Apart from those with severely impaired mental function, there are no contra-indications to injection therapy. Systemic absorption of the drug is minimal, and although it may cause transient hypotension, this is not of clinical significance. Complications in injection therapy As with any injection, bleeding and bruising may occur. This is seldom a troublesome problem, although if a large haematoma develops, the patients should not inject again until it resolves. Pain may occur after injection, not from the needle but as a result of the local effect of the drug.
Priapism is a complication of injectable agents, but occurs more frequently when papaverine is used.
Providing the patient sticks to the dose which has been determined for him in the clinic, priapism should not occur after the initial dose of the drug has been given. Priapism is dangerous as it can result in penile fibrosis if not treated promptly, and patients should always be told to seek urgent medical advice should an erection not subside after six hours. Most priapisms can be treated by injection into the penis of a vaso-constrictor such as pseudoephedrine. Initially, however, it may be worth trying oral decongestant preparations containing pseudoephedrine. Penile fibrosis is the side-effect which has given most cause for concern.