6.4. Intracavernous self-injection of prostaglandin E1 in the treatment of erectile dysfunction (III)

One of the most significant improvements in the treatment of erectile dysfunction took place in 1982, when intracavernosal injection therapy was introduced (Andersson et al. 1991). Most of the impotent patients (70–90%) can be treated by intracavernosal agents (Stackl et al. 1988, Schramek et al. 1989, Ravnik-Oblak et al. 1990). The most common vasoactive agent nowadays is PGE1 (Gerber 1991). Its effectiveness and safety have been proved in several studies (Stackl et al. 1988, Ravnik-Oblat et al. 1990, Hwang et al. 1991). Prolonged pain immediately after the injection has been described with PGE1 (Ravnik-Oblak et al. 1990). There are very few local complications, such as indurations and fibrosis, during long-term use.

The patients were followed up for three years after starting the ICI program. The mean coital frequency with ICI therapy was quite low, 2.8 times per month. Most of the patients did not have problems with giving injection themselves even in the beginning (84.1%). The mean dose of PGE1 used at home was 17.5 micrograms. The most frequently used dose of PGE1 is 20 µg (Stackl et al. 1988, Hwang et al. 1989, Ravnik-Oblak et al. 1990). Erection began within a normal time (9.4 minutes), and its duration was about one hour, which is less than reported previously (Stackl et al. 1988, Ravnik-Oblak et al. 1990, Hwang et al. 1991).

Almost all attemps at intercourse succeeded with PGE1 at home. When measured with Rigiscan at the office, the home dose of PGE1 showed the erection to be fairly good (mean maximal rigidity 53.3% at the base and 56.6% at the tip of the penis). When the patients themselves evaluated the rigidity of the penis in the ICI test situation compared to that at home, the majority did not have equally good erection at the office (52.6%) as at home. This can be explained by sympathoconia or adrenergic constrictor tone due to anxiety (Buvat et al. 1986).

There were no systemic side-effects with PGE1. 7.2% of patients had prolonged pain after the injection, leading to discontinuation by 5.8% of the patients. This is less than in most of other studies where PGE1 has been used alone. When PGE1 is used in combination with other drugs, the incidence of pain could be less (Stackl et al. 1988, Gerber & Levine 1991, Schramek et al. 1994). Priapism occurred in only 3 cases at the beginning of the treatment, but after finding the right dose, no more problems occurred. Priapism used to be a relatively common complication in papaverine users, but after the introduction of PGE1 treatment it has been become rare (Fouda et al. 1989, Hasmat et al. 1991).

Fibrosis was seen in 5.8% of the patients using PGE1 for three years. It led to discontinuation of the drug in 4.3% of the cases. The fibrosis or nodules were small, their mean size being less than 2 cm. In the literature, papaverine users have been reported to have penile scarring and fibrosis more often than PGE1 users (Chen et al. 1994, Hwang et al. 1991).

Many studies have reported improvement of spontaneous erections in men using intracavernous injections (Gerber & Levine 1991, Virag et al. 1991, McMahon 1992, Sharlip 1997). In our study, 34.8% of the patients reported improvement of their own erections after PGE1 therapy. 11.6% of the patients discontinued the ICI therapy for this reason and majority of those patients had a psychogenic etiology. High amount of psychogenic etiology may be one reason for the high dropout percentage up to 49% in some studies (Sister 1990, Gerber & Levine 1991, Govier et al. 1993, Fallon 1995).

The main reasons why many patients do not continue their PGE1 therapy in the long run include the fact that their own erections improve or that there are changes in their life situation. At the baseline, precise determination of the home dose of PGE1 and instruction with the technique are important for treatment acceptance.