Stesura Seveso Archivio Italiano di Urologia e Andrologia 2024; 96(1):12248 1 ORIGINAL PAPER the urethral strictures with balloon dilation (4). The suc- cessful effect of the drug requires its distribution to the muscle layer of the urethra where the smooth muscle cells are present (5). These cells are responsible for restenosis through their proliferation and production of inappropri- ate collagen (6). Paclitaxel has been proven to inhibit the proliferation of these cells and reduce the production of collagen (7, 8). Thus, the use of paclitaxel-coated bal- loons for the prevention of restenosis after balloon dila- tion seems to be a promising approach. The distribution of paclitaxel in the normal rabbit urethra has already been evaluated (9). The aim of this experimental study is to provide evidence about the benefits of the application of DCBs in urethral strictures. The current protocol aims to provide evidence on the distribution of paclitaxel (PTX) in the wall of the strictured urethra of rabbits. The drug should be distributed to the muscle layer of the urethra in order to achieve maximal efficiency. Moreover, data regarding the efficacy of this approach on the recurrence of the urethral strictures treated by the paclitaxel-coated balloons will be presented. Materials and Methods Ethical standards The current experimental trial was pre-approved by the Veterinary Administration of the Prefecture of Western Greece and the animals were treated according to the cur- rent veterinary protocols. Experimental models Eighteen domestic male rabbits weighing between 3-4 kg were included in the conduction of the current experi- mental study. Sedation The rabbits were sedated by intramuscular injection with a combination of ketamine and xylazine. Intervention The experimental models were placed in the supine posi- Purpose: The aim of this study is the evalua- tion of the distribution of Paclitaxel (PTX) released by a coated balloon in the layers of rabbit’s urethra. Methods: 18 rabbits were included. A Laser Device was used for the stricture formation. After two weeks, dilation of the stric- tured urethra was performed by using Advance 35LP PTA balloons and Advance 18 PTX PTA balloons. The experimental models were divided into 3 groups. The group Α included two rabbits without any intervention except for the stenosis proce- dure. Group B compromised six rabbits that underwent dilation with Advance 35LP PTA balloons. Group C consisted of 10 rabbits to which dilation with both Advance 35LP PTA balloons and Advance 18 PTX PTA balloons was applied. Histological evaluation and Immunohistochemistry were performed on all specimens. Results: Inflammation, fibrosis and ruptures were detected in the specimens of the study. In specimens of Group C the decrease of inflammation and fibrosis rate was greater. Anti-PTX antibody was detected in the epithelium, lamina propria and smooth mus- cle layer of all specimens of urethras that have been harvested immediately and 1 day after the dilation with Advance 18 PTX PTA balloon and it was not observed in any layer of the ure- thral wall of the rest of the examined specimens of Group C. Conclusions: PTX’s enrichment was detected in the smooth muscle layer of all specimens that have been harvested immedi- ately and 24h after the dilation with Advance 18 PTX PTA bal- loons. PTX may play an inhibitive role in the recurrence of the stenosis. KEY WORDS: Urethra; Stricture; Balloon; Dilation; Paclitaxel. Submitted 31 December 2023; Accepted 17 January 2024 INTRODUCTION Urethral strictures constitute a significant urological dis- ease that presents a high incidence in the male population (1). The available minimally invasive approaches are associated with high recurrence rates (2). Drug Coated Balloons (DCBs) that release cytostatic substances have been used for the prevention of vascular stenosis (3). In the same concept, these balloons can be used for the reduction of the recurrence rates after the management of Minimal invasive treatment of urethral strictures: An experimental study of the effect of Paclitaxel coated balloons in the wall of strictured rabbit’s urethra Konstantinos Pagonis 1, Angelis Peteinaris 1, Constantinos Adamou 1, Vasileios Tatanis 1, Athanasios Vagionis 1, Anastasios Natsos 1, Mohammed Obaidat 1, Solon Faitatziadis 1, Evangelos Liatsikos 1, 2, Panagiotis Kallidonis 1 1 Department of Urology, University Hospital of Rion, Patras, Greece; 2 Medical University of Vienna, Vienna, Austria. DOI: 10.4081/aiua.2024.12248 Summary Archivio Italiano di Urologia e Andrologia 2024; 96(1):12248 K. Pagonis, A. Peteinaris, C. Adamou, et al. 2 tion. A urethroscopy was conducted on each rabbit by using a 7FR pediatric nephroscope (Storz 27095AA Pediatric Nephroscope Set, Karl Storz SE & Co. KG, Tuttlingen, Germany) . Stricture formation took place by using the Thulium fiber laser device (Quanta Fiber Dust, Samarate, Italy) with a 200-μm fiber and power settings 8W (0.5J x 16Hz). Strictures were formed in the penile urethra approximately 1-2 cm before the sphincter (Figure 1). After 2 weeks, an urethrography and an ure- throscopy of each model were held. The presence of a urethral stricture of approximately 1 cm in length in all experimental models was confirmed by these procedures. Dilation of the stricture with Advance 35LP- high pres- sure balloon (HPB) (Cook Medical, Cook Ireland Ltd., Limerick, Ireland - 16, diameter 6 mm/ length 40 mm) and Advance 18PTX- DCB (Cook Medical, Cook Ireland Ltd., Limerick, Ireland – 16, diameter 6 mm/ length 40 mm) depending on the study group was conducted in the same session (Figure 2). A 0.035’’ inch hydrophilic guidewire was inserted into each urethral lumen under fluoroscopic guidance. A stiff guidewire exchanged the hydrophilic wire over a 7 Fr ureteral catheter (Cook Medical, Cook Ireland Ltd., Limerick, Ireland). The bal- loon dilator was placed over the stiff guidewire and inflat- ed to its maximum pressure of 8 atm for at least 5 min- utes and then was emptied and removed. Follow-up to 6 weeks with urethrography every 2 weeks depending on the study group took place. Study groups The experimental models were divided into 3 main groups (groups A, B, and C). The rabbits were sacrificed on spe- cific time periods and the whole length their urethra was obtained. Group A: The control group included 2 experi- mental models where stricture formation was performed without any other intervention. These specimens were obtained two weeks after the stricture formation. Group B: 6 rabbits were included in this group. Two weeks after the stricture formation, dilation with HPB took place. The subgroups were divided based on the postoperative duration until the harvesting of the ure- thras to provide information on the stricture condition after conventional balloon dilation. All subgroups includ- ed 2 rabbit’s urethras and were defined as: Group B.1: Harvested urethras 2 weeks after the dilation procedure. Group B.2: Harvested urethras 4 weeks after the dilation procedure. Group B.3: Harvested urethras 6 weeks after the dilation procedure. Group C: 10 experimental models were included in this study group. Two weeks after the stenosis formation, dilation with HPB, at first, and then with DCB took place at the same time. The subgroups were divided in the same way as in Group B. 2 rabbit’s urethras were included in each subgroup. The subgroups of group C were defined as: Group C.1: Harvested urethras immediately after the dila- tion procedure with both HPB and DCB. Group C.2: Harvested urethras 1 day after the dilation procedure with both HPB and DCB. Group C.3: Harvested urethras 2 weeks after the dilation procedure with both HPB and DCB. Group C.4: Harvested urethras 4 weeks after the dilation procedure with both HPB and DCB. Group C.5: Harvested urethras 6 weeks after the dilation procedure with both HPB and DCB. Figure 1. Endoscopic images before and after the stricture formation a. The laser fiber inside the urethral lumen during urethoscopy. b. The initiation of stricture formation. c. Urethral stricture 2 weeks after the initial intervention. Figure 2. Fluoroscopic images a. Antegrade urothrography. Recognition of the stricture (blue arrow). b. Dilation with Advance 18 PTX PTA balloon on the previously depicted stricture (orange arrow). a b a b c Archivio Italiano di Urologia e Andrologia 2024; 96(1):12248 3 Paclitaxel coated balloon for urethral stricture Pathology process The specimens of urethras were embedded in formalin and standard fixing process with paraffin was performed. 4μm- thick sections were enriched with hematoxylin/eosin and were placed on gelatin-eluting glass slides. Histological evaluation of the specimens All glass slides were tested by the same expert uropathol- ogist. This procedure is conducted by using a standard light microscope with an attached camera (Nikon ECLIPSE 50i and Nikon HD color camera head DS-Fi2, Nikon GmbH, Dusseldorf, Germany). Slides were received from each urethral specimen for the conduction of histol- ogy and immunohistochemistry. Morphological alterations (stricture, connective tissue for- mation) and inflammation were microscopically evaluat- ed. The inflammation rate of the urethral layers was esti- mated according to Nakada classification (10). Normal appearance of the urethra after microscopic examination was graded as 0 and severe inflammation was graded as 3. Immunohistochemistry (IHC) IHC was performed by using the monoclonal anti-body for IHC (Anti-Taxol antibody from Abcam). This process aimed into elucidating the enrichment of PTX in different layers of urethral wall. The PTX’s presence and the loca- tion of the agent in the examined slides was evaluated with IHC (Figure 3). RESULTS Histology Ruptures across the urethral wall and inflammation were observed in all specimens. In Group A the inflammation grade was 3 (according to Nakada classification), fibrosis was observed in all layers (squamous epithelium, submu- cosa, smooth muscle layer) of the urethra. In Groups B.1 and B.2 the inflammation grade was 2 and fibrosis was observed in all layers of the urethral tissue. In Group B.3 fibrosis in all layers of the urethral wall and inflammation (Grade 1) were observed. As for the Group C.1 and C.2, the inflammation Grade was 3 in both groups and fibrosis was observed in the epithelium tissue, submucosa and smooth muscle layer. Blood clots were found in both groups. In Group C.3 and C.4 the inflammation grade of the urethral wall was 2 and 1, respectively. Fibrosis was observed only in the squamous epithelium and submucos- al layer in both groups. In Group C.5 the inflammation grade was 1 and fibrosis was observed only in the epitheli- um tissue of the urethral wall. These results are presented in Table 1. Figure 3. Histolpathological Images from the urethral wall of the experimental models. a. Specimen from Group C.4 b. Specimen from Group C.1 Table 1. Histological findings of the harvested urethral specimens regarding the Inflammation Grade, Fibrotic Formation, and the integrity of the urethral lumen. Experimental Study Group Inflammation Grade Fibrosis Model (Nakada Classification) 1 A (stricture formation-no intervention) 3 • Squamous epithelium • Submucosa • Smooth Muscle Layer 2 A (stricture formation-no intervention) 3 • Squamous epithelium • Submucosa • Smooth Muscle Layer 3 B.1 (stricture formation-dilation 35LP PTA balloon-2 weeks) 2 • Squamous epithelium • Submucosa • Smooth Muscle Layer 4 B.1 (stricture formation-dilation 35LP PTA balloon-2 weeks) 2 • Squamous epithelium • Submucosa • Smooth Muscle Layer a b Archivio Italiano di Urologia e Andrologia 2024; 96(1):12248 K. Pagonis, A. Peteinaris, C. Adamou, et al. 4 IHC The specimens of Group C were examined for the pres- ence of the antibody of PTX. In all specimens examined of Group C.1 and C.2, the anti-PTX antibody was found in the squamous epithelium, submucosa and smooth muscle layer of rabbit’s urethra. In one specimen of group C.1, the anti-PTX antibody was observed, also, in the corpus cavernosum and the connective tissue of the rabbit’s penis. In the rest examined specimens of Group C the antibody wasn’t detected in any layer of the ure- thral wall. The results of the IHC are summarized in Table 2. DISCUSSION DCBs contribute to the treat- ment of atherosclerosis, in- stent recurrence of stenosis and the reduction of the risk of thrombosis without the placement of a permanent for- eign object (11-14). DCB is a standard angioplasty balloon coated with a drug, which is embedded in the matrix coat- ing by using a hydrophilic spacer in order to allow the drug to be released after the expansion of the balloon into the vessel lumen. Then, the drug is absorbed in the layers Table 2. Paclitaxel (PTX) distribution in the layers of the examined specimens of the urethral wall based on the Immunohistochemical report. Experimental Study Group Squamous Submucosal Smooth Muscle Model Epithelium Tissue Layer 9 C.1 (stricture formation-dilation 35LP PTA balloon+18 PTX PTA balloon-immediately) + + + 10 C.1 (stricture formation-dilation 35LP PTA balloon+18 PTX PTA balloon-immediately) + + + 11 C.2 (stricture formation-dilation 35LP PTA balloon+18 PTX PTA balloon -24h) + + + 12 C.2 (stricture formation-dilation 35LP PTA balloon+18 PTX PTA balloon -24h) + + + 13 C.3 (stricture formation-dilation 35LP PTA balloon+18 PTX PTA balloon-2 weeks) - - - 14 C.3 (stricture formation-dilation 35LP PTA balloon+18 PTX PTA balloon-2 weeks) - - - 15 C.4 (stricture formation-dilation 35LP PTA balloon+18 PTX PTA balloon-4 weeks) - - - 16 C.4 (stricture formation-dilation 35LP PTA balloon+18 PTX PTA balloon-4 weeks) - - - 17 C.5 (stricture formation-dilation 35LP PTA balloon+18 PTX PTA balloon-6 weeks) - - - 18 C.5 (stricture formation-dilation 35LP PTA balloon+18 PTX PTA balloon-6 weeks) - - - 5 B.2 (stricture formation-dilation 35LP PTA balloon-4 weeks) 2 • Squamous epithelium • Submucosa • Smooth Muscle Layer 6 B.2 (stricture formation-dilation 35LP PTA balloon-4 weeks) 2 • Squamous epithelium • Submucosa • Smooth Muscle Layer 7 B.3 (stricture formation-dilation 35LP PTA balloon-6 weeks) 1 • Squamous epithelium • Submucosa • Smooth Muscle Layer 8 B.3 (stricture formation-dilation 35LP PTA balloon-6 weeks) 1 • Squamous epithelium • Submucosa • Smooth Muscle Layer 9 C.1 (stricture formation-dilation 35LP PTA balloon+18 PTX PTA balloon-immediately) 3 • Squamous epithelium • Submucosa • Smooth Muscle Layer 10 C.1 (stricture formation-dilation 35LP PTA balloon+18 PTX PTA balloon-immediately) 3 • Squamous epithelium • Submucosa • Smooth Muscle Layer 11 C.2 (stricture formation-dilation 35LP PTA balloon+18 PTX PTA balloon -24h) 3 • Squamous epithelium • Submucosa • Smooth Muscle Layer 12 C.2 (stricture formation-dilation 35LP PTA balloon+18 PTX PTA balloon-24h) 3 • Squamous epithelium • Submucosa • Smooth Muscle Layer 13 C.3 (stricture formation-dilation 35LP PTA balloon+18 PTX PTA balloon-2 weeks) 2 • Squamous epithelium • Submucosa 14 C.3 (stricture formation-dilation 35LP PTA balloon+18 PTX PTA balloon-2 weeks) 2 • Squamous epithelium • Submucosa 15 C.4 (stricture formation-dilation 35LP PTA balloon+18 PTX PTA balloon-4 weeks) 1 • Squamous epithelium • Submucosa 16 C.4 (stricture formation-dilation 35LP PTA balloon+18 PTX PTA balloon-4 weeks) 1 • Squamous epithelium • Submucosa 17 C.5 (stricture formation-dilation 35LP PTA balloon+18 PTX PTA balloon-6 weeks) 1 • Squamous epithelium 18 C.5 (stricture formation-dilation 35LP PTA balloon+18 PTX PTA balloon-6 weeks) 1 • Squamous epithelium Archivio Italiano di Urologia e Andrologia 2024; 96(1):12248 5 Paclitaxel coated balloon for urethral stricture of the vessel wall and reduces the tissue formation which is the normal effect in cases of either balloon expansion or stent placement in the lumen of a vessel (15). The effect of DCBs is attributed to the cytostatic drugs which are coated onto the balloons (16). The currently drug of choice is PTX. PTX constitutes the most tested anti-pro- liferative drug for the urinary tract (17). The aim of our study is the distribution of PTX in the different layers of the urethral strictured wall. Barbalias et al. evaluated the distribution of PTX in the normal rabbit urethral wall (9). The researchers investigated the distribution of PTX in the layers of normal rabbit’s urethra after the inflation of a PTX-coated balloon. They proved that PTX was detect- ed to the epithelium, submucosal, and muscle layers of the normal rabbit’s urethra immediately after the dilata- tion procedure by using DCB. Also, PTX was found 24 and 48 hours after the dilatation process. Nonetheless, there is no evidence in this study if the substance is ade- quately distributed in the case of strictured urethra or the effectiveness of the approach. Another difference between the two studies was the timeline. In our study the exper- iment was conducted in 8 weeks and the follow up of the experimental models lasted up to 6 weeks. However, both studies proved that the smooth muscle layer was enriched by PTX in both normal and strictured urethras, even 6 weeks after the dilatation with DCBs. Fu et al. investigated the impact of docetaxel (PTX’s synthetic ana- logue) in management of urethral strictures (18). They randomly separated forty rabbits in 2 equal groups of 16 rabbits which received high and low dose of docetaxel respectively and a control group of 8 rabbits. Retrograde urethral irrigation was used for the administration of doc- etaxel, once per day for 28 days. Normal saline was administrated in the control group. The urethral diame- ters and the histological findings were evaluated. The diameter of the urethral lumen was significantly lower and the fibrosis and collagen concentration rate was greater in the control group compared to the other groups. These results are similar to the results of our study. Nevertheless, the researchers didn’t use any anti- body for testing the exact distribution of docetaxel in the different layers of rabbits’ urethras. Wikan et al. tested the role of docetaxel and captopril in RNA expression of TGF-β1, MMP-1, CTGF, PAI-1. These genes play an important role in the formation of fibrotic tissue. They tested four groups of rabbit’s urethra: a control group, a docetaxel group, a combined docetaxel/captopril group and a captopril group. They proved that, only, single doc- etaxel could decrease the expression of the 3 out of 4 pre- referred genes. Consequently, this PTX’s synthetic ana- logue could, also, contribute to the inhibition of fibrotic formation. Ji Hoon et al. evaluated the effect of PTX-coat- ed stents in dog’s canine urethra (19). They placed two stents (one PTX-coated stent and one polyurethane-coat- ed stent) in each urethral model, one in the proximal and one in the distal urethra. They separated the dogs in 2 equal groups of 10 individuals. First group’s models were sacrificed 4 weeks after the stent’s placement and second group’s models were sacrificed 8 weeks after the stent’s placement. In the first group, they placed the drug-coat- ed stent and the polyurethane-coated stent in the proxi- mal urethra and the distal urethra respectively in 5 dogs and, also, placed the same stents reversely in the remain- ing five dogs of the group. Retrograde urethrography was performed in each model just before the sacrifice of the models and proved that tissue hyperplasia was signifi- cantly less in PTX-coated stenting part of the urethra in both groups. The histological evaluation of their experi- mental study showed that the granulation formation, the papillary projection and the submucosal inflammatory were significantly less in PTX-stenting specimens in both the 4-week and the 8-week group. Even if they tested dif- ferent parameters in different experimental models, their outcomes strengthen theoretically the results of our study and provide evidence about the efficacy of PTX in the urethral tissue. Other experimental studies were, also, conducted in the past for the efficacy of PTX in other parts of the urinary tract. Liourdi et al. conducted an experimental study in porcine ureteral wall by using DCBs (20). The aim of this study was the elucidation of the possibility of the clinical use of DCBs in ureteral strictures. As for the results, we concluded that PTX was distributed in the urothelium, submucosal, and smooth muscle layers of porcine ureter. Also, the inflammation rate was lower in the PTX groups of the study. This result comes to agreement with the results of our study and proves the efficacy of PTX. Nevertheless, it is worth mentioning that the experimen- tal models and the anatomical structures of the urinary tract were different. In addition, in our experimental study the urethral wall was already strictured, in contrast with the normal tissue of the ureter of porcine models in the previous mentioned experiment. Liatsikos et al. pre- sented an experimental study for the comparison of the efficacy of standard bare metal stents and PTX-coated metal stents in the ureteral wall of porcine models (21). Ten standard stents were placed randomly in the right or left ureter of 10 female pigs and ten PTX-coated stents placed in the other ureter of the same porcine models. After a follow-up period of 21 days all experimental mod- els were sacrificed. After the histological evaluation, they concluded that PTX-coated stents contributed to less inflammation and hyperplasia of the ureteral wall com- pared to standard stents. Another important study about the effect of PTX-coated stents in the ureteral tissue’s hyperplasia was presented by Kram et al. (22). They com- pared the efficacy of uncoated polyurethane stents and PTX-coated stents in a rat ureteral model after the con- duction of ureteroureterostomy. Their outcomes indicat- ed that PTX contributed to decreasing hyperplastic pro- liferation and postoperative restenosis rate. Consequently, PTX-coated balloons or stents may be a promising approach for the management of strictures even in the upper or in the lower urinary tract. A plethora of drugs has been tested regarding the efficacy in the restenosis formation of the urothelial lumen, such as poly-DL-lactic acid, zotarolimus, captopril, halofugi- none, protein nanofilm-controlled drugs, rapamycin, insulin-like growth factors, Clostiridium histolyticum and others (23-26). However, only PTX proved its feasibility both in experimental and clinical aspects. Virasoro et al. presented a prospective, multi-center, clinical study about the usage of Optilume® PTX-coated balloon (Laborie Medical Technologies, Mississauga, Ontario, Canada) for the Archivio Italiano di Urologia e Andrologia 2024; 96(1):12248 K. Pagonis, A. Peteinaris, C. Adamou, et al. 6 management of patients with urethral stricture (27). The follow-up of the patients lasted 3 years and included the measurement of IPSS score, maximum flow rate, post-void residual urine volume and the evaluation of erectile func- tion. All parameters of the study were improved after the intervention with PTX-coated balloons in most of the par- ticipants and there was no influence in the sexual function of the patients. Elliott and colleagues prepared a random- ized controlled trial where 127 patients separated in 2 groups (28). First group included patients treated by Optilume® PTX-coated balloon and second group patients treated by urethral dilation or optical internal urethroto- my. After 6 months they evaluated the anatomic success by a simple passage of a flexible cystoscope. 1 year after the primal intervention they measured the IPSS score and the maximum flow rate in all participants. They, also, investigated in which of the participants a repeated inter- vention was necessary. All results of the study were in favor of Optilume® PTX-coated balloon group except of minor complications, such as minor hematuria and dysuria which were observed more frequently in patients treated by PTX-coated balloons. There are some limitations related to our experimental trial which should be mentioned. First of all, human anatomy and tissue differs from the experimental rabbit’s model that was used in the current experimental study. Moreover, the follow up period of the models lasted until only six weeks. Longer-term outcomes are needed for the evaluation of the distribution of PTX in different layers of the urethral wall. In the current study, we have some clues about the efficacy of DCBs in the treatment of stric- tured urethral lumen as we evaluated the inflammation and fibrosis of the strictured rabbit‘s urethras. Nonetheless, it is not possible to do flow studies to the rabbits to obtain more information on the efficacy of the approach. CONCLUSIONS PTX-coated balloons seem to be an effective approach for the treatment of urethral stenosis. When PTX was released in the strictured rabbit’s urethra, its distribution included all layers of the urethral wall and most impor- tantly the smooth muscle layer, which related to the fibrosis and the restenosis of the lumen. The results showed reduced inflammation and fibrosis. Consequently, DCBs may play an important inhibitive role in the restenosis formation. REFERENCES 1. Jacobs ME, de Kemp VF, Albersen M, et al. The use of local ther- apy in preventing urethral strictures: A systematic review. PloS one 2021; 16:e0258256. 2. Pang KH, Chapple CR, Chatters R, et al. A Systematic Review and Meta-analysis of Adjuncts to Minimally Invasive Treatment of Urethral Stricture in Men. Eurn Urol 2021; 80:467-479. 3. Tepe G, Brodmann M, Micari A, et al. 5-Year Outcomes of Drug- Coated Balloons for Peripheral Artery In-Stent Restenosis, Long Lesions, and CTOs. JACC: Cardiovas Interv 2023; 16:1065-1078. 4. Will TA, Polcari AJ, Garcia JG, et al. Paclitaxel inhibits ureteral smooth muscle cell proliferation and collagen production in the absence of cell toxicity. J Urol 2011; 185:335-340. 5. Lee C-H, Hsieh M-J, Liu S-C, et al. Novel bifurcation stents coat- ed with bioabsorbable nanofibers with extended and controlled release of rosuvastatin and paclitaxel. Mater Sci Eng C Mater Biol Appl. 2018; 88:61-69. 6. Liu L, Lan X, Chen X, et al. Multi-functional plant flavonoids reg- ulate pathological microenvironments for vascular stent surface engi- neering. Acta Biomater 2023; 157:655-669. 7. Chen N, Guo D, Guo Y, et al. Paclitaxel inhibits cell proliferation and collagen lattice contraction via TGF-β signaling pathway in human tenon's fibroblasts in vitro. Eur J Pharmacol 2016; 777:33- 40. 8. Choritz L, Grub J, Wegner M, et al. Paclitaxel inhibits growth, migration and collagen production of human Tenon's fibroblasts— potential use in drug-eluting glaucoma drainage devices. Graefes Arch Clin Exp Ophthalmol. 2010; 248:197-206. 9. Barbalias D, Lappas G, Ravazoula P, et al. Evaluation of the Distribution of Paclitaxel After Application of a Paclitaxel-Coated Balloon in the Rabbit Urethra. J Endourol 2018; 32:381-386. 10. Nakada SY, Soble JJ, Gardner SM, et al. Comparison of acucise endopyelotomy and endoballoon rupture for management of second- ary proximal ureteral stricture in the porcine model. J Endourol 1996; 10:311-318. 11. Parwani D, Ahmed MA, Mahawar A, et al. Peripheral Arterial Disease: A Narrative Review. Cureus 2023; 15:e40267. 12. Sharma N, Finn MT, Parikh SA, et al. The Ranger drug-coated balloon: advances in drug-coated technology for treatment of femoropopliteal segment arterial disease. Future Cardiol 2023; 19:127-135.. 13. Kulyassa P, Engh MA, Vámosi P, et al. Drug-coated balloon ther- apy is more effective in treating late drug-eluting stent in-stent restenosis than the early occurring one-a systematic review and meta-analysis. Front Cardiovasc Med. 2023; 10:1062130. 14. Byrne RA, Joner M, Alfonso F, et al. Drug-coated balloon thera- py in coronary and peripheral artery disease. Nat Rev Cardiol 2014; 11:13-23. 15. Kar S. Outcomes of New-Generation Drug-Eluting Stents in Women with Acute Myocardial Infarction. Cur Cardiol Rep 2019; 21:2. 16. Woolford S, Tran M, Yoda C, et al. Studying the effect of drug- to-excipient ratio on drug release profile for drug coated balloons. Int J Pharm 2022; 620:121749. 17. Kallidonis P, Adamou C, Castillo SV, et al. Drug-delivering devices in the urinary tract: A systematic review. Arab J Urol 2021; 19:191-204. 18. Fu D, Chong T, Li H, et al. Docetaxel inhibits urethral stricture formation, an initial study in rabbit model. PloS one 2014; 9:e112097. 19. Shin JH, Song HY, Choi CG, et al. Tissue hyperplasia: influence of a paclitaxel-eluting covered stent--preliminary study in a canine urethral model. Radiology 2005; 234:438-444. 20. Liourdi D, Kallidonis P, Kyriazis I, et al. Evaluation of the dis- tribution of Paclitaxel by immunohistochemistry and nuclear mag- netic resonance spectroscopy after the application of a drug-eluting balloon in the porcine ureter. J Endourol 2015; 29:580-589. 21. Liatsikos EN, Karnabatidis D, Kagadis GC, et al. Application of Archivio Italiano di Urologia e Andrologia 2024; 96(1):12248 7 Paclitaxel coated balloon for urethral stricture paclitaxel-eluting metal mesh stents within the pig ureter: an experi- mental study. Eur Urol 2007; 51: 217-223. 22. Kram W, Rebl H, Wyrwa R, et al. Paclitaxel-coated stents to pre- vent hyperplastic proliferation of ureteral tissue: from in vitro to in vivo. Urolithiasis 2020; 48:47-56. 23. Han K, Park JH, Yang SG, et al. EW-7197 eluting nano-fiber covered self-expandable metallic stent to prevent granulation tissue formation in a canine urethral model. PloS one 2018; 13:e0192430. 24. Kotsar A, Nieminen R, Isotalo T, et al. Biocompatibility of new drug-eluting biodegradable urethral stent materials. Urology 2010; 75:229-234. 25. Sangkum P, Yafi FA, Kim H, et al. Collagenase Clostridium his- tolyticum (Xiaflex) for the Treatment of Urethral Stricture Disease in a Rat Model of Urethral Fibrosis. Urology 2015; 86:647.e641-646. 26. Kallidonis P, Kitrou P, Karnabatidis D, et al. Evaluation of zotarolimus-eluting metal stent in animal ureters. J Endourol 2011; 25:1661-1667. 27. Virasoro R, DeLong JM, Estrella RE, et al. A Drug-Coated Balloon Treatment for Urethral Stricture Disease: Three-Year Results from the ROBUST I Study. Res Rep Urol 2022; 14:177-183. 28. Elliott SP, Coutinho K, Robertson KJ, et al. One-Year Results for the ROBUST III Randomized Controlled Trial Evaluating the Optilume(®) Drug-Coated Balloon for Anterior Urethral Strictures. J Urol 2022; 207:866-875. Correspondence Konstantinos Pagonis, MD (Corresponding Author) pagonisk7@gmail.com Angelis Peteinaris, MD peteinarisaggelis@gmail.com Constantinos Adamou, MD constantinos.adamou@live.com Vasileios Tatanis, MD tatanisbas@gmail.com Athanasios Vagionis, MD thanos_vagionis@hotmail.gr Anastasios Natsos, MD a.natsos@gmail.com Mohammed Obaidat, MD kasious.klay@gmail.com Solon Faitatziadis, MD solonasfait@gmail.com Panagiotis Kallidonis, MD pkallidonis@yahoo.com Department of Urology, University Hospital of Rion, Patras, Greece Evangelos Liatsikos, MD liatsikos@yahoo.com Department of Urology, University Hospital of Rion, Patras, Greece Medical University of Vienna, Vienna, Austria Conflict of interest: The authors declare no potential conflict of interest.