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an area involved in the initiation of erection
during sexual stimulation. The onset of effect is within 20 minutes. With
efficacy rates of 46-55%, studies suggest that apomorphine is not quite as
effective as PDE5 inhibitors.(16) It can be used in the presence of other
conditions such as diabetes, ischaemic heart disease and depression and concomitant
medications (including nitrates) are not contraindicated, although caution in those susceptible to
hypotension is required.(17) Side effects include nausea and the potential to lower blood pressure
when taken with alcohol in some individuals.
Second line treatments
Intracavernosal injections
This treatment is useful where PDE5 inhibitors have failed or are contraindicated. They work by
directly relaxing the smooth muscle lining the vascular spaces in the corpora cavernosum.18 Unlike
PDE5 inhibitors, no sexual stimulation is required for the injections to work. However, patients do
require adequate instruction in injection technique (Figure 2) and dosage titration. Side effects
include pain at the site of injection, priapism, and in long term use, scarring of the tunica albuginea
with potential curvature and shortening of the shaft of the penis. Alprostadil (Caverject) is the
most common injection used in Australia.
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Figure 2. Intracavernosal self injection technique
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