Chen, Po-Hsun, et al. “Effects of statins on all-cause mortality at different low-density-lipoprotein cholesterol levels in Asian patients with type 2 diabetes.” Current medical research and opinion 34.11 (2018): 1885-1892.

PDE5 Mechanism of action

Corbin, J. D. “Mechanisms of action of PDE5 inhibition in erectile dysfunction.” International journal of impotence research 16.1 (2004): S4-S7.

Kass, David A., et al. “Phosphodiesterase regulation of nitric oxide signaling.” Cardiovascular research 75.2 (2007): 303-314.

Burnett, Arthur L. “Phosphodiesterase 5 mechanisms and therapeutic applications.” The American journal of cardiology 96.12 (2005): 29-31.

https://www.liquisearch.com/sildenafil/mechanism_of_action

The mechanism of action of sildenafil involves the protection of cyclic guanosine monophosphate (cGMP) from degradation by cGMP-specific phosphodiesterase type 5 (PDE5) in the corpus cavernosum. Nitric oxide (NO) in the corpus cavernosum of the penis binds to guanylate cyclase receptors, which results in increased levels of cGMP, leading to smooth muscle relaxation (vasodilation) of the intimal cushions of the helicine arteries. This smooth muscle relaxation leads to vasodilation and increased inflow of blood into the spongy tissue of the penis, causing an erection. Robert F. Furchgott, Ferid Murad and Louis Ignarro won the Nobel Prize in Physiology or Medicine in 1998 for their independent study of the metabolic pathway of nitric oxide in smooth muscle vasodilation.

Sildenafil is a potent and selective inhibitor of cGMP-specific phosphodiesterase type 5 (PDE5), which is responsible for degradation of cGMP in the corpus cavernosum. The molecular structure of sildenafil is similar to that of cGMP and acts as a competitive binding agent of PDE5 in the corpus cavernosum, resulting in more cGMP and better erections.

Phosphodiesterase Inhibitors and Diabetes

Santi, Daniele, et al. “Therapy of endocrine disease: effects of chronic use of phosphodiesterase inhibitors on endothelial markers in type 2 diabetes mellitus: a meta-analysis.” European journal of endocrinology 172.3 (2015): R103-R114.

Anderson, Simon G., et al. “Phosphodiesterase type-5 inhibitor use in type 2 diabetes is associated with a reduction in all-cause mortality.” Heart 102.21 (2016): 1750-1756.

Cardiac risk factors and prevention

Phosphodiesterase type-5 inhibitor use in type 2 diabetes is associated with a reduction in all-cause mortality

Simon G Anderson1,2, David C Hutchings1, Mark Woodward2,3, Kazem Rahimi2, Martin K Rutter4,5, Mike Kirby6, Geoff Hackett7, Andrew W Trafford1, Adrian H Heald8,9

Abstract

Objective Experimental evidence has shown potential cardioprotective actions of phosphodiesterase type-5 inhibitors (PDE5is). We investigated whether PDE5i use in patients with type 2 diabetes, with high-attendant cardiovascular risk, was associated with altered mortality in a retrospective cohort study.

Research design and methods Between January 2007 and May 2015, 5956 men aged 40–89 years diagnosed with type 2 diabetes before 2007 were identified from anonymised electronic health records of 42 general practices in Cheshire, UK, and were followed for 7.5 years. HRs from multivariable survival (accelerated failure time, Weibull) models were used to describe the association between on-demand PDE5i use and all-cause mortality.

https://heart.bmj.com/content/102/21/1750.abstract
Anderson, Simon G., et al. “Phosphodiesterase type-5 inhibitor use in type 2 diabetes is associated with a reduction in all-cause mortality.” Heart 102.21 (2016): 1750-1756.

Of the total cohort, we identified men who had received a pre-
scription of a PDE5i (sildenafil, vardenafil or tadalafil) prior to
1 January 2007 and at least once, up to 30 June 2015.

A total of 5956 men with known type 2 diabetes aged 40–
89 years were identified at cohort entry date of 1 January 2007.
Of the total, 1359 (22.8%) received a PDE5i, prescribed a

All-cause mortality
Participants were followed up for a mean of 7.5 years (range
0.4–8.5 years). From the same background population, a
random (reference) sample of 32 330 men without diabetes or
PDE5i use, followed up for a mean 8.3 years, had mortality
rates of 4.8 (4.5 to 5.0) per 100 person-years. Fewer deaths (age
adjusted) occurred among PDE5i users with type 2 diabetes:
248 (19.1%) versus non-users (1170, (23.8%); 2=12.47,
p=0.0004).

Men on treatment with a PDE5i had a 31% lower risk of all-
cause mortality compared with non-users

Among those with a prior history of MI (n=1031), there were
fewer deaths in those previously treated with a PDE5i compared
with those who were never treated (25.7% (49/191) vs 40.1%
(337/840)).

Results Compared with non-users, men who are prescribed PDE5is (n=1359) experienced lower percentage of deaths during follow-up (19.1% vs 23.8%) and lower risk of all-cause mortality (unadjusted HR=0.69 (95% CI: 0.64 to 0.79); p<0.001)). The reduction in risk of mortality (HR=0.54 (0.36 to 0.80); p=0.002) remained after adjusting for age, estimated glomerular filtration rate, smoking status, prior cerebrovascular accident (CVA) hypertension, prior myocardial infarction (MI), systolic blood pressure, use of statin, metformin, aspirin and β-blocker medication. PDE5i users had lower rates of incident MI (incidence rate ratio (0.62 (0.49 to 0.80), p<0.0001) with lower mortality (25.7% vs 40.1% deaths; age-adjusted HR=0.60 (0.54 to 0.69); p=0.001) compared with non-users within this subgroup. Conclusion In a population of men with type 2 diabetes, use of PDE5is was associated with lower risk of overall mortality and mortality in those with a history of acute MI.

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! BEST !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Hackett, Geoffrey, et al. “Statin, testosterone and phosphodiesterase 5-inhibitor treatments and age related mortality in diabetes.” World journal of diabetes 8.3 (2017): 104. We show that statins, PDE5I and TRT reduce mortality in diabetes. PDE5I, alone and with the other treatments significantly alter age related mortality in diabetic men. METHODS We studied 857 diabetic men screened for the BLAST study, stratifying them (mean follow-up = 3.8 years) into: (1) Normal T levels/untreated (total T > 12 nmol/L and free T > 0.25 nmol/L), Low T/untreated and Low T/treated; (2) PDE5I/untreated and PDE5I/treated; and (3) statin/untreated and statin/treated groups. The relationship between age and mortality, alone and with T/TRT, statin and PDE5I treatment was studied using logistic regression. Mortality probability and 95%CI were calculated from the above models for each individual.

Four PDE5i are currently FDA approved for the
treatment of ED:
sildenafil (Viagra®),
tadalafil (Cialis®),
vardenafil (Levitra®, Staxyn®), and
avanafil (Stendra®).

Drug Time to Onset Duration of
Avanafil 15 minutes 6 hours
Vardenafil 20-30 minutes 8-12 hours
Sildenafil 30-60 minutes 2-4 hours
Tadalafil 60-120 minutes 36 hours
Activity Onset Delayed by High Fat Meal
Yes
Yes
Yes
No

Only tadalafil is indicated for daily dosing, all others are dosed as needed prior to sexual
activity. Pharmacodynamically, these medications differ in their time to onset and duration of activity5,6,7,8

PDE5 inhibitors for Diabetics with Peripheral Neuropathy

https://pubmed.ncbi.nlm.nih.gov/16939556/
Hackett G. PDE5 inhibitors in diabetic peripheral neuropathy. Int J Clin Pract. 2006 Sep;60(9):1123-6. doi: 10.1111/j.1742-1241.2006.01087.x. PMID: 16939556.

Abstract

Peripheral neuropathy is the most common complication of diabetes. This paper reviews the case histories of five patients with diabetic peripheral neuropathy or severe peripheral vascular disease who reported improvement in their symptoms when treated with regular or daily dosing with phosphodiesterase type 5 inhibitors (PDE5Is). These patients had been previously treated with PDE5Is for erectile dysfunction (ED) and not responded to on-demand therapy with a PDE5I at maximal recommended dose. This improvement is likely to be due to the known benefit of these drugs on endothelial dysfunction via an improvement of blood supply to the vasa nervorum. These cases suggest that further research is indicated to evaluate the potential use of PDE5Is in the treatment and prevention of diabetic peripheral neuropathy, particularly as these drugs are already licensed to treat ED, which occurs in around 50% of male diabetics.

How I reversed my Levaquin-induced neuropathy with PDE5 Inhibitors from neuropathy

How I reversed my Levaquin-induced neuropathy with PDE5 Inhibitors

In 2015, I developed a horrible, nearly 2 year-long status of being clinically disabled due to only 2x pills of Levaquin which started a chain reaction in my body. Since that time, I developed abnormal sweating in my feet/hands, episodic pain and more, which got worse after my doctor told me my fasting blood glucose was borderline pre-diabetic; Levaquin, like other FQs, appears to cause significant dysglycemia (Friedrich and Dougherty 2004, Singh and Jacob 2008, Kelesidis and Canseco 2009) Dysglycemia is a broad term that refers to an abnormality in blood sugar stability, which is what I had, post-Levaquin. According to Telfer (2014), Fluoroquinolones seem to induce intracellular magnesium deficiency, as the 3-carboxyquinolone substructure of FQs is metal-cleating, and 6-fluoro substituent on the pharmacophore gives rise to sufficient lipophilicity that the drugs can dissolve in and penetrate cell membranes. It has also been suggested that intracellular fluoroquinolones can exist as a magnesium complex! Cellular Diffusion and/or Active Transport of such a complex would deplete Magnesium from the cells. (Lecomte et al., 1994; Bensikaddour, 2008) The effects of fluoroquinolones on intracellular magnesium levels might be considered to be almost cumulative, and slow to reverse overall. (Jahnen-Dechent and M. Ketteler, 2012) . Magnesium affects blood sugar stability, so there was the cause.

Neurological workup was initially unremarkable, but followups showed reduced Nerve Velocity in my feet, reduced nerve density and more. The pain started getting worse, with being unable to tolerate clothing or heat. The doctor wanted to prescribe me the usual cocktails of medications to ‘hide’ the pain. No thanks – I’ll use my scientific background to see about alternative treatments.

Hello ED medications! (PDE5s)

PDE5 Inhibitors, like Viagra, improve neuropathy in human studies, as well as animal studies. (Wang et al., 2017; 2016; 2015; 2011; Mostafa, 2008; Peixoto et al., 2015; Vlachopoulos et al., 2009; Hackett, 2006; Mehmet Fatih Korkmaz et al., 2016; etc) This behavior was described as early as 2002 (Sairam and McNicholas, 2002).

PN symptoms in Fluroquoinoline Patients are more or less the same in Diabetic Patients, as PN initially manifests itself as mitochondrial dysfunction.

PDE5I’s are showing other benefits, such as increased antioxidant status in humans, cardioprotection, and more.

According to Hackett (2006), 5 patients who were prescribed different PDE5Is showed dramatic results within 90 days, with some of the patients showing a nearly complete reversal of neuropathic pain. However, their T2D was quite advanced, so keep that in mind.

The mechanisms behind PDE5I treatments are well documented; Tadalafil treatment improves motor and sensory conduction velocities in the sciatic nerve and peripheral thermal sensitivity, increased myelin thickness, enhances Nerve Growth Factor, regional blood flow in Sciatic Nerve Tissue, and more. (Wang, et al., 2016; 2017). Daily dosages of Tadalafil for a period of 90 days will likely reverse early-to-moderate stages of Neuropathy.

Going over the Pharmacodynamics of the PDE5is, Sildenafil (Viagra) has a biological half-life of 4 hours, which is likely /too/ short for effective treatment. Tadalafil has a biological half-life of 17 hours, with a great safety profile. However, Tadalafil, unlike Sildenafil, has no absorption issues when combined with food, etc. (Nichols, Muirhead and Harness, 2002), so Tadalafil is likely a better medication for treatment.

I started taking Tadalafil every 48 hours for about a month. Within the first week, my feet were feeling much better, 2 weeks later, my feet were able to sweat like normal. The pain was reduced by at least 60% on week 2. However, I had to start taking antiacids because the Tadalafil was giving me horrible acid reflux. I continued to take it for about 2 months.

A few months later, I visited my neurologist and demanded another full panel. Nerve Conduction Velocity had improved so much that is was within the ‘normal’ range for my peripheral nerves. Punch biopsy showed increased density as well. I was no longer in any pain, really, except for the occasional pins-and-needles feeling when my feet are just too cold for being outside in the winter.

If you are a male and have neuropathy from Diabetes or something else, you could ask your doctor to write you a prescription for a PDE5 and see if it helps you. I don’t know if women could take PDE5s.

Citations;

– Sairam K, McNicholas T. Sildenafil in diabetic peripheral neuropathy. Br J Diabetes Vasc Dis 2002
– Korkmaz MF, Parlakpinar H, Ceylan MF, et al. The Effect of Sildenafil on Recuperation from Sciatic Nerve Injury in Rats. Balkan Med J. 2016;33(2):204–211. doi:10.5152/balkanmedj.2016.14701
– Wang L, Chopp M, Szalad A, Lu X, Jia L, Lu M, Zhang RL, Zhang ZG. Tadalafil Promotes the Recovery of Peripheral Neuropathy in Type II Diabetic Mice. PLoS One. 2016
– Wang L, Chopp M, Szalad A, Liu Z, Bolz M, Alvarez FM, Lu M, Zhang L, Cui Y, Zhang RL, Zhang ZG. Phosphodiesterase-5 is a therapeutic target for peripheral neuropathy in diabetic mice. Neuroscience. 2011
– L. Wang, M. Chopp, A. Szalad, Z. Liu, M. Bolz, F.M. Ãlvarez, M. Lu, L. Zhang, Y. Cui, R.L. Zhang, and Z.G. Zhang, Phosphodiesterase-5 is a therapeutic target for peripheral neuropathy in diabetic mice, Neuroscience, 193, (399), (2011).
– Lei Wang, Michael Chopp, and ZhengGang Zhang, PDE5 inhibitors promote recovery of peripheral neuropathy in diabetic mice, Neural Regeneration Research, 12, 2, (218), (2017).
– Christina Alves Peixoto, Ana Karolina Santana Nunes, and Ana Garcia-Osta, Phosphodiesterase-5 Inhibitors: Action on the Signaling Pathways of Neuroinflammation, Neurodegeneration, and Cognition, Mediators of Inflammation, 10.1155/2015/940207, 2015, (1-17), (2015).
– Lei Wang, Michael Chopp, Alexandra Szalad, LongFei Jia, XueRong Lu, Mei Lu, Li Zhang, Yi Zhang, RuiLan Zhang, Zheng Gang Zhang and Julie A. Chowen, Sildenafil Ameliorates Long Term Peripheral Neuropathy in Type II Diabetic Mice, PLOS ONE, 10, 2, (e0118134), (2015).
– Taymour Mostafa, Oral Phosphodiesterase Type 5 Inhibitors: Nonerectogenic Beneficial Uses, The Journal of Sexual Medicine, 5, 11, (2502-2518), (2008).
– C. Vlachopoulos, D. Terentes-Printzios, N. Ioakeimidis, K. Rokkas, and C. Stefanadis, “ PDE5 Inhibitors in Non-Urological Conditions”, Current Pharmaceutical Design (2009) 15: 3521. https://doi.org/10.2174/138161209789206980
– Duranti G, Ceci R, Sgrò P, Sabatini S, Di Luigi L. Influence of the PDE5 inhibitor tadalafil on redox status and antioxidant defense system in C2C12 skeletal muscle cells. Cell Stress Chaperones. 2017;22(3):389–396. doi:10.1007/s12192-017-0778-9
– The phosphodiesterase 5 inhibitor sildenafil stimulates angiogenesis through a protein kinase G/MAPK pathway. Pyriochou A, Zhou Z, Koika V, Petrou C, Cordopatis P, Sessa WC, Papapetropoulos A. J Cell Physiol. 2007 Apr;211(1):197-204.

– Pauls MM, Moynihan B, Barrick TR, Kruuse C, Madigan JB, Hainsworth AH, Isaacs JD. The effect of phosphodiesterase-5 inhibitors on cerebral blood flow in humans: A systematic review. J Cereb Blood Flow Metab. 2018 Feb;38(2):189-203.

daily tadalafil 5 mg, and L-arginine 2500.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8756145/

Gallo, Luigi, Stefano Pecoraro, and Pasquale Sarnacchiaro. “Adjuvant daily therapy with L-arginine 2,500 mg and tadalafil 5 mg increases efficacy and duration of benefits of low-intensity extracorporeal shock wave therapy for erectile dysfunction: A prospective, randomized, single-blinded study with 1-year follow-up.” Investigative and Clinical Urology 63.1 (2022): 83.

Purpose: To investigate a therapeutic protocol for erectile dysfunction (ED) based on the combination of low-intensity extracorporeal
shock wave therapy (Li-ESWT), tadalafil, and L-arginine.

Materials and Methods: Recruited patients completed the International Index of Erectile Function erectile function domain (IIEFEF)
and the Erection Hardness Score (EHS) questionnaires at baseline and were randomly assigned in two groups: A (treatment
group) and B (control group). Men in both groups received six weekly applications of Li-ESWT. Group A was prescribed adjuvant
oral therapy with tadalafil 5 mg and L-arginine 2,500 mg. Follow-up visits were scheduled 1, 6, and 12 months after the last Li-ESWT
application. At each follow-up visit, the IIEF-EF and EHS questionnaires were administered again. The main outcome measures
were the changes from baseline to every follow-up visit in IIEF-EF and EHS scores.
Results: The mean IIEF-EF score in group A was 16.0±4.0, 24.8±3.4, 23.3±4.6, and 21.6±5.5 at baseline, 1, 6, and 12 months of
follow-up, respectively, whereas in group B the mean IIEF-EF score was 16.5±4.1, 22.7±4.2, 21.5±4.5, and 19.5±4.9, respectively.
We reported an increase in the mean EHS score in group A from 2.07±0.72 at baseline to 3.39±0.59, 3.17±0.67, and 2.98±0.72 at 1,
6, and 12 months, respectively, and in group B from 2.12±0.80 at baseline to 3.07±0.78 and 2.95±0.76 at 1 and 6 months, respectively.
Conclusions: Adjuvant daily therapy with L-arginine 2,500 mg and tadalafil 5 mg was safe and effective in increasing the efficacy
and the duration of benefits of Li-ESWT.

https://onlinelibrary.wiley.com/doi/full/10.1111/andr.12671

El‐Wakeel, L. M., et al. “Efficacy and tolerability of sildenafil/l‐arginine combination relative to sildenafil alone in patients with organic erectile dysfunction.” Andrology 8.1 (2020): 143-147.

Randomized controlled study with two parallel groups of erectile dysfunction patients; One group received sildenafil 50 mg every other day, while the other group received a combination of sildenafil (every other day)/l-arginine on a daily base. Efficacy was assessed using International Index of Erectile Function-5 score at the baseline and after 8 weeks. Side effects were evaluated across the two groups.
Results

The mean age was 56.3 ± 5 and 56.2 ± 4.4 years in sildenafil and combination groups, respectively. International Index of Erectile Function-5 score was comparable between the two groups at the baseline (p value 0.44). International Index of Erectile Function-5 score was improved from 15.3 ± 2.5 at baseline to 19.2 ± 2.3 after treatment, and this was statistically significant with p value <0.0001. The score was slightly better in combination group in which the average International Index of Erectile Function-5 score was (19.8 ± 2.2) vs. (18.5 ± 2.3) in sildenafil group with p value 0.05. Side effects were more or less the same between the two groups except for gastritis which was more common on combination group.
Conclusion

Adding l-arginine to sildenafil demonstrated more efficacy than sildenafil alone for treatment of erectile dysfunction patients.

Mirone, Vincenzo, et al. “A new original nutraceutical formulation ameliorates the effect of Tadalafil on clinical score and cGMP accumulation.” Archivio Italiano di Urologia e Andrologia 93.2 (2021): 221-226.

https://jamanetwork.com/journals/jamaophthalmology/article-abstract/2790661
Risk of Ocular Adverse Events Associated With Use of Phosphodiesterase 5 Inhibitors in Men in the US
Mahyar Etminan, PharmD, MSc1,2,5; Mohit Sodhi, MSc1,3; Frederick S. Mikelberg, MD1; et al

Chronic Pelvic Pain Syndrome

https://tau.amegroups.com/article/view/38522/30198
Pineault, Kevin, et al. “Phosphodiesterase type 5 inhibitor therapy provides sustained relief of symptoms among patients with chronic pelvic pain syndrome.” Translational Andrology and Urology 9.2 (2020): 391.

Contributions: (I) Conception and design: K Pineault, AS Herati; (II) Administrative support: AS Herati; (III) Provision of study materials or patients: K Pineault, AS Herati; (IV) Collection and assembly of data: All authors; (V) Data analysis and interpretation: K Pineault, S Ray; (VI) Manuscript writing: all authors; (VII) Final approval of manuscript: All authors.
Correspondence to: Amin S. Herati, MD. Department of Urology, The James Buchanan Brady Urological Institute, Johns Hopkins University School of Medicine, Park Building 217, 600 North Wolfe St., Baltimore, MD 21287, USA. Email: aherati1@jhmi.edu.

A total of 25 patients (mean age 44.4±12.9 years) met study criteria. The mean duration of PDE5i therapy was 1.3±1.6 years. Continued use of daily PDE5is was associated with significant decreases in total CPSI, pain, urinary symptom and quality of life scores [total CPSI: −12.8, standard deviation (SD) 9.5; pain: −6.1, SD 4.1; urinary symptoms: −2.4, SD 2.1; quality of life: −4.5, SD 3.9; P<0.001].

Conclusions: This prospective data suggests that PDE5i therapy is associated with durable decreases in CP/CPPS symptoms past 3 months.

Benelli, Andrea, et al. “Once-daily 5 mg tadalafil oral treatment for patients with chronic prostatitis/chronic pelvic pain syndrome.” Therapeutic Advances in Urology 10.12 (2018): 377-381.

Demirtaş, Abdullah, et al. “Is Tadalafil an Effective Treatment Option for Interstitial Cystitis/Painful Bladder Syndrome? A Report of a Challenging Case.” Cureus 13.7 (2021).

BPH

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4054509/
Hatzimouratidis, Konstantinos. “A review of the use of tadalafil in the treatment of benign prostatic hyperplasia in men with and without erectile dysfunction.” Therapeutic Advances in Urology 6.4 (2014): 135-147. Tadalafil 5 mg once daily has been approved for the treatment of men with LUTS with or without comorbid ED.

Singh, Sanket Narayan, et al. “Comparing the effect of Alpha blocker (Silodosin) and Phosphodiesterase type 5 inhibitor (Tadalafil) in benign prostate hyperplasia patients with lower urinary tract symptoms: a single centre study.” International Surgery Journal 5.5 (2018): 1866-1872.

Casabé, Adolfo, et al. “Efficacy and safety of the coadministration of tadalafil once daily with finasteride for 6 months in men with lower urinary tract symptoms and prostatic enlargement secondary to benign prostatic hyperplasia.” The Journal of urology 191.3 (2014): 727-733.

https://link.springer.com/article/10.1007/s10557-019-06851-7
Cai, Zhonglin, Jianzhong Zhang, and Hongjun Li. “Two birds with one stone: regular use of PDE5 inhibitors for treating male patients with erectile dysfunction and cardiovascular diseases.” Cardiovascular Drugs and Therapy 33.1 (2019): 119-128.

PDE5 for Neurologic and Cognitive Function

Peixoto, Christina Alves, Ana Karolina Santana Nunes, and Ana Garcia-Osta. “Phosphodiesterase-5 inhibitors: action on the signaling pathways of neuroinflammation, neurodegeneration, and cognition.” Mediators of Inflammation 2015 (2015).

Peixoto, Christina A., Ana KS Nunes, and Catarina Rapôso. “The role of NO/cGMP signaling on neuroinflammation: a new therapeutic opportunity.” Mechanisms of neuroinflammation (2017): 167-208.

Nabavi, Seyed Mohammad, et al. “Phosphodiesterase inhibitors say NO to Alzheimer’s disease.” Food and Chemical Toxicology 134 (2019): 110822.

Ben Aissa, Manel, et al. “Targeting NO/cGMP signaling in the CNS for neurodegeneration and Alzheimer’s disease.” Current medicinal chemistry 23.24 (2016): 2770-2788.

de Santana Nunes, Ana Karolina, et al. “Sildenafil (Viagra®) prevents and restores LPS-induced inflammation in astrocytes.” Neuroscience Letters 630 (2016): 59-65.

França, Maria Eduarda Rocha, et al. “Tadalafil restores long-term memory and synaptic plasticity in mice with hepatic encephalopathy.” Toxicology and Applied Pharmacology 379 (2019): 114673.

Wang, Lei, Michael Chopp, and Zheng Gang Zhang. “PDE5 inhibitors promote recovery of peripheral neuropathy in diabetic mice.” Neural regeneration research 12.2 (2017): 218.

da Rocha Araújo, Shyrlene Meiry, et al. “Effect of sildenafil on neuroinflammation and synaptic plasticity pathways in experimental autoimmune encephalomyelitis.” International Immunopharmacology 85 (2020): 106581.

Duarte-Silva, Eduardo, et al. “Phosphodiesterase-5 inhibitors: Shedding new light on the darkness of depression?.” Journal of Affective Disorders 264 (2020): 138-149.

El-Bakly, Wesam, et al. “The efficacy and underlying mechanism of phosphodiesterase-5 inhibitors in preventing cognitive impairment and Alzheimer pathology: A systematic review of animal studies.” Behavioural Brain Research 372 (2019): 112004.