Question:
Since Viagra has been very variable to me, I'll try injections. My
first go will probably be pure Papaverine. I know it's cheap and can
be stored for a long time (even in room temperature?). Are there other
advantages? What about disadvantages?
If it fails I have the otion of moving on to Bi-mix
(Papaverine/Phentolamine). Advantages/disadvantages compared to just
Papaverine?
Answer:
This I think provides a good description of agents used for intracvernosal
injection....
It's from this site....
http://www.powerpak.com/CE/Pfizer-ED/lesson.cfm
you have to scroll down quite a ways...so I copied it to post here and I
want a copy myself. I inject Trimix.
"intracavernosal injection.35,53
The intracavernosal dose may vary with age and etiology of erectile
dysfunction, from 10 mg initially to a maximum of 60 mg for older patients
with vasculogenic erectile dysfunction.3 When given in combination with
phentolamine, the dose is reduced.35 The number of responders to papaverine
monotherapy is reported to be low, about 35%, compared to 65% when combined
with phentolamine.54
Patients should be monitored for prolonged erections. Prolonged erection
when papaverine is used alone is seen in up to 10% of patients.53 Local
complications such as subcutaneous hematomas and pain occur. Longer-term use
of intracavernous injections of papaverine may induce corporeal fibrosis,
corporal nodules, and plaques or fibrosis. This may be due to the acidity of
papaverine solutions (pH 3 to 4) which cannot be corrected by the use of a
buffer due to precipitation at a pH greater than 5.50.
Systemic effects include vasovagal reaction, bradycardia, hypotension,
dizziness, and facial flushing. Papaverine is potentially hepatotoxic.50 The
incidence of drug-induced hepatitis is less than 1 in 1000 in patients with
normal liver function, but may be seen in 1 of 100 patients with existing
elevated transaminase levels.
Phentolamine-Phentolamine mesylate (Regitine®) is an alpha-adrenergic
receptor blocker. By blocking sympathetic activity on smooth muscle,
phentolamine causes dilation of penile arterial vessels. Phentolamine is not
very effective for the treatment of erectile dysfunction when used as
intracavernosal injection monotherapy. It is usually given in combination
with other agents such as papaverine and alprostadil. After intracavernosal
injection, phentolamine reaches a maximum serum concentration within 30
minutes, and declines rapidly to undetectable levels.53 Phentolamine has a
short plasma half-life of 30 minutes and is extensively metabolized by the
liver. The amount of phentolamine used for intracavernosal injection
mixtures commonly varies from 0.5 to 20 mg, with a usual dose around 1 to 2
mg. Systemic adverse effects may include orthostatic hypotension and
tachycardia. These effects are reduced when used in lower-dose combinations
with other vasoactive agents.
Prostaglandin E1 or Alprostadil-Alprostadil, or PGE1, is an analogue of
arachidonic acid. Alprostadil has alpha-blocking properties in the penile
tissue which causes relaxation of the cavernous and arteriolar smooth muscle
while causing restriction of venous outflow. Alprostadil is the only
injectable medication formally approved for the treatment of erectile
dysfunction. The two products available are Caverject® (Pharmacia-Upjohn)
and Edex® (Schwarz Pharma). It can be used either as monotherapy or in lower
doses in combination with other vasoactive agents. Alprostadil that enters
systemic circulation is quickly metabolized, primarily by the lungs.35 The
plasma half-life of alprostadil is less than one minute.
The initial dose is usually 2.5 mcg. The dose is increased, if necessary, on
subsequent office visits until a satisfactory response is obtained. The goal
is to produce an erection that is satisfactory for sexual activity and is
maintained for no longer than one hour.35,50 The maximum recommended dose is
40 mcg for Edex® 55 and 60 mcg for Caverject®.56 The average therapeutic
dose is higher in older compared to younger men (21 mcg versus 12.5 mcg,
respectively).3 This is likely because of the higher prevalence of arterial
occlusive disease in older people. In a study by Garceau et al,57 the
average effective dose of alprostadil differed depending on the cause of
erectile dysfunction; in men with vascular causes, the dose averaged 19.1
mcg; psychogenic causes, 11.5 mcg; and neurogenic causes, 15.3 mcg. The
efficacy of alprostadil has been documented to be about 75% in doses between
10 to 20 mcg intracavernously, with doses as low as 2.5 to 5mcg occasionally
being effective.53 Patient and partner satisfaction after injection was
reported in up to 87% of partners.58"
