While pills for ED are convenient, some men sustain stronger erections by injecting medication directly into the penis. Drugs approved for this purpose work by widening the blood vessels, causing the penis to become engorged with blood. Another option is inserting a medicated pellet into the urethra. The pellet can trigger an erection within 10 minutes.
Patients who use this therapy should be trained under the guidance of a urologist, and sterile technique must be used. The drugs must be injected into the shaft of the penis and into one of the penile erectile bodies (corpus cavernosum) 10–15 min before intercourse. Most patients do not complain of pain upon injection. Sexual stimulation is not required, and resulting erections may last for hours. Side effects include penile pain and priapism. The cost is about $12–20 per injection.
PDE 5 inhibitors are broken down primarily by enzyme, cytochrome P450enzyme CYP3A4. Medications that decrease or increase the activity of CYP3A4 may affect levels and effectiveness of PDE 5 inhibitors. Such drugs include medications for the treatment of HIV (protease inhibitors) and the antifungal medications ketoconazole and itraconazole. Thus caution is recommended.
Unconventional CV risk factors, such as impaired erections during masturbation and reduced flaccid acceleration, are interesting parameters to implement in Sexual Medicine context, because they can help fill the gap of information on CV risk, left by the conventional risk factors (the so-called residual risk) (38). However, it should be recognized that not all the healthcare professionals who deal with the complaint of ED (i.e., general practitioners, diabetologists, cardiologists, sport physicians, nurses, etc.) have the facilities or competence for the specific assessment of these parameters. In contexts different than Sexual Medicine and Andrology, the assessment of conventional risk factors is certainly more convenient. Metabolic syndrome (MetS) represents a cluster of metabolic derangements easily and commonly evaluated in several different medical contexts. In a population of more than 600 subjects attending the Sexual Medicine and Andrology Unit of the University of Florence for ED, the presence of MetS was associated with an increased incidence of MACE during 4.3 years of follow-up in younger (first tertile of age: 18–52 years) (Figure 3, Panel A and B) but not in middle aged and older men (second and third tertiles of age: 53–60 and 61–88 years, respectively) (Figure 3, Panel B). Similar to MetS, the algorithms for estimating the risk of developing MACE are easily computed and they take into account factors largely available in a clinical setting. In Europe, the most commonly used algorithm is the SCORE, which takes into account age, smoking habits, systolic blood pressure and total cholesterol (26). These parameters are introduced in a calculation tool that returns the 10-year risk of developing the first MACE. The same estimated risk rate can obviously be derived from different combinations and extent of the single risk factors and, as aforementioned, age has a heavy weight in the amount of risk, even when the other parameters are normal. For overcoming this overestimation, the concept of vascular age, based on the predicted CV risk, has been introduced. Vascular age of a subjects with a specific CV risk profile corresponds to the chronological age of a subjects who has the same estimated risk but only due to chronological age, because of the absence of the other modifiable risk factors (i.e., a non-smoker, normotensive and normocholesterolemic subject) (39,40). Vascular age carries the advantage of easily and directly communicating the concept of high relative risk to patients, in particular to younger ones, who are by definition at low absolute risk (“Your CV risk is the same of a man that is 15 years older than you”). Based on this interesting and useful concept of vascular age, we recently studied the clinical consequences of having a high discrepancy between the estimated vascular and the actual chronological age in our population of men consulting for ED. In our sample, a greater difference between vascular and chronological age was associated with higher glucose and triglyceride levels as well as with impaired penile colour Doppler ultrasound parameters, suggesting a CV impairment (41). When evaluating the subset of men for whom information on incident MACE during a mean follow-up of 4.3 years was available, a greater difference between vascular and chronological age was associated with the incidence of MACE in younger, but not in older men (42).

Nonsustained erection with detumescence after penetration is most commonly caused by anxiety or the vascular steel syndrome. In the vascular steel syndrome, blood is diverted from the engorged corpora cavernosae to accommodate the oxygen requirements of the thrusting pelvis. Questions should be asked regarding the presence or absence of nocturnal or morning erections and the ability to masturbate. Complete loss of nocturnal erections and the ability to masturbate are signs of neurological or vascular disease. It is important to remember that sexual desire is not lost with ED—only the ability to act on those emotions.

All the above subjects were assessed for the prevalence of one or more sexual dysfunction experienced over the past 12 months using a sexual dysfunction checklist (Appendix A) by a trained psychiatrist (BSA). The checklist contains items corresponding to 12 areas of sexual dysfunction described in the Diagnostic Criteria for Research, ICD-10 Classification of Mental and Behavioural Disorders.[15] This was necessary as the SCAN does not contain a detailed assessment for the ICD-10 section on Sexual dysfunction not caused by organic disorder or disease (F52). The disorders specifically tapped by the checklist were aversion towards sex, low sexual desire, difficulty in achieving and in maintaining erection, premature ejaculation, inhibited or delayed ejaculation orgasm with flaccid penis, anorgasmia, pain at the time of coitus, dissatisfaction with frequency of intercourse per week (in the last year and in a representative week 5 years earlier), partner and, own sexual function.
Once observed that the organic component of ED is the most important one in younger patients (Figure 2), the summarized evidence underlines that metabolic and CV risk must not be underestimated in younger men even when they are apparently healthy. In fact, it is particularly in these men that recognizing the presence of risk factors can help in changing life-style, thus really changing the natural history of metabolic and CV diseases. In older men the damage is often already established and the identification of further risk factors usually does not add information to the estimation of CV risk. ED is a symptom that can provide a chance for both the patients and physicians to unearth the presence of CV risk factors and improve both the quality and length of life of these men.
• Blood Vessels: Diabetes damages blood vessels, especially the smallest blood vessels such as those in the penis. Diabetes can also cause heart disease and other circulatory problems. Proper blood flow is absolutely crucial to achieving erection. “Erection is a hydraulic phenomenon that occurs involuntarily,” says Arturo Rolla, MD, of Harvard University School of Medicine. “Nobody can will an erection!” Anything that limits or impairs blood flow can interfere with the ability to achieve an erection, no matter how strong one’s sexual desire.
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