Erectile Dysfunction (ED) is the persistent or frequent inability of the penis to achieve and/or maintain an erection sufficient for satisfactory sexual intercourse. The incidence is very high, with approximately 152 million men worldwide suffering from ED in 1995 and an estimated 322 million in 2025. 2000 Massachusetts Men’s Ageing Study (MMAS) showed that the annual incidence of ED in men aged 4O-69 years was 2.6%, with an overall incidence of 44%. Due to the specificity of the condition of different patients, the choice of treatment methods are diverse, there are the first line of psychosexual treatment, oral medication and negative pressure assistive devices; the second line of transurethral drug delivery and intracavernosal drug injection; the third line of prosthesis implantation surgery treatment. In addition, the research of gene therapy has been developed rapidly and has achieved promising results. The erection process is a physiological phenomenon triggered by changes in penile hemodynamics under neurological and endocrine regulation. Nitric oxide (NO) is an important neurotransmitter in this process, which activates guanylate cyclase in the cytoplasm to convert GTP to cGMP, which acts as a second messenger to mediate a series of biochemical reactions, leading to smooth muscle diastole and penile erection. PDE5 inhibitors are similar in structure to cGMP and competitively inhibit the binding of cGMP to PDE5 to inactivate PDE5, reducing cGMP hydrolysis and inducing and enhancing penile erection, a normal physiological process. There are three major PDE5 inhibitors in clinical use, namely sildenafil, vardenafil and tadanafil. Sildenafil is the first oral PDE5 inhibitor registered for use, and its appearance has significantly improved the function of patients to obtain and maintain an erection. A large number of clinical trials have fully confirmed the effectiveness and safety of sildenafil in the treatment of ED, and it has become the drug of choice for most patients, and it is effective for long-term use. In patients who took sildenafil orally for 36 and 52 weeks, the efficiency rate was 92% and 89% respectively. In order to further confirm the efficacy of sildenafil, in recent years, 411 patients with different causes of ED and 71 patients who also suffered from diabetes were studied experimentally, and after taking sildenafil orally for 12 weeks, 69% of the patients had significant improvement in erectile function, while the efficiency of placebo was only 18%. Sildenafil also improved erectile function in patients with refractory diseases such as coronary artery disease, peripheral vascular disease, post-coronary artery bypass grafting, hypertension, spinal cord injury, post-radical prostatectomy, post-transurethral resection of the prostate, etc. Viswaroop et al. compared the experimental efficacy of sildenafil with intracavernosal injection of poppies in the penis and showed that both were equally effective with no significant difference. Vardenafil is also a powerful selective PDE5 inhibitor, and early trials have shown that 10 mg and 20 mg of vardenafil for 12 weeks showed significant improvement in erectile function in 57% and 72% of patients, and 13% of patients given placebo showed improvement. Giuliano et al. concluded that vardenafil is safe and effective in the treatment of spinal cord injury ED. They randomly divided 418 patients with spinal cord injury for more than 6 months into vardenafil-treated and placebo groups. 76% of patients treated with vardenafil achieved satisfactory erection after 12 weeks, 59% could maintain erection, 19 After 12 weeks, 76% of patients treated with vardenafil achieved satisfactory erection, 59% could maintain erection, and 19% could successfully ejaculate, compared with 41%, 22%, and 10% in the placebo group, respectively, with significant differences between the two groups, thus fully confirming the ability of vardenafil to improve erection and ejaculation function. Vardenafil has mild side effects and is well tolerated by patients with spinal cord injury, but the mechanism by which it improves ejaculatory function is unknown. Vardenafil also significantly improved the quality of sexual life and partner satisfaction in patients with ED after prostatectomy. Tadalafil is another new PDE5 inhibitor that is also rapidly absorbed but has a longer duration of action than sildenafil and vardenafil and is not affected by diet, giving a single dose that can effectively last 36 h compared to 6 h for sildenafil. The efficiency of patients reached 20% to 47% with 20mg dose and 72% to 91% with 20mg dose and 20% to 47% with placebo group. Raymond et al [8] reported that tadanafil significantly improved the satisfaction of ED patients, and the trial was divided into 10 mg dose group and 20 mg dose group, and the placebo group was given as a control. The satisfaction rate was 55% and 72% for the mild patients and 33% for the placebo group; 60%, 65% and 19% for the three groups of moderate patients; and 32%, 49% and 9% for the severe patients. Moreover, tadalafil is suitable for patients of all races. Abraham et al [9] treated 1911 patients from 3 different races with 20 mg tadalafil for 12 weeks and confirmed that it was equally effective in patients of different races, with a significant improvement in IIEF-5 scores. It was also well tolerated, with only 2.8% of patients dropping out of treatment due to side effects. 2, other drugs Yohimbine is an indole alkaloid, which was often used as a commonly used oral drug for ED before the advent of PDE5 inhibitors, and was proposed for use by the FDA in 1976. Although it can improve sexual impulse, but this effect has not been clinically proven effective. It also causes an increase in blood pressure and heart rate, and symptoms such as irritability and tremors. Data from only one small study have confirmed effectiveness, and no conclusions can be drawn about its efficacy or safety, so yohimbine is not currently recommended as a drug for ED treatment. Apomorphine is a central agonist that releases large amounts of Oxytocin into the spinal cord by exciting priority areas in the hypothalamus and dopamine receptors in the paraventricular nucleus, thereby causing vasodilation and smooth muscle diastole in the penis. Sublingual apomorphine is widely used as a traditional drug for different types of ED, significantly improving erectile function and increasing the frequency of sexual intercourse. The most effective dose was 3 mg, and increasing the dose did not improve the effect. Data showed that 2 mg, 3 mg and 4 mg of apomorphine achieved satisfactory erections in 33%, 50% and 50.2% of patients in double-blind treatment. In addition, the subcutaneous administration of melanin receptor agonist PT-141 induced erections in 85% of patients with psychogenic or organic ED without any stimulation, compared with only 5% in the placebo group; in patients with mild to moderate ED, the efficiency of oral phentolamine was around 40% to 60%; in patients with combined depression, trazodone hydrochloride had good results. The mechanism of action is to impede the reuptake of 5-hydroxytryptamine by the sexual central nervous system and the blocking effect of sympathetic nerves on the cavernous body of the penis. Testosterone is an important sex hormone in the body, and plays an important role in the regulation of the physiological process of penile erection, as does PDE5, and the expression of nitric oxide synthase (NOS). It is conservatively estimated that approximately 12% of current ED patients have below normal testosterone, and testosterone replacement therapy is effective in such patients, significantly improving sexual function and libido. Testosterone treatment alone can achieve an efficiency rate of 57%. However, due to the specificity of ED pathophysiology, satisfactory results are sometimes not achieved alone, and the combination of sildenafil can significantly improve erectile function. In patients who have not been treated with PDE5 inhibitors, oral treatment with testosterone for 2 weeks, followed by 100 mg of sildenafil when testosterone levels return to normal, can achieve satisfactory erections in 70% of patients. It is worth mentioning that early prostate cancer has been proven to be endocrine hormone dependent, so it is necessary to perform PSA assay, prostate finger examination and, if necessary, prostate biopsy to exclude the possibility of prostate cancer before this treatment is performed [13]. （This type of treatment consists of prostaglandin E1 (PGE1) in the form of pellets, which are inserted into the urethra through the urethral orifice via a MUSE device, with an efficiency of 5O% to 70%. However, market follow-up surveys have shown that its use is unsatisfactory and that about 3% of patients present with hypotension after the first dose. However, it is a non-invasive treatment compared to penile corpus cavernosum injections and can be an option for patients who are not suitable for or have failed to respond to PDE5 inhibitor therapy. Combining it with a negative penile compression device or oral PDE5 inhibitor treatment at the same time is more effective than using it alone. However, the dose and safety need to be further studied. 2, penile corpus cavernosum injection As the first ED treatment modality, it was once considered an epoch-making discovery. Even today, it remains an indispensable option for its safety, efficiency and high satisfaction. Poppers and prostaglandin 1 (PGE1) are the main therapeutic agents, with PGE1 being used in 70% of patients. after radical prostatectomy, ED patients who have failed to respond to sildenafil treatment are treated with penile cavernosal vasoactive drug injections, which are 85% effective. For neurogenic ED its efficacy is better than that of sildenafil, and the efficiency of using penile cavernosal injection after sildenafil treatment is ineffective can reach 88%. It is also a popular choice for diabetic ED patients, with a high safety profile and no reported cases of sustained penile erection to date [14]. The disadvantage of this method is that it is invasive and therefore the chance of abandonment remains high.Perimenis et al [14] followed 38 patients with diabetic ED and found that all initially used penile cavernosal injection therapy due to severe ED, however the number of patients who adhered to it decreased year by year with a mean decrease of 50% over 10 years. Most patients were initially effective on low-dose PGE1 therapy and gradually required higher doses to be effective or progressively required a combination of drugs. Therefore, the key point to achieve satisfactory results is to adjust the dose and the method of injection. Second, the negative pressure penile erection aid This method makes the penis passively engorged with blood, and then the compression ring is placed at the root of the penis to stop the return of blood, so as to maintain the erect state, and was initially used in 1985, and obtained an efficacy of up to 88, 8%. It is a safe and effective option for patients who have failed to respond to oral medication. It has a satisfaction rate of 27% to 74% according to two-year follow-up results. Because it is not a natural filling process, the prescribed maintenance time cannot exceed 30 minutes, so not many patients use this device for a long time, and most of them stop using it after 3 months. A survey to compare the treatment of negative pressure penile erection aid and sildenafil showed that 66.6% of patients chose sildenafil and 33.3% chose the former, but the combination of negative pressure penile erection aid with sildenafil, intraurethral drug delivery or cavernous injection can greatly improve the efficacy. Mulhall reported that after penile prosthesis implantation, the satisfaction rate and quality of life of patients and their sexual partners improved by 70% to 87%, and the combined application of sildenafil after surgery was more effective. Penile prostheses can be divided into two basic types: expandable and non-expandable. The expandable penile prosthesis device is favored by most patients because it is more compatible with physiological erection. However, prosthetic implants have two serious complications, namely infection and machine failure. Infection is the most significant and devastating complication and is commonly seen 6 months post-operatively, mostly due to epidermal gram-positive bacterial infections. In response to this complication, current expandable prostheses are being improved, with devices with antibiotic coats and devices with hydrophilic coats significantly reducing infection rates. Studies have demonstrated a statistically significant reduction in infection rates from 1.61% to 0.68% over 6 months with devices with an antibiotic coat. A similar study confirmed that hydrophilic devices used after pre-surgical immersion in antibiotic fluid for a one-year follow-up had an infection rate of 1.06%, compared to 2.07% for non-users. Expandable prosthesis machine failure problems seem to be less common than infection, and the type of design in recent years has greatly improved the reliability of the device, most machine failures occur after 4 years of prosthesis implantation, re-installation and removal of the prosthesis and other circumstances reduce the incidence of machine failure, it is estimated that the current application of the three-piece device is 90-95% effective over 5 years. 2, penile artery reconstruction surgery after pelvic fracture or perineal trauma ED often has arterial stenosis or insufficient blood supply, the need to increase penile blood inflow through arterial revascularization to restore normal erection Sarramon et al. used submental artery-dorsal penile artery anastomosis, or deep dorsal penile vein arterialization, postoperative 27% to 94% of patients can Drogo et al. reported [10] that 42 patients underwent submental artery-dorsal penile artery anastomosis and 8 patients underwent submental artery-dorsal penile vein anastomosis, with a postoperative satisfaction rate of 36% to 91%. . 3.Penile vein surgery For various reasons causing venous leakage while arterial blood flow is normal, surgical ligation, excision or embolization of the vein is required to restore normal erection by increasing the intracavernosal pressure of the penis. Hsien-sheng Wen et al. considered venous surgery combined with sildenafil as an encouraging treatment for patients with veno-vascular ED. They divided 128 patients into two groups; 65 patients underwent venous ligation and stripping followed by oral treatment with 12.5-100 mg sildenafil, with pre- and post-operative IIEF-5 scores of 9.2 ± 5.0 and 15.1 ± 5.0, and 20.1 ± 5.4 after oral sildenafil; the control group of 63 In the control group of 63 patients who received 100 mg of sildenafil orally alone, the scores were 9.4 ± 3.9 and 10.7 ± 3.5 before and after treatment, and the results were statistically significant. IV. Gene therapy This treatment method has received close attention as a representative of the new era of medical development. The penis, with its structural advantages such as protrusion in vitro, easy accessibility and the presence of potassium channels, is a natural and ideal organ for gene transfer therapy. Therefore, there have been numerous studies in this area, including the introduction of NOS genes into the smooth muscle of the penile corpus cavernosum to enhance erectile function, and sildenafil to enhance the efficacy of NOS genes in correcting erectile function; the transfer of superoxide dismutase (SOD) into the penile corpus cavernosum of aged rats to significantly reduce the formation of O2- and restore their erectile function; the transfer of vascular endothelial growth factor (VEGF) genes into the penis of adult rats using adenovirus However, these experiments are still at the stage of animal testing. The efficacy and safety of hMaxi-K gene transfer using an animal model for the treatment of ED in the elderly and diabetics containing a plasmid that does not cause allergic reactions was demonstrated several years ago. hMaxi-K gene transfer in nine patients by Melman et al. recently reported no associated negative events or changes in electrolytes, hormones, and other laboratory tests, thus confirming that ion channel hMaxi-K gene transfer is safe for ED patients. Gene transfer trials require 15 years of follow-up and are a slow process, but it is believed that gene therapy will eventually be used in the clinic. The choice of treatment is specific to the patient’s condition and expectations of treatment, and because of this individual variability, different treatments are needed in the clinic depending on the cause and characteristics of the condition. Various treatment methods have their corresponding efficiency and safety, and cannot be suitable for all patients, so the ideal ED treatment method is still subject to serious challenges. At present, many scholars believe that the treatment of ED will produce better results with combination therapy, but further research is needed to confirm the effectiveness and feasibility of combination therapy and to provide a reasonable treatment plan.