
Testosterone (both males and females - lower doses in females)
Bromocriptine -used in prolactinemia
Apomorphine - in clinical trials
what is a major drug-induced cause of impotence?
what was commonly used before PDE5 inhibitors to treat ED?
Prostaglandin E1 (alprostadil)
injectable and uretrhal suppository
acts by vasodilating
SE: hypotension, mild penile pain, occasional priapism
what are the differences among the PDE5 inhibitors?
pharmacokinetics and price
what is the MOA of PDE5 inhibitors?
NO acts on a pathway in the endothelial and or neural cells to convert guanylate cyclase and GTP into cGMP, which leads to musclar relaxation of the corpora cavernosa and then erection
the "off" switch for this pathway converts cGMP into GMP using PDE5 the inhibtors block this "off" switch
what are the pharmacokinetics of sildenafil (viagra)?
peak plasma concentrations at 1 hour - take 1 hour prior to intercourse
half-life 4 hours (short)
what is the pharmacokinetics of Cialis (tadalafil)?
half-life is 18 hours (effective 36)
peak concentration is 1-6 hours
what are the adverse effects of PDE5 inhibitors?
hyptension (average decrease 9/6)
common: headache, flushing, indigestion
less common: visual disturbance, actue hearing loss, nasal congestion, diarrhea, rash
How are the PDE5 inhbitors metabolized?
what kind of hearing loss has been reported with PDE5 inhibitors?
unilateral, 1/3 temporary, sometimes with vertigo, tinnitus and dizziness
what kind of reports of vision loss have there been with PDE5 inhibitors?
nonaerteritic ischemic optic neuropathy
progressive, usually after continual use
partial vision loss, but permanent
small # cases 15-20
what are the potential serious interactions with nitrates for the PDE5 inihibitors?
large decrease in BP, syncope, lower cardiac perfusion, MI
don't forget that nitrates includes nitroprusside and recreational drugs like amyl nitrate and butyl nitrate