Studies on intracavernosal VIP levels during pharmacologically induced penile erections

Intracavernosal and peripheral venous vasoactive intestinal polypeptide (VIP) levels were measured in men with predominantly organic or predominantly psychogenic impotence. The measurements were taken at intervals up to 30 min following intracavernosal injections of saline, papaverine hydrochloride and papaverine hydrochloride and phentolamine. Levels were also measured after tactile and visual sexual stimulation and following an intravenous injection of papaverine and phentolamine. A penile erection occurred in all men receiving intracavernosal vasoactive compounds. The mean VIP concentration did not alter significantly in either cavernosal or peripheral venous blood during the erection. Mean VIP concentrations were significantly greater in the neurogenic (all diabetic) group than in the other groups studied. Mean cavernosal and peripheral VIP concentrations did not alter following tactile or visual sexual stimulation and no significant alteration in mean peripheral venous VIP concentration occurred following injection of papaverine and phentolamine. The putative role of VIP in the induction of penile erection has not been elucidated in these studies.     

勃起功能障碍病人阴茎海绵体血浆中降钙素基因相关肽含量的研究

目的　了解阴茎勃起前后 ,阴茎海绵体内血浆中降钙素基因相关肽 (CGRP)含量。方法　对不同组受检者行海绵体内注射生理盐水、盐酸罂粟碱、盐酸罂粟碱和酚妥拉明混合液。每次注药间隔时间超过 3 0分钟 ,注药前后取海绵体内血液测定CGRP含量。结果　正常人及各类ED在海绵体内注射血管活性药物后阴茎均发生勃起。在阴茎勃起过程中海绵体内血浆CGRP含量升高 (P <0 .0 5 )。周围静脉注射罂粟碱和酚妥拉明混合液的受检者 ,注药后周围静脉血浆CGRP含量无变化 (P >0 .0 5 )。结论　CGRP是参与人类阴茎勃起的重要神经递质     

Alpha-adrenergic receptor blockade by phentolamine increases the efficacy of vasodilators in penile corpus cavernosum

Penile trabecular smooth muscle tone, a major determinant of erectile function, is highly regulated by numerous inter- and intracellular pathways. The interaction between pathways mediating contraction and relaxation has not been studied in detail. To this end, we investigated the functional effects of alpha adrenergic receptor blockade with phentolamine and its interaction with vasodilators (sildenafil, vasoactive intestinal polypeptide (VIP) and PGE1) that elevate cyclic nucleotides on penile cavernosal smooth muscle contractility. In organ bath preparations of cavernosal tissue strips contracted with phenylephrine, phentolamine significantly enhanced relaxation induced by sildenafil, VIP and PGE1. Sildenafil, VIP or PGE1 also significantly enhanced relaxation induced by phentolamine in cavernosal tissue strips contracted with phenylephrine. To study the effects of alpha adrenergic receptor blockade and modification of cyclic nucleotide metabolism during active neurogenic input, cavernosal tissue strips in organ bath preparations were contracted with the non-adrenergic agonist endothelin-1 and subjected to electrical field stimulation (EFS) in the absence or presence of phentolamine and/or sildenafil. EFS (5-40Hz) typically caused biphasic relaxation and contraction responses. Phentolamine alone enhanced relaxation and reduced or prevented contraction to EFS. Sildenafil enhanced relaxation to EFS at lower frequencies (< or = 5 Hz). The combination of phentolamine and sildenafil enhanced EFS-induced relaxation at all frequencies tested. EFS, in the presence of 10 nM phentolamine and 30 nM sildenafil, produced enhanced relaxation responses which were quantitatively similar to those obtained in the presence of 50 nM sildenafil alone. Thus, blockade of alpha-adrenergic receptors with phentolamine increases the efficacy of cyclic nucleotide-dependent vasodilators. Furthermore, phentolamine potentiates relaxation and attenuates contraction in response to endogenous neurotransmitters which are released during EFS. These findings suggest that antagonism of alpha-adrenergic signaling enables other independent relaxatory pathways to predominate within penile trabecular smooth muscle.     

Penile response to intracavernosal vasoactive intestinal polypeptide alone and in combination with other vasoactive agents

Intracavernosally injected vasoactive intestinal polypeptide (VIP) (2 micrograms and 4 micrograms) resulted in penile tumescence even in men with predominantly organic impotence. Papaverine and phentolamine were successful in inducing erections in all subjects studied but the addition of VIP to this combination improved the erectile response further. A combination of papaverine and VIP produced penile rigidity similar to that with papaverine and phentolamine. While intracavernosal VIP alone produced disappointing penile responses, its combination with papaverine potentiated the response to this drug, probably by increasing venous outflow resistance.     

Comparison of oral and intracavernosal vasoactive agents in penile erection

This discussion summarizes the potential differences in physiologically and pharmacologically induced erections and highlights the possible differences in the pathways facilitated by oral versus intracavernosal agents in penile erection. Oral agents act in conjunction with sexual stimulation either increasing corporal smooth muscle relaxation or attenuating smooth muscle contraction. However, their efficacy is dependent on sexual stimulation. Intracavernosal administration of phosphodiesterase type 5 inhibitor (sildenafil) or short-acting alpha adrenergic receptor antagonist (phentolamine), in the absence of sexual stimulation, does not initiate penile erection. In contrast, intracavernosal administration of PGE1 or papaverine induces erection independent of sexual stimulation. Thus, oral agents are not direct mediators of smooth muscle relaxation and act to facilitate relaxation in response to sexual stimulation, while intracavernosal agents directly mediate smooth muscle relaxation, independent of sexual stimulation. Although, considerable advances have been made in elucidating the physiology and pharmacology of erectile function, details of the signal transduction pathways affected by these agents in the penile corpus cavernosum are yet to be fully investigated. International Journal of Impotence Research (2000) 12, Suppl 1, S81-S88     

In vitro viability of human cavernosal endothelial and fibroblastic cells after exposure to papaverine/phentolamine and prostaglandin E1

OBJECTIVE: To investigate the influence of commercially available vasoactive drugs on human cavernosal endothelial and fibroblastic cells in vitro, as although corporal fibrosis is a well known side-effect of intracavernosal injection therapy for erectile dysfunction, the possible detrimental effect of these agents on the endothelium lining the cavernosal vascular spaces is uncertain. MATERIALS AND METHODS: Cultured primary endothelial (13) and fibroblastic cells (12), obtained from potent patients undergoing penile surgery, were exposed to different physiological dilutions of prostaglandin E1 (PGE1), papaverine/phentolamine or the respective triple-mix of these agents for 30 min. Viable cells were counted and cell metabolic activity measured in these cultures 48 h after drug exposure. RESULTS: There was a significant dose-dependent decrease in the viable cell count after exposure to papaverine-containing formulations, probably because of the low pH of this substance. This cytotoxic effect was more pronounced in endothelial than in fibroblastic cells, and was not apparent in the PGE1 groups. The relative increase in cell metabolic activity in cultures affected by a moderate cytotoxic effect indicated a regenerative process. CONCLUSION: These comparative results in endothelial and fibroblastic cell cultures suggest that the endothelium rather than the interstitium of the corpus cavernosum is more sensitive to side-effects produced by intracavernosal injection therapy with papaverine. Thus, unfavourable consequences on the function of the endothelial layer might be as important as the risk of interstitial fibrosis. As these effects were not detected for PGE1 this drug should be preferred to papaverine in clinical practice.     

Intracavernosal sildenafil facilitates penile erection independent of the nitric oxide pathway.

Sildenafil, in nanomolar serum levels, is an effective phosphodiesterase type 5 inhibitor, and facilitates penile erection only during sexual stimulation. However, there is limited information on the pharmacological activity of this agent when tissue levels approach millimolar concentrations following intracavernosal injection. The aim of this study was to investigate whether sildenafil causes penile erection in the absence of active neurogenic input. Organ bath preparations of rabbit penile cavernosal tissue strips were contracted with 1 microM phenylephrine and exposed to increasing concentrations of sildenafil in the absence or presence of the nitric oxide (NO) synthase inhibitor, Nomega-nitro-L-arginine methyl ester (L-NAME; 0.6 mM). Sildenafil caused dose-dependent relaxation of rabbit cavernosal smooth muscle at high concentrations (>0.1 microM) with little or no effect at concentrations below 0.1 microM. The addition of L-NAME did not affect this response. In a separate protocol, sildenafil dose response determinations were performed in the presence of the guanylyl cyclase inhibitor, 1H-[1,2,4]-oxadiazolo-[4,3-a]-quinoxalin-1-one (ODQ; 3 microM) or vehicle (50% dimethyl sulfoxide [DMSO]). Relaxation to sildenafil in the presence of DMSO was significantly enhanced relative to sildenafil alone. ODQ treatment partially attenuated relaxation to sildenafil, but failed to completely inhibit the response. In cavernosal tissue strips, sildenafil elevated basal cyclic guanosine monophosphate (cGMP) levels twofold (0.54 vs. 1.10 pmol/mg prot). To further investigate these observations, anesthetized rabbits were injected intracavernosally with sildenafil (0.3-1.3 mg). In the absence of pelvic nerve stimulation, the magnitude and duration of the intracavernosal pressure increased in a dose-dependent fashion in response to sildenafil, approaching the systemic arterial pressure at higher doses. Intracavernosal administration of L-NAME, at doses that inhibited pelvic nerve stimulated penile erection, did not alter the response to intracavernosal sildenafil at 1.3 mg. Sildenafil, at the doses tested, did not significantly change the systemic arterial pressure. These data suggest that intracavernosal sildenafil, at tissue levels approaching millimolar concentrations, can cause relaxation of vascular smooth muscle and penile erection by a novel mechanism independent of the classical NO/cGMP pathway.     

Effects of intracavernosal trazodone hydrochloride: animal and human studies

Trazodone hydrochloride is an oral antidepressant agent which has been associated with the improvement of erections in impotent men and the development of prolonged erections or priapism in potent men. An in vivo study in animal and human subjects was performed to gain experience with the effect of intracavernosal trazodone. In the anesthetized New Zealand White rabbit, intracavernosal trazodone or its major metabolite m-chlorophenylpiperazine (m-CPP) produced full penile erection in 76% and 84% of animals studied respectively with doses ranging from one to 15 mg. On the other hand, intracavernosal administration of five mg. papaverine resulted in a prolonged erection in 90% of animals studied. In 13 selected volunteer patients, intracavernosal trazodone caused tumescence but not full penile erection with corporal body pressures of 28.2 +/- 5.8 mm. Hg. Intracavernosal papaverine or papaverine and phentolamine in these subjects resulted in significantly higher corporal body pressures of 58 +/- 18 mm. Hg (p less than .05). Intracavernosal administration of alpha adrenoceptor agonists but not normal saline resulted in complete detumescence of trazodone- or m-CPP-induced prolonged erection in the animal studies. Intracavernosal trazodone results in erectile activity that appears in part based on its local alpha blocking activity but like other intracavernosal alpha-blocking agents is not as effective in initiating penile erections as are intracavernosal agents that directly induce smooth muscle relaxation.     

Comparison of the synergistic effects of tamsulosin versus phentolamine on penile erection: in vitro and in vivo studies

In vitro and in vivo studies were performed to determine the potential use of tamsulosin (TAM) versus phentolamine (PHE) for intracavernosal injection (ICI) therapy when mixed with papaverine (PAP) and/or prostagladin E₁ (PGE₁) or with vasoactive intestinal polypeptide (VIP) for the treatment of erectile dysfunction. We performed isometric tension studies on rabbit (n=15), dog (n=5), and human (n=10) cavernous smooth muscle strips with TAM, PAP, PHE, VIP, PGE₁, and the combinations of PAP and PHE; PAP and TAM; VIP and PHE; VIP and TAM; PAP, PGE₁ and PHE; and PAP, PGE₁ and TAM. TAM-containing trimix (PAP 18.75 mg, PGE₁ 6.25 μmg, and TAM 0.875 mg per ml) or PHE-containing trimix (PAP, PGE₁, and PHE 0.625 mg per ml) were also injected into the cavernous bodies of ten mongrel dogs. Among the single agents, TAM and PGE₁ (only in human) had the strongest effect on the relaxation of cavernous muscles in rabbit, dog, and human strips (P < 0.05). Relaxation responses to 2- or 3-drug mixtures containing tamsulosin were also significantly better (P < 0.05) than PHE-containing ones in rabbit, dog, and human strips. The increase in intracavernosal pressure with a TAM-containing trimix was higher than with a PHE-containing one (0.03 ml; 81.2 vs 75.8 mmHg, 0.04 ml; 103.2 vs 94.3 mmHg), although not statistically different. The drop in systemic blood pressure was lower after injection of a TAM-containing trimix than a PHE-containing one, although not statistically different. In conclusion, tamsulosin might be a more efficacious and safer agent to use for ICI therapy than phentolamine. Received: 9 February 1999 / Accepted: 25 June 1999     

Prostaglandin E1 in erectile dysfunction

Of 447 presenting with erectile dysfunction, 322 (72%) responded to intracavernous injection of PGE1 with erections that were adequate for sexual intercourse. A multidisciplinary comparative study of PGE1 and other vasoactive drugs, e.g., papaverine or the combination of papaverine and phentolamine, was performed in 249 patients. Whereas 180 of the 249 patients (72.3%) showed adequate erections after 10 or 20 micrograms PGE1, only 79 of them (31.3%) did so after papaverine. A further 72 of the 249 patients (29%) had adequate erections after papaverine/phentolamine; thus, a total of 151 of 249 patients (60.3%) developed good erections after papaverine/phentolamine. Whereas after PGE1 no patients at all suffered from priapism lasting more than 6 h, this occurred in 13 of 249 patients (5.2%) after papaverine or papaverine/phentolamine. After intracavernous injection of PGE1, 9.4% of the patients complained of uncomfortable penile sensations during erection interfering with sexual intercourse. Since the initial study, 60 patients have been instructed in self-injection therapy and a further 45 patients obtain intracavernous PGE1 injections periodically, with very promising results. In vitro studies of cavernosal tissue samples obtained from potent men with penile deviations showed both the excellent relaxation of the smooth muscles of cavernous bodies by PGE1 and the antiadrenergic effect of the drug.     

Pharmaco-induced erections for penile color-duplex ultrasound: oral PDE5 inhibitors or intracavernosal injection?

To prospectively compare the clinical responses and penile color-duplex ultrasound (PCDU) results of oral PDE5 inhibitors (PDE5-Is) with papaverine intracavernosal injection (ICI) and to evaluate whether PDE5-Is could be used as alternatives to vasoactive agent injections, 25 ED patients underwent PCDU three times with an interval of at least 1 week, using different pharmacological induction: ICI mode (30-60?mg papaverine), sildenafil mode (100?mg sildenafil) and tadalafil mode (20?mg tadalafil). The preference of the patients was collected when all tests were completed. No significant differences were found in peak systolic velocity and acceleration time among all three modes. However for the ICI mode, end diastolic velocity of the right cavernosal artery was significantly higher than those of the sildenafil and tadalafil modes 5?min after erection induction, and at 15?min it became lower than those of two PDE5-I modes. Consequently, resistance index of the right cavernosal artery in ICI mode was reversed at 5 and 15?min. In all, 60.0 and 56.0% patients managed to reach full erection in PDE5-Is modes, which was significantly lower than in ICI mode (80.0%). Therefore, although PDE5-Is and papaverine ICI showed similar effects on PCDU parameters in detecting arterial ED, more patients had better clinical responses to ICI, and oral PDE5-Is administration still showed some pitfalls in practical use.     

Preference for oral sildenafil or intracavernosal injection in patients with erectile dysfunction already using intracavernosal injection for > 1 year

Authors from Seoul describe their experience with patients already on triple therapy by intracavernosal injection who changed to oral sildenafil. Rather surprisingly, they found that patients had had a greater preference than expected for triple therapy, feeling that they had a better quality of erection on intracavernosal injection. The subject of the effect of renal transplantation on sperm quality and sex hormone levels is discussed by authors from Teheran. They found that sperm morphology and density remained unchanged, but there were significant improvements in sperm mobility. There was also an improvement in hormone levels and sexual function. OBJECTIVE: To investigate the efficacy and preference for oral sildenafil or intracavernosal injection (ICI) therapy in patients with erectile dysfunction (ED) already using ICI. PATIENTS AND METHODS: In all, 69 patients with ED (mean age 55.1 years, sd 12.3) on ICI therapy with triple solution (papaverine/phentolamine/prostaglandin-E1) for > 1 year were recruited for the study. Their erection quality, adverse reactions and selection rate of oral sildenafil or ICI as treatment, after using sildenafil for 3 months, and the reasons for their preferences, were compared between the regimens, RESULTS: Overall, 52 men (75%) responded to sildenafil; of these men, the erection quality with ICI was better than that with sildenafil in 46 (89%) and 16 (31%) preferred ICI as their treatment. Eighteen patients (35%) used each treatment alternately and 18 (35%) used sildenafil exclusively. The main reason given by patients for choosing ICI was a better quality of erection (74%). CONCLUSION: More patients with ED and using ICI preferred it as their main treatment than was expected, even though they had a good response to oral sildenafil. A better quality of erection with ICI was the reason why experienced patients chose this method, differing from the choice of patients starting treatment for ED.     

Why a combined intracavernosal injection with trimix and oral sildenafil is reliable therapy in the ultrasonographic evaluation of erectile dysfunction

OBJECTIVE

To evaluate prospectively and compare the clinical response and the change in nucleotides correlating with haemodynamic changes in the cavernosal arteries after an intracavernosal injection (ICI) with vasoactive agents with or without oral sildenafil in men with erectile dysfunction (ED).

PATIENTS AND METHODS

In all, 80 patients with ED were prospectively evaluated by clinical assessments, measuring nucleotides in blood plasma and haemodynamics in cavernosal arteries. All patients had colour Doppler ultrasonography (CDU) twice with an interval of 5 h. First, each patient had CDU after ICI with trimix (0.25 mL) or prostaglandin E1 (PGE1, 5 µg), and the second CDU was after ICI trimix given 1 h after oral placebo (group I), sildenafil 25 mg (group II) or 100 mg (group III) and after ICI with PGE1 at 1 h after oral placebo (group IV) or 100 mg sildenafil (group V). Levels of cGMP and cAMP in peripheral venous and penile cavernosal blood plasma were measured at 15 min after ICI.

RESULTS

The mean peak systolic velocity (PSV) at 5, 10, 15 min, and resistive index at 10 min in the second CDU after ICI with trimix, were significantly increased in group III. The mean (sem ) levels of cavernosal cGMP were significantly increased in group III and V, from 1130.1 (313.5) to 2056.7 (580.4) and 1017.0 (214.2) to 1905.2 (915.0) fmol/mL, respectively. cAMP was significantly increased in group V, from 9533.1 (2068.4) to 12150 (3684.2) fmol/mL.

CONCLUSIONS

The haemodynamic changes and cGMP and cAMP production in the cavernosum were improved by trimix plus sildenafil more than with than PGE1 plus sildenafil or one ICI with trimix or PGE1. The results suggest that ICI with trimix and sildenafil is the best combination for a pharmacological erection test.     

Involvement of alpha-receptors and potassium channels in the mechanism of action of sildenafil citrate

Modulation of the adrenergic activity and interfering with channels such as potassium channels may affect relaxation and contraction of the corpus cavernosum. Sildenafil is a selective phosphodiesterase-5 inhibitor, proven effective in treating erectile dysfunction.In this study, the effect of sildenafil citrate on alpha-receptors modulation and potassium channels was tested. The direct relaxant effect of sildenafil citrate was studied by measuring changes in isometric tension in isolated strips of rabbit corpus cavernosum and rat aortic ring precontracted with phenylephrine or KCl compared to that of diazoxide in the presence and absence of tetraethylammonium. The inhibitory effect of sildenafil on electrical field stimulation-induced contraction of rabbit corpus cavernosum and rat anococcygeus muscle was also studied compared to that of phentolamine. Muscle relaxant effect of sildenafil (1 x 10(-9)-1 x 10(-6) M on phenylephrine-precontracted rabbit corpus cavernosum strips was not attenuated by N(G)-nitro-L-arginine (3 x 10(-5) M). Cumulative addition of sildenafil (1 x 10(-9)-1 x 10(-6) M) and phentolamine (1 x 10(-9)-1 x 10(-6) M) to the organ bath dose-dependently inhibited electrical field stimulation-induced contraction of rabbit corpus cavernosum and rat anococcygeus muscle, with almost similar EC(50) values. Sildenafil (1 x 10(-7) M) also inhibited phenylephrine-induced contraction of rat aortic rings by 39.83+/-3.01%. In addition, tetraethylammonium (1 x 10(-3) M) significantly attenuated the muscle relaxant effect of sildenafil (1 x 10(-9)-1 x 10(-6) M) on phenylephrine-precontracted strips of rabbit corpus cavernosum.Sildenafil citrate is capable of producing cavernosal smooth muscle relaxation by an additional mechanism that may involve alpha-receptors and potassium channel opening.     

Objective double-blind evaluation of erectile function with intracorporeal papaverine in combination with phentolamine and/or prostaglandin E1.

We performed a double-blind, crossover study using objective measurements to compare maximum rigidity and duration of erections with papaverine hydrochloride in combination with phentolamine mesylate and/or prostaglandin E1. The rationale for the protocol was to combine a smooth muscle relaxant (papaverine) with either or both vasodilating agents (phentolamine and prostaglandin E1) commonly used for injection therapy. The 7 volunteer patients with organic impotence documented by abnormal nocturnal penile tumescence testing were injected with 0.5 to 1.0 ml. papaverine (30 mg./ml.) in combination with phentolamine (0.5 mg./ml.) and/or prostaglandin E1 (5 micrograms./ml.). Each patient received 2 injections on each of 2 testing dates; injection 2 was given after tumescence resulting from injection 1 had subsided completely. The medications were given in a randomized, counterbalanced order following double-blind procedures. Patients evaluated the erections subjectively. In addition, the RigiScan device was used to measure maximum rigidity and duration of erections. All patients observed increased duration of erections with both combinations containing prostaglandin E1. Analysis of RigiScan measurements showed no statistically significant differences for maximum rigidity (p greater than 0.1) but significantly greater duration of erections with papaverine plus prostaglandin E1, and papaverine plus phentolamine plus prostaglandin E1 compared to papaverine plus phentolamine (p less than 0.001). There was no statistical difference in rigidity or duration of erections between papaverine plus prostaglandin E1 and papaverine plus phentolamine plus prostaglandin E1. No patient reported significant penile pain with any of the injections. We conclude that the combination of papaverine and prostaglandin E1 produces erections of longer duration than papaverine plus phentolamine and that no additional benefit is gained by adding phentolamine to a combination of papaverine and prostaglandin E1. Further studies are in progress to define optimal dose response curves for papaverine and prostaglandin E1 as individual agents and in combination.     

Priapism induced by intracavernosal vasoactive intestinal polypeptide and phentolamine mesylate

This is a case of priapism (21 h) following an intracavernosal injection of vasoactive intestinal polypeptide (VIP) 25 mcg with phentolamine mesylate (PM) 1 mg responding to venesection and intracavernosal injection of 1 mg metaraminol.     

Relaxation effects of adrenomedullin in isolated rabbit corpus cavernosum smooth muscle

OBJECTIVES: To clarify the pharmacological effects of adrenomedullin, a potent vasodilator and hypotensive peptide isolated from human phaeochromocytoma cells, on corpus cavernosal smooth muscle in vitro, as the intracavernosal injection of adrenomedullin induces penile erection in the anaesthetized cat. MATERIALS AND METHODS: The effects of adrenomedullin were investigated in isolated muscle strips from New Zealand rabbit corpus cavernosum smooth muscle pre-contracted with phenylephrine alone, in the presence of indomethacin (cyclooxygenase inhibitor), Nomega-nitro l-arginine methyl ester (L-NAME, a nitric oxide synthase inhibitor), and K+-channel blockers. RESULTS: Adrenomedullin caused relaxation of isolated pre-contracted rabbit corpus cavernosum strips in a concentration-dependent manner. The response of corpus cavernosum was unaffected L-NAME, indomethacin and K+-channel blockers. CONCLUSION: The relaxation exerted by adrenomedullin in rabbit corporal tissue may arise from the effect of the drug on its specific receptors and/or calcitonin gene-related peptide-1 receptors. The relaxant effect of adrenomedullin might lead to novel clinical applications for erectile dysfunction.     

Erectile dysfunction after kidney transplantation: our 22 years of experience

AIM: To evaluate the results of treatment of erectile dysfunction (ED) in kidney transplant recipients before and after the advent of sildenafil. MATERIALS AND METHODS: From 1981 through 2002, 971 male patients of mean age 53.4 years received a renal graft. Erectile dysfunction (ED) was investigated in all patients at the first urologic visit posttransplantation. Psycho-sexual support was offered to all patients. Before sildenafil use (1998), our diagnostic approach was complex. From 1998 we tested: serum levels of testosterone, prolactin, and glucose with penile duplex ultrasonography and NPT reserved for selected cases. RESULTS: From 1981 through 1998, 365 male kidney transplant recipients (45%) reported ED. Only 169 patients chose to be treated: 27 responded to psycho-sexual therapy; 3 received testosterone with benefit; 133 had a good results from intracavernosal injection of vasoactive drugs; and 6 received a penile prosthesis. Since 1998, 126 patients reported ED (78.3%). Only 78 chose treatment: 24 patients had a satisfactory response to sildenafil (65% with 50 mg and 35% with 100 mg). PGE1 alone or in combination with papaverine and phentolamine produced a good response in 37 patients; 17 patients did not respond to pharmacotherapy; and 5 received a tricomponent penile prosthesis without complications. The side effects of sildenafil and PGE1 therapy were similar to those reported in the literature. CONCLUSIONS: ED is an important problem in male renal transplant recipients. Cultural resistance to treatment is common. However, treatment with sildenafil citrate and intracavernosal self-injection of PGE1 are well accepted, and prosthetic devices may help in resistant cases.     

Intracavernosal therapy and vacuum devices to treat erectile dysfunction

OBJECTIVE: To explore the mechanism of action, as well as the risks and benefits of two popular and effective treatment modalities for erectile dysfunction (ED). Intracavernosal injection (ICI) therapy involves direct injection of vasoactive agents into cavernosal tissue to facilitate erection. Commonly perscribed agents include PGE1 (alprostadil), papaverine, and phentolamine. Though there are some risks associated with improper injection technique, these agents have a low side effect profile and have proven to be very effective, especially in combination. Patients may also chose the less invasive option of a vacuum erection device (VED), which are often successful in ED of any etiology.     

Intracavernous pharmacotherapy

Summary Intracavernous application of vasoactive substances not only has enhanced our understanding of penile hemodynamics, the physiology of penile erection, and the pathophysiology of erectile dysfunction but also has revolutionized the diagnosis and treatment of erectile dysfunction in the last 15 years. Virag was the first to report on the erectile effect of papaverine in humans, and Brindley later reported the effect of intracavernous application of alpha-receptor-blocking agents on cavernous tissue. These reports led to numerous basic and clinical investigations and ultimately established a new treatment alternative for patients with erectile dysfunction that is now considered to be the treatment of choice for most patients. Changes in penile hemodynamics include the relaxation of cavernous smooth musculature and arteries, which leads to an increase in arterial blood flow and a restriction of venous outflow through a compression of subtunical veins. These hemodynamic changes are the prerequisite for the induction and maintenance of penile erection. With the intracavernous application of vasoactive substances it was possible to influence penile hemodynamics at a local level and to induce an erection despite alterations in the nervous system, penile arterial blood flow, cavernous musculature, or neurotransmitter status. In addition, the localapplication of pharmacologically active substances directly to the end organ enabled the achievement of high local drug concentrations without severe systemic side effects. The commonly used substances are papaverine, the combination of papaverine and phentolamine, and prostaglandin E1 (alprostadil). In addition to these established substances, several other regimens, such as linsidomine (SIN-1), calcitonin gene-related peptide (CGRP), moxisylyte, and various triple- or quadruple drug mixtures have been described. In addition, several other compounds as well as different routes of administration are on the horizon and may prove to be effective in the future diagnosis and treatment of erectile dysfunction.