Preclinical development of a novel sildenafil analogue

1. Preclinical development of a novel sildenafil analogue www.gdenucci.com Email - denucci@gdenucci.com

2. Regular Drug Development Process (Steps from Test Tube to New Drug Application Review) Pre-clinical Research Clinical Studies NDA Review Phase 1 Phase 2 Synthesis and Purification Phase 3 Accelerated Development / Review Animal Testing Treatment Ind Short Term Parallel Track Long Term Institutional Review Boards Sponsor/FDA Meetings encouraged Sponsor answers any question concerning the study and/or results Industry Time IRB

3. Metabolization of Sildenafil by CYP3A4 and CYP2C9 resulting in formation of N-desmethylsildenafil. CYP3A4 and CYP2C9 The desmethyl derivative possesses approximately 50% of the activity of the parent molecule.

4. Hydroxyethylsildenafil (H) Desmethylsildenafil (D) Sildenafil

5. Carbonate H H Urea Urethane D D H D

6. EFFECTS OF SILDENAFIL ANALOGUES IN HUMAN CORPUS CAVERNOSUM

7. Organ bath • Dissection of the corpora cavernosa; • 10-ml organ baths; • CC precontracted with PE (10 µM), following equilibration.

8. Potency of sildenafil and its derivatives in HCC EC50 carbonate: 0.40  0.17 mM EC50 urea: 12.56  1.92 mM EC50 urethane: 11.66  1.58 mM EC50 sildenafil: 0.38  0.16 mM EC50 hydroxyethylsildenafil: 0.26  0.15 mM EC50 desmethylsildenafil: 1.26  0.12 mM

9. Comparison of Potency and Half-Maximal Effective Concentration (EC50) to Sildenafil and Its Derivatives in Rabbit and Human Corpus Cavernosum. Rabbit Human Agent Agent EC (µM) E EC (µM) E 50 max 50 max Sildenafil Sildenafil ± ± 0.379 0.157 106.8 8.2 ± ± 1.29 0.11 105.2 5.5 ± 1.36 0.10 101.9 1.1 ± Hydroxyethylsild Hydroxyethylsild ± ± 110.0 9.0 0.259 0.147 Carbonate Dimer ± 1.255 0.122 ± 88.3 7.5 0.81 0.15 102.6 1.3 ± ± Desmemethylsild Urethane Dimer ± 0.402 0.168 ± 99.6 8.0 ± 2.40 0.15 78.9 6.2 Carbonate Dimer ± Urea Dimer ± ± 2.76 0.14 93.4 1.1 ± ± Urethane Dimer 11.660 1.578 69.2 9.6 ± ± Urea Dimer 12.561 1.921 65.5 5.5

10. STABILITY AND METABOLIZATION OF SILDENAFIL DIMERS IN RAT, DOG AND HUMAN PLASMA

11. Chromatograms 0.4 0.4 Volts Volts 0.2 0.2 0.0 0.0 0 1 2 3 4 5 6 7 8 9 10 Minutes A) Plasma Blank B) Plasma+ standards 10 mg/mL Hydroxyethyl - Sildenafil Urea dimer sildenafil Urethane Carbonate dimer dimer Desmethyl - sildenafil Gradient artefact/blank effect Note that the urea dimer apparently contains an “impurity”.

12. Urea Dimer D D

13. Urea dimer after 2h of incubation at 37°C A) Rat Plasma B) Dog Plasma C) Human Plasma

14. Urethane Dimer H D

15. Urethane dimer after 2h of incubation at 37°C A) Rat Plasma B) Dog Plasma C) Human Plasma

16. Carbonate Dimer H H

17. Carbonate dimer after 2h of incubation at 37°C A) Rat Plasma B) Dog Plasma C) Human Plasma

18. Dimers after 2h of incubation with rat microsomes at 37°C Urea Dimer Urea O min. O min. O min. Blank 5 min. 5 min. 5 min. 3O min. 3O min. 3O min. Urethane Dimer Urethane Blank Carbonate Dimer Carbonate Blank Hydroxyethyl-sildenafil ? Desmethyl-sildenafil ? Blank or impurity A) Urea Dimer B) Urethane Dimer C) Carbonate Dimer

19. Urethane Dimer Desmethyl-sildenafil ? Hydroxyethyl-sildenafil ? Urea Dimer Desmethyl-sildenafil ? ?? Carbonate Dimer Desmethyl-sildenafil? Hydroxyethyl-sildenafil Carbonate dimer ?? Dimers after 2h of incubation with rat hepatocytes at 37°C A) Urea Dimer B) Urethane Dimer C) Carbonate Dimer

20. PHARMACOKINETICS OF SILDENAFIL DIMERS IN CONSCIOUS BEAGLES DOGS (I.V. ADMINISTRATION)

21. Sildenafil, desmethylsildenafil and hydroxyethylsildenafil concentration following bolus injection (1mg/kg i.v.) in beagles

22. 2000 Sildenafil Concentration (ng/ml) 1000 Hydroxyethylsildenafil 0 0 1 2 3 4 5 6 7 8 9 10 11 12 Time (h) Sildenafil x Hydroxyethylsildenafil and Sildenafil X Desmethylsildenafil concentration following bolus injection (1mg/kg i.v.) in beagles

23. Urethane Dimer and desmethylsildenafil concentration following urethane (1mg/kg i.v.) in beagles

24. 500 Hydroxyethylsildenafil (ng/ml) 250 0 0 1 2 3 4 5 6 7 8 9 10 11 12 Time (h) Carbonate Dimer, hydroxyethylsildenafil and desmethylsildenafil concentration following carbonate (1mg/kg i.v.) in beagles

25. PHARMACOKINETICS OF SILDENAFIL DIMERS IN BEAGLES DOGS (ORAL ADMINISTRATION)

26. Carbonate and hydroxyethylsildenafil concentration following carbonate dimer(100mg/animal; oral dose) in beagles

27. Hydroxyethylsildenafil concentrationfollowing sildenafil, hydroxyethylsildenafil and carbonate dimer (100mg/animal; oral dose) in beagles

28. Pharmacokinetics of sildenafil, hydroxyethylsildenafil, carbonate dimer and hydroxyethylsildenafil metabolite (after carbonate) in beagles

29. 1.5 1.0 0.5 0.0 Hydroxy (after carbonate) Sildenafil Hydroxyethylsildenafil Carbonate Dimer Absolute bioavaliability of sildenafil, hydroxyethylsildenafil, carbonate dimer and hydroxyethylsildenafil metabolite (after carbonate) in beagles 1.38 1.31 0.83 0.004

30. ORAL ADMINISTRATION OF SILDENAFIL AND LIFAFIL ON MEAN ARTERIAL BLOOD PRESSURE IN MALE WISTAR RATS USING TELEMETRY SYSTEM

31. Methods • Implant of radiotelemetry device into descending aorta; • Mean Arterial Blood Pressure (MABP) acquired twice a week for 90 seconds during 8 weeks;

33. Effect in MABP induced by gavage administration of Sildenafil and CRIS31 (1 mg/rat)

34. Effect in MABP induced by gavage administration of Sildenafil and CRIS031 (3 mg/animal)

35. Effect in MABP induced by gavage administration of Sildenafil and CRIS031 (10mg/rat)

36. CONCLUSION • No significant change on arterial blood pressure was observed using Sildenafil or CRIS031 (1, 3 or 10 mg/rat) by gavage administration using telemetry system.

37. EFFECT OF ENDOVENOUS COMPOUND ADMINISTRATION ON THE ARTERIAL PRESSURE AND HEART RATE IN ANAESTHETIZED BEAGLE DOGS

38. Experimental Design • - Male dogs (n=9) anaesthetized with Hypnol, 30 mg/kg, i.v. • Entubated and ventilated with room air (FiO2=21%). • Left femoral artery (systemic arterial blood pressure) • Left femoral vein (drug administration) • Heart rate and ECG acquisitions

39. R P T Q S Electrocardiogram P wave – atrial depolarization. QRS waves – ventricular depolarization. Q wave - first negative deflection R wave - first positive deflection S wave - negative deflection after R wave T wave – ventricular repolarization

40. No significant electrocardiogram change was observed • Experimental Protocol • 3 animals each compound in ascending doses • Sildenafil (1mg/kg/5min) plus 20 min standby • Sildenafil (3mg/kg/5min) plus 20 min standby • Sildenafil (10mg/kg/5min) plus 20 min standby • Carbonate (1mg/kg/5min) plus 20 min standby • Carbonate (3mg/kg/5min) plus 20 min standby • Carbonate (10mg/kg/5min) plus 20 min standby • Hydroethylsildenafil (1mg/kg/5min) plus 20 min standby • Hydroethylsildenafil (3mg/kg/5min) plus 20 min standby • Hydroethylsildenafil (10mg/kg/5min) plus 20 min standby • OBS: All compounds were dissolved in DMSO 100%

41. Effect of Sildenafil administration on arterial pressure 150 100 (mmHg) Arterial Pressure Before After 50 0 1mg/kg 3mg/kg 10mg/kg

42. Effect of Hydroxyethylsildenafil administration on arterial pressure 150 100 Arterial Pressure (mmHg) Before After 50 0 1mg/kg 3mg/kg 10mg/kg

43. Effect of Carbonate dimer administration on arterial pressure 150 100 (mmHg) Arterial Pressure Before After 50 0 1mg/kg 3mg/kg 10mg/kg

44. Effect of Sildenafil administration on heart rate 200 150 Before HR (beats/min) 100 1.5 min after 3.0 min after 50 5.0 min after 0 1mg/kg 3mg/kg 10mg/kg

45. Effect of Hydroxyethylsildenafil administration on heart rate 200 150 Before HR (beats/min) 100 1.5 min after 3.0 min after 50 5.0 min after 0 1mg/kg 3mg/kg 10mg/kg

46. Effect of Carbonate dimer administration on heart rate 200 150 HR (beats/min) Before 100 1.5 min after 3.0 min after 50 5.0 min after 0 1mg/kg 3mg/kg 10mg/kg

47. CONCLUSION • Based on the mentioned results, we have decided that the hydroxyethylsildenafil dimer (the carbonate dimer) was more suitable for pre-clinical development.

48. Pre-clinical Test - Phase I • in vitro – mutagenic activity (Ames´ test) • in vivo – two animal species, one rodent (rat) and one non rodent (dog) for 2 weeks

49. EVALUATION OF THE MUTAGENIC ACTIVITY OF CRIS031 IN SEVERAL Salmonella typhimurium STRAINS USING STANDARD AMES TEST

50. Ames Test (Salmonella typhimurium) • Bacterial reverse mutation assays are widely used to evaluate the mutagenic potential of chemicals, formulations, or extracts. The most common assay involves the use of amino acid-requiring strains of Salmonella typhimurium and is commonly referred to as the "Ames Test". • In the absence of an external amino acid source (histidine for Salmonella), the cells cannot grow to form colonies unless a reversion of the mutation allows the synthesis of the amino acid to resume. •  Spontaneous reversions occur with each of the strains. However, some compounds induce a mutagenic response and thereby increase the number of revertant colonies substantially over the spontaneous reversion level.