MEDICAL DEVICES HAVING AN IMMEDIATELY DETACHABLE, PERMANENTLY PROLIFERATION-INHIBITING COATING COMPRISING AT LEAST ONE LIMUS SUBSTANCE AND METHOD OF PRODUCTION

Abstract

In order to provide medical devices having a coating for local prophylaxis and treatment of undesirable cell proliferation and vasoconstriction, a medical device comprising a coating on at least a portion of the surface is proposed, said coating comprising at least one limus substance in non-encapsulated crystalline form, wherein the at least one non-encapsulated limus substance is applied directly from a solvent mixture of at least one organic solvent and water. The formation of crystals of the limus substance can be brought about or enhanced by slowing down the evaporation of the solvent mixture.

In addition, a method for preparing the medical devices is proposed.

Claims

1-15. (canceled)

16. A medical device, comprising a coating on at least a portion of the surface thereof, wherein the coating comprises at least one limus substance in non-encapsulated crystalline form, and wherein the at least one crystalline non-encapsulated limus substance: i) was applied directly from a solution containing a water-miscible organic solvent or a mixture of water-miscible organic solvents and water; or ii) was applied as a suspension consisting of a water-miscible organic solvent mixture or a mixture of water-miscible organic solvents and water, optionally, drying of the at least one limus substance applied as a solution according to (i) or suspension according to (ii) was slowed down or restricted, and wherein, further, the organic solvent is selected from a group consisting of methanol, ethanol, isopropanol, tetrahydrofuran, acetic acid and/or acetone.

17. The medical device according to claim 16, characterized in that the optional drying was carried out, and said drying was performed by pulling over a pipe or tube.

18. The medical device according to claim 16, characterized in that the coating further comprises one or more antioxidants selected from the following group: ascorbyl palmitate, butylated hydroxyanisole, butylated hydroxytoluene, nordihydroguaiaretic acid, probucol, propyl gallate, and resveratrol.

19. The medical device according to claim 16, characterized in that the coating further comprises one or more excipients and/or additives.

20. The medical device according to claim 19, characterized in that the excipients are antioxidants in proportions of >5 wt % of the limus substance.

21. The medical device according to claim 19, characterized in that the excipients are fatty acid salts in the range of 0.5-50 wt % of the limus substance.

22. The medical device according to claim 16, characterized in that a further layer comprising one or more excipients and/or additives is applied.

23. The medical device according to claim 22, characterized in that the excipients are antioxidants in proportions of >5 wt % of the limus substance.

24. The medical device according to claim 22, characterized in that the excipients are fatty acid salts in the range of 0.5-50 wt % of the limus substance.

25. The medical device according to claim 16, characterized in that the medical device is an angioplasty balloon catheter, an indwelling catheter, or a stent.

26. The medical device according to claim 16, wherein said at least one limus substance is selected from Sirolimus, everolimus, zotarolimus, and biolimus.

27. A method for coating at least a portion of the surface of a medical device with at least one crystalline limus substance, said comprising: a) dissolving or suspending at least one limus substance in at least one water-miscible organic solvent and water to form a supersaturated solution or to maintain true solubility, followed by either: b1) applying the supersaturated solution or the true solution to the surface of the medical device, and crystallizing; or b2) applying the suspension to the balloon surface; and c) drying.

28. The method according to claim 27, characterized in that the drying according to c) is slowed down.

29. The method according to claim 28, characterized in that the drying c) is slowed down by placing the medical device in a pipe or tube, by restricting air exchange, by a low temperature and/or by the composition of the gas phase in the environment of the medical device.

30. The method according to claim 27, characterized in that, in a final step d), at least one additional layer of an additive/excipient is applied.

31. The method according to claim 27, characterized in that, in addition to the at least one limus substance, one or more antioxidants are applied.

32. The method according to claim 31, wherein said one or more antioxidants is/are selected: ascorbyl palmitate, butylated hydroxyanisole, butylated hydroxytoluene, nordihydroguaiaretic acid, probucol, propyl gallate, and/or resveratrol.

33. The method according to claim 27, wherein said at least one limus substance is selected from Sirolimus, everolimus, zotarolimus, and biolimus.

Description

EXAMPLE 1

[0075] (1) Provision of Sirolimus Crystals

[0076] 200 mg of sirolimus was dissolved in 2 ml of ethyl acetate; to this solution, 2.5 ml of hexane was added in 0.5 ml portions and mixed. A clear solution was obtained, which was first cooled to −20° C. in the freezer for 10 minutes. Crystallization was initiated by 30 min of ultrasonication, with simultaneous ice cooling.

[0077] The sample was stored overnight at −20° C. and then centrifuged at −9° C., and the supernatant was decanted.

[0078] The sediment consisting of sirolimus crystals was dried in vacuo.

[0079] (2) Coating Preparation

[0080] 50 mg of the dry crystals thus produced were placed in 1 ml of a solution containing 5 mg/ml of dexpanthenol and 6.5 mg/ml of butylated hydroxytoluene in acetone/water 1:1 (v/v) and mixed. A suspension was obtained.

[0081] (3) Coating

[0082] Catheter: PTCA, rapid exchange, Creganna, balloon size 3.5×20 mm, inflated, is coated with the suspension.

[0083] Sirolimus content/balloon=5.8±0.7 μg/mm.sup.2=1469±189 μg

EXAMPLE 2

[0084] (1) Provision of Sirolimus Crystals

[0085] 500 mg of sirolimus was dissolved in 5 ml of ethyl acetate. To the solution, 6.25 ml of n-hexane was added in 2 ml portions and mixed after each portion. The solution remained clear. To form crystals, the solution was first stored at −20° C. for 10 minutes and ultrasonicated for 30 minutes while being ice-cooled and was then left at −20° C. overnight and centrifuged at −9° C. The supernatant was transferred to another vessel. The sirolimus crystals were dried in vacuo.

[0086] (2) Coating Preparations

[0087] These crystals were used to prepare the following preparations for coating medical devices:

TABLE-US-00002 Name of preparation Composition of the preparations RFlimus-Q-50- 50 mg/ml of sirolimus + 5 mg/ml DP-5-BHT-0.5 of dexpanthenol, +0.5 mg/ml butylated hydroxytoluene in ethanol, water 60/40 (v/v) RFlimus-S-50- 50 mg/ml of sirolimus + 5 mg/ml of DP-5-BHT-0.5 dexpanthenol, +0.5 mg/ml of BHT in methanol, water 70/30 (v/v)

[0088] (3) Coating

[0089] A temporary spur stent system (2.sup.nd generation) from ReFlow medical Inc. (San Clemente, USA) was coated

TABLE-US-00003 Coating SIR SIR Sample Size preparation *(μg) **(μg/mm.sup.2) Coated balloon 4.0 × 80 mm RFlimus-Q-50- 2862 ± 67 2.85 ± 0.07 DP-5-BHT-0.5 Coated spur (stent with 4.0 × 60 mm RFlimus-Q-50- 1297 ± 84 8.7 ± 0.6 outwardly directed DP-5-BHT-0.5 projections, see FIG. 1) Coated balloon 4.0 × 80 mm RFlimus-S-50- 2693 ± 23 2.68 ± 0.02 DP-5-BHT-0.5 Coated spur (stent with 4.0 × 60 mm RFlimus-S-50-  1396 ± 232 9.4 ± 1.6 outwardly directed DP-5-BHT-0.5 projections, see FIG. 1) *after delivery from the delivery catheter **cylindrical surface, vessel wall coverage

[0090] A spur (stent) coated with RFlimus-Q-50-DP-5-BHT-0.5 is shown in FIG. 1.

EXAMPLE 3

[0091] Comparison of 3 coatings according to the invention with samples of a commercial product (Magic Touch).

TABLE-US-00004 TABLE 2 Test sample (SIR = sirolimus, BHT = butylated hydroxytoluene, THF = tetrahydrofuran): Balloon size [mm] Balloon Balloon surface Volume/ SIR catheter, area Composition of the balloon Solution/ SIR (μg/ Label type [mm.sup.2] coating preparation [μl] suspension (μg) mm.sup.2) A2 3.5 × 20 255 40 mg/ml of SIR + 28 Solution 1020 4 Creganna 1 mg/ml of Mg 2 × 14 stearate + 0.4 mg/ml of BHT (THF, acetone, water, acetic acid 19.5/40/40.05/0.45) C2 3.5 × 20 255 40 mg/ml of SRL + 31 Suspension 1020 4 Creganna 0.4 mg/ml of BHT (methanol, water 70/30) C3 3.5 × 20 255 40 mg/ml of SRL + 62 Suspension 2040 8 Creganna 0.4 mg/ml of BHT (methanol, water 70/30) MT 3.5 × 20 255 ‘Nanolute’ - ? Liposomal ~320 1.25 Magic sirolimus-coated preparation Touch ™* ? *Cortese B, et al, Immediate and short-term performance of a novel sirolimus-coated balloon during complex percutaneous coronary interventions. Cardiovasc Revasc Med (2017), http://dx.doi.org/10.1016/j.carrev.2017.03.025

[0092] Preparation of the coating solution/suspensions:

[0093] Preparation of the Solution for A2 Coating

[0094] A solvent mixture of 3.9 ml of tetrahydrofuran, 8.0 ml of acetone and 90 μl of acetic acid was prepared. In 9.0 ml of the mixture, 6 mg of butylated hydroxytoluene (BHT) was dissolved. 6 mg of magnesium stearate was dissolved in 3.6 ml of BHT solution. To this solution, 2.4 ml of water was added, which was ultrasonicated for 10 minutes. 40 mg of sirolimus was then dissolved in 1 ml of the BHT/magnesium stearate solution.

[0095] Preparation of the Suspension for Coating C2 and C3

[0096] The sirolimus crystals were provided as described in Example 2.

[0097] In 15 ml methanol/water (70/30, v/v), 6 mg of BHT was dissolved (0.4 mg/ml), and 40 mg of SIR/ml was suspended therein.

[0098] Coating of A2:

[0099] With the folded balloons rotating continuously about the longitudinal axis, 14 μl of the solution was applied twice to the balloons with a period of approximately 30 minutes in between.

[0100] Immediately after the coating, wide (inner diameter of 1.3 mm) protective covers were pulled over the balloons.

[0101] After 16 hours, the wide protective covers were replaced with narrow protective covers (inner diameter of 1.1 mm).

[0102] Coating of C2 and C3:

[0103] A protective cover with an inner diameter of approximately 1.2 mm was pushed beyond the uncoated, still folded balloon onto the catheter shaft.

[0104] The balloons were inflated immediately before coating.

[0105] The suspension was applied to the balloons rotating about the longitudinal axis.

[0106] The rotation of the balloons was then continued for 1 minute to allow the coating to dry.

[0107] The balloons were then deflated using a vacuum, and the protective covers were pulled back over the coated balloons, with the balloon membranes being folded again.

EXAMPLE 4

[0108] Variations of Coating A2

[0109] Preparation of the solution for coating modifications A2a, A2b, A2c, A2d, A2e:

[0110] A solvent mixture of 3.9 ml of tetrahydrofuran, 8.0 ml of acetone and 90 μl of acetic acid was prepared. In 9.0 ml of the mixture, 6 mg of butylated hydroxytoluene (BHT) was dissolved. 6 mg of magnesium stearate was dissolved in 3.6 ml of BHT solution. To this solution, 2.4 ml of water was added, which was ultrasonicated for 10 minutes. 40 mg of sirolimus was then dissolved in 1 ml of the BHT/magnesium stearate solution.

[0111] Preparation of the solution for coating modifications A3b and A3e

[0112] A solvent mixture of 3.9 ml of tetrahydrofuran, 8.0 ml of acetone and 90 μl of acetic acid was prepared. In 10.3 ml of the mixture, 6 mg of butylated hydroxytoluene (BHT) was dissolved. 5.25 mg of magnesium stearate was dissolved in 3.6 ml of BHT solution. To this solution, 2.4 ml of water was added, which was ultrasonicated for 10 minutes. 40 mg of sirolimus was then dissolved in 1 ml of the BHT/magnesium stearate solution.

[0113] Modification of the Coating Method:

TABLE-US-00005 Variation Composition Coating process A2 40 mg/ml of SRL + The folded balloon was coated with a manual Hamilton 1 mg/ml of Mg stearate + syringe while being rotated. The coating solution was 0.4 mg/ml of BHT divided into two portions. The second portion was (THF, acetone, water, acetic acid applied after the first had dried. A wide-lumen 19.5/40/40.05/0.45) protective cover was immediately pulled over the still wet coating. After the coating had been dried for 12 to 24 hours, the wide protective cover was replaced with a protective cover with a narrower lumen. A2a Coating in 2 portions First portion: The inflated balloon was coated with a manual Hamilton syringe while being rotated, dried for 5 minutes and then folded by applying a vacuum. Second portion: Process the same as for A2. A2b The balloon was first inflated before coating and then folded back again so that the folds were perpendicular to the shaft. Otherwise the process is the same as for A2. A2c The coating was applied with a portion of coating solution. The balloon was inflated and coated while being rotated. The balloon was then refolded in a vacuum, and a wide protective cover was pulled over. Otherwise the same as process for A2 A2d Process the same as for A2b, but the coating was applied with an automatic dispensing system. A2e The coating was applied with a portion of coating solution. The balloon was first inflated and coated while being rotated. After dispensing the first half of the coating solution, the pressure was released from the balloon while the distribution of the coating solution continued. After the coating was finished, a vacuum was immediately applied and a wide protective cover was pulled over the coating, which was still wet. Otherwise the same as process for A2 A3b 35 mg/ml of SRL + Process the same as for A2b, but the coating was 0.875 mg/ml of Mg stearate + applied with an automatic dispensing system. A3e 0.35 mg/ml of BHT Process the same as for A2e (THF, acetone, water, acetic acid 19.5/40/40.05/0.45)

[0114] The results of the analysis of the modifications are set out in Table 1 under Example 5

EXAMPLE 5

[0115] Differences in the dissolution rate of sirolimus in an aqueous medium

[0116] For the composition of the coating preparations, see Table 4 (A1, A2, B1 and D1, columns 2-4; the preparations for C1 and C2 contained crystals according to Example 1, paragraph 1).

[0117] Coating:

[0118] Before the balloons of groups A1, B1, C1 and D1 were inflated and coated, protective covers with an inner diameter of 1.05 mm were pulled over from the distal region to the proximal region of the balloon shaft. The balloons in question were inflated and coated with the preparations set out in Table 4 with Hamilton microsyringes while being continuously rotated.

[0119] After being coated, the balloons were deflated and the protective covers were carefully pulled in the distal direction, with the balloon membranes having been folded back to their original state (before inflation and coating) and the folded balloons being completely covered by the protective covers.

[0120] The coating of groups A2 and C2 was carried out as described in Example 3.

[0121] Result

[0122] Table 4 shows [0123] (a) coating with a suitable dose (≥3 μg/mm.sup.2, column 6) with all coating variants, [0124] (b) that coating with limus crystals reduces the dissolution rate of the active ingredient (column 7), [0125] (c) that the transfer of the active ingredient onto or into the vessel wall was similar for all preparations (column 8), [0126] (d) that, in the case of the crystalline coating, a much higher drug concentration was found in the arterial tissue 4 weeks after treatment (column 9), [0127] (e) that, in the case of the A coatings, slowed-down drying of the solvents after coating reduces the dissolution rate of the active ingredient in an aqueous medium (column 6).

TABLE-US-00006 TABLE 4 Sirolimus (SIR) dissolution test, transfer to/into the vessel wall and indwelling time up to 4 weeks, for the abbreviations see Table 2 7 2 in-vitro SIR dissolution* Solution or 5 6 of 1.7 mg 8 9 10 crystal SIR on the SIR dose of SIR in SIR in the vessel wall after treatment** suspension 3 4 product by area 24 hours Minutes 4 weeks 1 [mg/ml] Additives Solvent mixture [μg] = dose [μg/mm.sup.2] [%] % of dose μg/g μg/g A1, not 40/ 1 mg/ml of THF, acetone, 957 ± 33 3.8 ± 0.1 98 ± 1 6.5 ± 4.0 187 ± 105 0.26 ± 0.07 fractionally solution Mg stearate water, acetic acid; coated, no 0.4 mg/ml of 19.5/40/40.05/0.45 protection BHT (v/v) against evaporation A2, 40/ 1 mg/ml of THF, acetone, 795 ± 48 3.1 ± 0.1 17 ± 2 fractionally solution Mg stearate water, acetic acid; coated, with 0.4 mg/ml of 19.5/40/40.05/0.45 protection BHT (v/v) against evaporation, see Example 3 A2a 40/ 1 mg/ml of THF, acetone, 790 3.1 29 ± 9 solution Mg stearate water, acetic acid; 0.4 mg/ml of 19.5/40/40.05/0.45 BHT (v/v) A2b 40/ 1 mg/ml of THF, acetone, 911 ± 37 3.6 ± 0.1 16 ± 1 2.7 ± 0.6 97 ± 20 24 ± 18 solution Mg stearate water, acetic acid; 0.4 mg/ml of 19.5/40/40.05/0.45 BHT (v/v) A2c 40/ 1 mg/ml of THF, acetone, 943 4   90 ± 2 solution Mg stearate water, acetic acid; 0.4 mg/ml of 19.5/40/40.05/0.45 BHT (v/v) A2d 40/ 1 mg/ml of THF, acetone,  872 ± 157 3.4 ± 0.6  62 ± 20 solution Mg stearate water, acetic acid; 0.4 mg/ml of 19.5/40/40.05/0.45 BHT (v/v) A2e 40/ 1 mg/ml of THF, acetone, 774 3.1 11 solution Mg stearate water, acetic acid; 0.4 mg/ml of 19.5/40/40.05/0.45 BHT (v/v) A3b 35/ 0.875 mg/ml of THF, acetone, solution Mg stearate water, acetic acid; 0.35 mg/ml of 19.5/40/40.05/0.45 BHT (v/v) A3e 35/ 0.875 mg/ml of THF, acetone, 851 ± 34 3.3 ± 0.1  9.2 ± 0.5 7.2 ± 4.0 188 ± 143 12 ± 11 solution Mg stearate water, acetic acid; 0.35 mg/ml of 19.5/40/40.05/0.45 BHT (v/v) B1 40/ 0.4 mg/ml of Acetone, ethanol, 932 ± 42 3.7 ± 0.2 97 ± 3 5.0 ± 4.2 132 ± 87  0.45 ± 0.34 solution BHT UV-370; 83/14/3 C1 50/ 5 mg/ml of Acetone, water 1469 ± 189 5.8 ± 0.7   11 ± 0.4 2.7 ± 4.2 160 ± 127 8.6 ± 4.1 suspension dexpanthenol 1/1 (v/v) 0.4 mg/ml of BHT C2 40/ 0.4 mg/ml of Methanol, water  878 ± 115 3.4 ± 0.5 32 ± 2 12.6 ± 4.3  347 ± 180 14 ± 25 suspension BHT 7/3 (v/v) D1 30/ 0.9 mg/ml of Acetone, water 1009 ± 14  4.0 ± 0.1   94 ± 0.4 4.8 ± 2.3 153 ± 84  0.36 ± 0.12 solution mannitol, 75/25 (v/v) 0.3 mg/ml of BHT *Coated products in 12 ml of an aqueous 5% (m/v) methyl-β-cyclodextrin (M-β-CD) MβCD solution (5% m/v), measuring the amount of sirolimus dissolved after centrifuging off undissolved components **For animal testing methodology, see Example 4 and Clever Y P, Peters D, Calisse J, Bettink S, Berg M-C, Sperling C, Stoever M, Cremers B, Kelsch B, Bohm M, Speck U, Scheller B. Novel Sirolimus-coated balloon catheter. In vivo evaluation in a porcine coronary model. Circ Cardiovasc Interv. 2016; 9: e003543. DOI: 10.1161/CIRCINTERVENTIONS.115.003543

EXAMPLE 6

[0128] Preparation and Testing of the Coating C2

[0129] For animal testing methodology, see Example 4 and Clever Y P, Peters D, Calisse J, Bettink S, Berg M-C, Sperling C, Stoever M, Cremers B, Kelsch B, Bohm M, Speck U, Scheller B. Novel Sirolimus-coated balloon catheter. In vivo evaluation in a porcine coronary model. Circ Cardiovasc Interv. 2016; 9:e003543.

[0130] DOI: 10.1161/CIRCINTERVENTIONS.115.003543

[0131] For provision of sirolimus crystals, see Example 2 For coating solution and results, see Table 5 Conclusion [0132] (a) Slowly soluble coating with crystals from an aqueous solvent possible (columns 5, 6, 8, 9, 10). [0133] (b) Slow dissolution of crystalline coating confirmed (column 7).

TABLE-US-00007 TABLE 5 Sirolimus (SIR) dissolution test, transfer onto/into the vessel wall and SIR on balloons after angioplasty, see Table 2 for abbreviations 8 7 SIR loss 9 5 6 in-vitro on the Transfer 10 SIR on SIR dissolution* simulated onto/into Remainder the dose by of 1.7 mg path to the vessel on balloon 2 3 4 balloon area of SIR in the lesion wall after use SIR Addi- Solvent [μg] = [μg/ 24 hours [% of [% of [% of 1 [mg/ml] tives mixture dose mm.sup.2] [%] dose] dose] dose] C2 a 40 0.5 Acetone, 829 3.2 27 15.8 ± 4.66 ± 15.7 ± Crystal- mg/ml methanol, 15.6 3.25 7.6 line of BHT water v/v: 41/25/34 *Coated products in 12 ml of an aqueous 5% (m/v) methyl-β-cyclodextrin (M-β-CD) MβCD solution (5% m/v), measured after centrifuging off undissolved components

EXAMPLE 7

[0134] Effect and Compatibility

[0135] Coronary arteries of 20 young domestic pigs were treated with sirolimus-coated catheters according to Examples 3 (A2) and Example 4 (C2). To enhance neointima proliferation caused by overexpansion of the arteries, all balloons were fitted with Coro Large cobalt/chromium stents from Fortimedix, The Netherlands, before sterilization. Immediately after treatment, the luminal diameter of the slightly overexpanded coronary vessel segments was measured, and the measurement was repeated after 4 weeks. The reduction in lumen diameter during the 4 weeks is termed “late lumen loss” (LLL) and characterizes the undesirable constriction of the vessels by neointima proliferation. The desired inhibition of neointima proliferation and thus the inhibition of the constriction of the treated arterial segments results, in part, from the difference in LLL between arteries treated with uncoated balloons and arteries treated with the sirolimus-coated balloons. The results can be found in Table 6.

TABLE-US-00008 TABLE 5 Coating solutions and volumes/balloon, see Table 2 for abbreviations Name of Composition of Volume/ coating the coating balloon Solution/ Group solution solutions [μl] suspension A2 Aco-SRL-A2 40 mg/ml of SIR + 2 × 14 Solution 1 mg/ml of Mg stearate + 0.4 mg/ml of BHT (THF, acetone, water, acetic acid 19.5/40/40.05/0.45, v/v) C2 Aco-SRL-C3 40 mg/ml of SIR + 31 Suspension 0.4 mg/ml of BHT (methanol, water 70/30)

TABLE-US-00009 TABLE 6 Inhibition of neointima proliferation/constriction of coronary artery lumen after angioplasty in pigs A2, C2 balloon coatings according to Table 5, U = uncoated Balloon catheter/coating A2 C2 U Number of balloon catheters/arteries n = 12 n = 12 n = 12 Sirolimus content [μg/mm.sup.2] 3.1 ± 0.2  3.5 ± 0.4 0 Quantitative coronary analysis (angiograms) Minimum arterial lumen diameter, 2.22 ± 0.24  2.28 ± 0.28 2.21 ± 0.31 segment before treatment [mm] Overexpansion due to stent implantation, 1.39 ± 0.12  1.27 ± 0.13 1.31 ± 0.13 ratio Minimum arterial lumen diameter 4 weeks 2.38 ± 0.24*  2.46 ± 0.23* 1.74 ± 0.57 after treatment [mm] LLL [mm] 0.67 ± 0.26*  0.60 ± 0.28* 1.14 ± 0.55 In-stent lumen diameter 21.6 ± 6.81* 16.62 ± 8.90* 39.7 ± 19.0 Stenosis in % of diameter after treatment and stent implantation Histomorphometry (microscopy) of arteries extracted 4 weeks after treatment Lumen, cross-sectional area (mm.sup.2) 4.91 ± 0.77*  4.73 ± 0.89* 3.11 ± 1.48 Lumen loss (cross-sectional area) 27.3 ± 8.8*  25.3 ± 8.0* 54.8 ± 18.1 % of area after stent implantation Lumen loss (diameter) 14 13 33  % of the diameter of the stent Neointima area [mm.sup.2] 1.85 ± 0.71*  1.60 ± 0.54* 3.54 ± 0.97 Stenosis area [%] 13.9 ± 4.5*  12.9 ± 4.0* 33.4 ± 14.4 *p < 0.01 versus uncoated

[0136] The animals did not show any clinically apparent signs of intolerance either acutely or during the 4-week observation period. ECG, blood pressure, angiography and histology confirmed the high level of tolerance of the coatings.