Ring-shaped devices

Abstract

The invention relates to a ring-shaped device comprising: (a) a first compartment comprising an non-medicated core of ethylenes˜vinylacetate copolymer, encircled by a steroid hormone loaded ethylene-vinylacetate copolymer layer, and a non-medicated outer layer of ethylene-vinylacetate copolymer; (b) a second compartment comprising a core of ethylene-vinylacetate copolymer loaded with a steroid hormone and a non-medicated outer layer of ethylene-vinylacetate polymer; and (c) optionally placebo segments of a thermoplastic material separating the first from the second compartment. Preferably, the invention is a two-compartment vaginal ring, the first compartment comprising crystalline etonogestrel and the second compartment comprising a (sub)-saturated mixture of etonogestrel and ethinyl estradiol, both compartments optionally being separated from each other by placebo segments of high density polyethylene.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of co-pending U.S. application Ser. No. 08/981,881, filed Dec. 31, 1997, now U.S. Pat. No. ______, which claims priority from PCT Patent Application No. PCT/EP 96/02935, filed July 1, 1996, and published, in English, on Jan. 23, 1997 as WO 97/02015 the contents of which are incorporated by this reference.

TECHNICAL FIELD

[0002] The invention relates generally to medical devices such as ring-shaped devices and to a method of manufacture the same. The invention relates, in particular, to ring-shaped vaginal devices, i.e., to vaginal rings.

BACKGROUND

[0003] Ring-shaped devices, and especially vaginal rings, are well known in the art. A two-layered one-compartment vaginal ring, for example, is disclosed in U.S. Pat. No. 4,237,885, in which a drug (progestational or estrogenic steroid) on a carrier is encircled by a polymeric tube, consisting of an ethylene-vinyl acetate copolymer, both ends of which are joined together with a solid polymeric plug. Devices of this type, however, do not provide acceptable release patterns. Improvement was sought by using other shapes or other materials. A two-layered one compartment vaginal ring made from silicone elastomer has been disclosed in European Patent Application EP 0,050,867, which ring comprises a silicone elastomer core loaded with active substance surrounded by a non-loaded silicone elastomer layer, which consists of two different compositions.

[0004] Another improvement was claimed in U.S. Pat. No. 4,292,965, which disclosed a three-layered one-compartment ring. This ring comprises an inert silicone elastomer core encircled by a medicated silicone layer, and a non-medicated silicone outer layer.

[0005] These above-mentioned one-compartment rings have the disadvantage that, when loaded with more than one active substance, release patterns of these substances can not be adjusted independently. Such devices usually show sub-optimum release patterns for the different substances, whereas it is generally preferred that all substances are released in a controlled rate and during a similar duration of time. As a consequence, the release ratio of the active substances undergoes a change after a period of time.

[0006] In an attempt to solve these problems a two-compartment vaginal ring was disclosed in U.S. Pat. No. 4,596,576. This device comprises two two-layered compartments, each containing another active substance. An advantage of this device is that the release ratio can be changed by changing the lengths of the compartments. To achieve a suitable ring with a constant release ratio, it is however necessary to join the ends of the compartments by using inert stoppers, which completely prevent mixing of the active ingredients. One of the disadvantages of this device is the relatively expensive and difficult method to join the compartment ends to the stoppers, which method can hardly be automated.

[0007] Apart from unfavorable release patterns, changing release ratios, and burst effects (excessive release in the first few days), which are frequently occurring with the known vaginal rings, most vaginal rings are prepared from silicone elastomer, which material is nowadays considered as less safe.

DISCLOSURE OF THE INVENTION

[0008] The present invention provides a ring-shaped device, with a good release pattern, preventing the disadvantages of the known vaginal rings, which can be manufactured in a simple automated manner. The invention also provides a ring-shaped device which, after introduction thereof into the vagina, releases the steroid hormones within a short time, preferably within one to two days, to reach the desired plasma levels.

[0009] It has been found that a ring-shaped device comprising:

[0010] (a) a first compartment comprising a non-medicated core of ethylene-vinylacetate copolymer, encircled by a steroid hormone loaded ethylene-vinylacetate copolymer middle layer, and a non-medicated outer layer of ethylene-vinylacetate copolymer;

[0011] (b) a second compartment comprising a core of ethylene-vinylacetate copolymer loaded with a steroid hormone and a non-medicated outer layer of ethylene-vinylacetate copolymer; and

[0012] (c) optionally placebo segments of a thermo-plastic material separating the first from the second compartment, fulfils these requirements.

[0013] The ring-shaped device according to the invention, is preferably a vaginal ring which can be used for hormone replacement therapy (HRT) or contraception.

[0014] The ethylene-vinyl acetate copolymer can be any commercially available ethylene-vinyl acetate copolymer, for instance as available under the trade names ELVAX®, EVATANE®, LUPOLEN V®, MOVRITON®, ULTRATHENE®, and VESTYPAR®.

[0015] The thermo-plastic material of the placebo segments can be any thermo-plastic material suitable for pharmaceutical use, such as polypropylene; low, linear low, or very low density polyethylene; ethylene-vinylacetate copolymer, and, preferably, high density polyethylene, such as commercially available ALATHON®, ALKATHENE®, BAYLON V®, CARLONA®, CARLONA P®, DOW PE®, ELTEX®, ELVAX®, EVATANE®, FERLENE®, FORTILENE®, HI-FAX®, HOSTAFLEX®, HOSTALEN G®, HOSTALEN PP®, LACTENE®, LUPOLEN®, LUPOLEN V®, LYTON®, MOPLEN®, MOVRITON®, NOVATEC®, NOVOLEN®, PRO-FAX®, PROPATHENE®, RIGIDEX®, STAMYLAN®, STAMYLAN P®, STAMYLEX®, TEAMEX®, TENITE®, TROLEN PP®, TYPAR®, ULTRATHENE®, VESTOLENP®, VESTYPAR®, and VESTOLEN A®.

[0016] Particularly good release patterns are obtained when the ethylene-vinyl acetate copolymer middle layer of the first compartment is saturated with the progestogen and the ethylene-vinyl acetate copolymer core of the second compartment is loaded with a just saturated, and most preferably with a sub-saturated mixture of the progestogen and the estrogen.

[0017] Preferred devices for contraceptive use have a first compartment wherein the steroid hormone is a progestogen and a second compartment wherein the steroid hormone is a mixture of a progestogen and an estrogen. Devices especially intended for hormone replacement therapy (“HRT”) may advantageously have a first compartment loaded with a mixture of a progestogen and an estrogen and a second compartment loaded with a progestogen. The progestogens of the first and the second compartment may be the same or may be different.

[0018] Typically the ethylene-vinyl acetate copolymer middle layer of the first compartment comprises the progestogen (or the mixture of the progestogen and the estrogen) in crystalline form.

[0019] The lengths of the compartments of the ring-shaped device are chosen to give the required performance. Ratios of the lengths of the first and second compartment are contemplated to be between 30:1 and 1:30, but usually are between 15:1 and 1:1, and preferably are about 2:1. The lengths of the placebo segments are long enough to prevent excessive mixing of the progestogen of the first compartment with the progestogen and/or estrogen of the second compartment. This is usually attained by applying placebo segments of a length between 0.5 and 70 mm. The necessary length depends on the nature of the thermo-plastic material and its capacity to prevent permeation of the active materials. Most ideally, the placebo segment completely prevents mixing, since mixing disturbs the release pattern. In practice, however, some mixing, in particular after a longer period of time, occurs due to diffusion of the active ingredients through the placebo segment from one to the other compartment. Such mixing would ultimately lead to the same load of estrogen in both compartments, which of course is unwanted when the loads are meant to be different. Some minor mixing, however, is not completely to be prevented and is allowed to the point that the mixing influences the release of the active ingredients in such a manner that plasma levels of active ingredients get outside the required values. In practice, less than 10% mixing, and preferably less than 5% mixing one month after insertion of the device, is acceptable. Usually a length of the placebo segments being preferably about at least half of the length of the second compartment is sufficient to prevent excessive mixing.

[0020] The ring-shaped device can be manufactured in any size as required. In practice, however an outer ring diameter of about 53.5 mm, a cross sectional diameter of about 3.5 mm, a length of the first compartment of about 100 to 110 mm, a length of the second compartment of about 10 to 40 mm, and a length of each of the two placebo segments of about 5 to 20 mm, has been proven to be very suitable for all purposes. If no placebo segments are used the length of the first compartment is about 110 and the length of the second compartment is preferably 42-52 mm.

[0021] The progestogen can be any suitable progestogen, such as desogestrel, etonogestrel (3-ketodesogestrel), levo-norgestrel, norgestrel, gestodene, and other compounds with similar progestogenic activity. Preferably the progestogen is etonogestrel. The estrogen can be any suitable estrogen, such as estradiol, estriol, mestranol, and ethinyl estradiol. For contraceptive use ethinyl estradiol is preferred, whereas for HRT estradiol is the preferred estrogen.

[0022] Using the most preferred ring-shaped device of the invention, the ethylene-vinylacetate copolymer layer of the first compartment is loaded with 5-60% w/w, and preferably with about 15% w/w of etonogestrel, and the ethylene-vinylacetate copolymer core of the second compartment is loaded with 0.05-3% w/w, and preferably about 0.25-0.5% w/w of etonogestrel and 0.05-5% w/w, and preferably about 0.75-1.5% w/w of ethinyl estradiol.

[0023] The preferred vaginal ring releases at least 90 &mgr;g/day of etonogestrel and 10 &mgr;g/day of ethinyl estradiol, with an upper limit of 450 &mgr;g/day and 100 &mgr;g/day respectively during Day 1-3, and 150 &mgr;g/day and 20 &mgr;g/day respectively during Day 4-21.

[0024] The ring-shaped devices can be prepared in any suitable manner for the manufacture of vaginal rings. A preferred method of manufacture of the ring-shaped device comprises co-extrusion of the core and the layer(s), medicated or non-medicated as required, of each of the first and second compartments to render a fiber with a medicated middle or core layer, respectively. These fibers are cut into pieces of the required lengths, and the pieces are assembled to the ring-shaped device in a mold kept at about 40° C., by injection molding with high density polyethylene of about 230° C. The rings are thereafter packed in the usual manner.

[0025] Another method of manufacture is a welding technique, for instance the hot-gas welding technique, which is especially suitable when no placebo segments are used. This technique is well known in the art. Basically the hot-gas technique is performed in an apparatus consisting of two molds which are used to clamp the fiber ends and hold them in line to each other. One mold is static and the other is movable. A movable stop is used to assure that the fiber ends are only sticking out of the mold by about 0.5 mm. The apparatus further comprises a capillary which is used to remove residual polymer. The capillary consists of two identical halves, one of which is mounted on the upper part of a mold and the other is mounted on the lower part of the mold. A hot-air gun may be used to melt the fiber ends.

[0026] In another embodiment, the two ethylene-vinylacetate copolymer fibers, loaded with either etonogestrel or a mixture of etonogestrel and ethinyl estradiol, are melt co-extruded together with the skin-core ethylene-vinylacetate copolymer to render a skin-core fiber. These skin-core fibers are cut into pieces of the required length and assembled to a ring in a mold with two suitable pieces injection molded high density polyethylene and injection molded at 230° C., with a mold temperature of 40° C. The rings are thereafter sterilized and packed in the usual manner, for instance packed in a sachet consisting of a PET (12 &mgr;m)/aluminum (9 &mgr;m)/LDPE (40 &mgr;m) laminate.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0027] FIG. 1 shows schematically an embodiment of a vaginal ring according to this invention, containing the first compartment (a), the second compartment (b) and two placebo segments (c).

[0028] FIG. 2 shows a cross-section along the line A-B of the first compartment.

[0029] FIG. 3 shows a cross-section along the line C-D of the second compartment.

[0030] FIG. 4 shows a cross-section along the line E-F of a placebo segment.

DETAILED DESCRIPTION OF THE INVENTION

[0031] In these drawings an embodiment of the invention is disclosed. The device is made of three compartments (a), (b), and (c), the first two of which comprise an ethylene-vinylacetate copolymer core (1) and (4) respectively, and the latter is a thermo-plastic placebo segment. In the first compartment (FIG. 2) the core (1) is non-medicated, and it further comprises an ethylene-vinylacetate copolymer middle layer (2) loaded with active ingredient, and an ethylene-vinylacetate copolymer outer layer (3) which is non-medicated. In FIG. 3 the core (4) is loaded with active ingredient, which core is surrounded by an ethylene-vinylacetate copolymer outer layer (5) which is non-medicated. The placebo segments (FIG. 4) preferably consist of one layer of non-medicated thermo-plastic material (6).

[0032] The invention is further illustrated by the following examples.

EXAMPLES

Example 1

[0033] A vaginal ring is composed from two steroid loaded compartments and two placebo segments, having the following composition and dimensions (see Figures):

[0034] First Compartment (FIG. 2)

[0035] a three-layered fiber comprising:

[0036] core (1): EVATANE® 1040 VN4; diameter 2.96 mm;

[0037] middle layer (2) loaded with 15% w/w of etonogestrel in EVATANE® 28-25; thickness 75 &mgr;m, extruded at 105° C.;

[0038] outer layer (3): EVATANE® 1040 VN4; thickness 195 &mgr;m.

[0039] The steroid loaded mixture and EVATANE® 1040 VN4 are co-extruded at 120° C. to form a trilayer fiber.

[0040] Second Compartment (FIG. 3)

[0041] a two-layered fiber comprising:

[0042] core (4): EVATANE® 28-25 loaded with 0.5% w/w of etonogestrel and 1.5% w/w of ethinyl estradiol (EE); diameter 3.35 mm, extruded at 105° C.;

[0043] outer layer (5): EVATANE® 1020 VN3; thickness 75 &mgr;m.

[0044] The steroid loaded mixture and EVATANE® 1020 VN3 are co-extruded at 110° C. to form a skin-core fiber.

[0045] Placebo Segments (FIG. 4)

[0046] two placebo segments of 16 mm length each, comprising STAMYLEX® 9119 (6); diameter 3.5 mm.

[0047] The tri-layer fiber is cut into fiber pieces of 110 mm and the skin-core fiber is cut into fiber pieces of 15 mm. One small and one large fiber piece are joined together to a ring-shaped device by injection molding of the two placebo segments (HDPE) at 230° C., with a mold temperature of 40° C.

Example 2

[0048] According to the procedure of Example 1, ring-shaped devices were prepared comprising compartments having the following content:

[0049] First Compartment

[0050] skin/core: EVATANE® 1040 TN4;

[0051] middle layer: EVATANE® 28-25 loaded with etonogestrel;

[0052] outer diameter 3.5 mm. 1 Medicated skin medicated extrusion layer load thickness layer thickness temp. (% w/w) (&mgr;m) (&mgr;m) (° C.) 10 230 75 120 15 195 75 120 15 230 75 120 15 265 75 120 15 230 75 145 15 175 75 120 15 195 65 120 15 195 85 120

[0053] Second Compartment

[0054] core: EVATANE® 28-25 loaded with etonogestrel and ethinyl estradiol (EE); outer layer: EVATANE® 1020 VN3 or EVATANE® 1040 VN4; outer diameter 3.5 mm. 2 medicated layer medicated layer skin extrusion load etonogestrel load EE thickness temp. (% w/w) (% w/w) (&mgr;m) (° C.) skin material: EVATANE ® 1020 VN3 0.5 1.5 65 105 0.5 1.5 80 105 0.8 1.5 50 105 0.8 1.5 65 105 0.8 1.5 80 105 0.5 1.5 75 105 0.5 1.5 75 103 0.5 1.5 75 115 0.45 1.5 75 110 0.5 1.5 75 110 0.55 1.5 75 110 0.5 1.35 75 110 0.5 1.65 75 110 0.25 0.75 85 110 skin material: EVATANE ® 1040 VN4 0.37 1.1 345 120 0.37 1.1 380 110 0.37 1.1 425 110

[0055] Placebo Segments

[0056] two placebo segments of 16 mm length each, comprising STAMYLEX® 9119.

Example 3

[0057] The following first compartments containing etonogestrel were prepared. Medicated layer material is EVATANE® 28-25; outer diameter is 3.5 mm. 3 medicated Medicated layer load skin layer extrusion skin/core etonogestrel thickness thickness temp. Entry EVATANE ® % w/w &mgr;m &mgr;m ° C. 1 1040 VN4 10 230 75 120 2 1040 VN4 15 195 75 120 3 1040 VN4 15 230 75 120 4 1040 VN4 15 265 75 120 5 1040 VN4 15 230 75 145 6 1040 VN4 15 195 65 120 7 1040 VN4 15 195 85 120

[0058] The following second compartments containing etonogestrel and ethinyl (EE) were prepared. Medicated layer material is EVATANE® 28-25; outer diameter is 3.5 mm. 4 medicated layer load etono- skin extrusion skin Gestre EE thickness temp. Entry EVATANE ® % w/w % w/w &mgr;m ° C. 8 1020 VN3 0.5 1.5 65 105 9 1020 VN3 0.5 1.5 80 105 10 1020 VN3 0.8 1.5 50 105 11 1020 VN3 0.8 1.5 65 105 12 1020 VN3 0.8 1.5 80 105 13 1020 VN3 0.5 1.5 75 105 14 1020 VN3 0.5 1.5 75 103 15 1020 VN3 0.5 1.5 75 115 16 1020 VN3 0.45 1.5 65 110 17 1020 VN3 0.5 1.5 75 110 18 1020 VN3 0.55 1.5 75 110 19 1020 VN3 0.5 1.35 75 110 20 1020 VN3 0.5 1.65 75 110 21 1020 VN3 0.25 0.75 75 120 22 1020 VN4 0.37 1.1 345 120 23 1020 VN4 0.37 1.1 380 110 24 1020 VN4 0.37 1.1 425 110

[0059] The following vaginal rings were prepared according to the method of Example 1:

[0060] (a) first compartment of material of entry 6 (110 mm);

[0061] second compartment of material of entry 9 (15 mm);

[0062] placebo segments of STAMYLEX® 9119 (16 mm).

[0063] (b) first compartment of material of entry 7 (1 10 mm);

[0064] second compartment of material of entry 13 (16 mm);

[0065] placebo segments of STAMYLEX® 9119 (16mm).

[0066] (c) first compartment of material of entry 7 (110 mm);

[0067] second compartment of material of entry 13 (15 mm);

[0068] placebo segments of STAMYLEX® 9119 (16 mm).

[0069] (d) first compartment of material of entry 6 (110 mm);

[0070] second compartment of material of entry 21(20 mm);

[0071] placebo segments of STAMYLEX® 9119 (15.5 mm).

[0072] (e) first compartment of material of entry 6 (110 mm);

[0073] second compartment of material of entry 21(30 mm);

[0074] placebo segments of STAMYLEX® 9119 (8.5 mm).

[0075] (f) first compartment of material of entry 7 (110 mm);

[0076] second compartment of material of entry 13 (17 mm);

[0077] placebo segments of STAMYLEX® 9119 (13 mm).

[0078] (g) first compartment of material of entry 6 (1 10 mm);

[0079] second compartment of material of entry 22 (20 mm);

[0080] placebo segments of STAMYLEX® 9119 (13.5 mm).

[0081] (h) first compartment of material of entry 7 (1 10 mm);

[0082] second compartment of material of entry 22 (21 mm);

[0083] placebo segments of STAMYLEX® 9119 (13 mm).

[0084] (i) first compartment of material of entry 6 (110 mm);

[0085] second compartment of material of entry 22 (24 mm);

[0086] placebo segments of STAMYLEX® 9119 (8.5 mm).

[0087] (j) first compartment of material of entry 6 (110 mm);

[0088] second compartment of material of entry 23 (21 mm);

[0089] placebo segment of STAMYLEX® (9119 (12 mm).

[0090] (k) first compartment of material of entry 6 (110 mm);

[0091] second compartment of material of entry 24 (21 mm);

[0092] placebo segment of STAMYLEX® 9119 (12 mm).

Example 4

[0093] A vaginal ring is composed from two steroid loaded compartments having the following composition and dimensions (see FIGS. ):

[0094] First Compartment (FIG. 2)

[0095] a three-layered fiber comprising:

[0096] core (1) EVATANE® 1040 VN4; diameter 2.96 mm; middle layer (2) loaded with 15% w/w of etonogestrel in EVATANE® 28-25; thickness 75 &mgr;m, extruded at 105° C.; outer layer (3): EVATANE® 1040 VN4; thickness 195 &mgr;m.

[0097] The steroid loaded mixture and EVATANE® 1040 VN4 are co-extruded at 120° C. to form a trilayer fiber.

[0098] Second Compartment (FIG. 3)

[0099] a two-layered fiber comprising:

[0100] core (4): EVATANE® 28-25 loaded with 0.25% w/w of etonogestrel and 0.75% w/w of ethinyl estradiol (EE); diameter 3.35 mm, extruded at 105° C., outer layer (5): EVATANE® 1020 VN3 thickness 145 &mgr;m.

[0101] The steroid loaded mixture and EVATANE® 1020 VN3 are co-extruded at 110° C. to form a skin-core fiber.

[0102] The trilayer fiber is cut into fiber pieces of 110 mm and the skin-core fiber is cut into fiber pieces of 47 mm. One small and one large fiber piece are joined together to a ring-shaped device by hot-gas welding technique.

Example 5

[0103] The following first compartments containing etonogestrel were prepared. The medicated layer material is EVATANE 28-25; the skin/core material is EVATANE 1040 VN4 (outer diameter is 3.5 mm). 5 Medicated layer Skin Medicated layer Extrusion load thickness thickness temp. Entry (% w/w) (&mgr;m) (&mgr;m) (° C.) 25 15 175 75 120 26 15 140 75 120 27 15 220 75 120

[0104] The following second compartments containing etonogestrel and ethinyl estradiol (EE) were prepared. The medicated layer material is EVATANE 28-25; the skin material is EVATANE 1020 VN3 (outer diameter is 3.5 mm). 6 medicated layer load Etonogestrel EE skin thickness extrusion temp. Entry (% w/w) (% w/w) (&mgr;m) (° C.) 28 0.25 0.75 85 110 29 0.25 0.75 125 110 30 0.25 0.75 145 110 31 0.30 0.90 175 110 32 0.20 0.60 115 110 33 0.15 0.45 145 110

[0105] The following vaginal rings were prepared according to the method of Example 4:

[0106] a) First compartment of material of entry 2 (110 mm)

[0107] second compartment of material of entry 31(47 mm)

[0108] b) First compartment of material of entry 2 (110 mm)

[0109] second compartment of material of entry 32 (47 mm)

[0110] c) First compartment of material of entry 25 (100 mm)

[0111] second compartment of material of entry 30 (50 mm)

[0112] d) First compartment of material of entry 6 (110 mm)

[0113] second compartment of material of entry 30 (47 mm)

[0114] e) First compartment of material of entry 7 (110 mm)

[0115] second compartment of material of entry 29 (40 mm)

[0116] f) First compartment of material of entry 26 (80 mm)

[0117] second compartment of material of entry 33 (75 mm)

[0118] g) First compartment of material of entry 27 (125 mm)

[0119] second compartment of material of entry 28 (30 mm)

Claims

1. A ring-shaped device, comprising:

a first compartment comprising a non-medicated core of ethylene-vinylacetate copolymer, encircled by a crystalline, steroid hormone saturated ethylene-vinylacetate copolymer middle layer, and a non-medicated outer layer of ethylene-vinylacetate copolymer; and

a second compartment comprising a core of ethylene-vinylacetate copolymer loaded with a steroid hormone and a non-medicated outer layer of ethylene-vinylacetate copolymer;

wherein an initial release of the crystalline, steroid hormone from the first compartment and the steroid hormone from the second compartment lacks a burst effect.

2. The ring-shaped device of clam 1, wherein the crystalline, steroid hormone of the middle layer of the first compartment is a progestogen, and the steroid hormone of the ethylene-vinylacetate copolymer core of the second compartment is a mixture of a progestogen and an estrogen.

3. The ring-shaped device of claim 2, wherein the ethylene-vinylacetate copolymer core of the second compartment is loaded with a sub-saturated mixture of the progestogen and the estrogen.

4. The ring-shaped device of claim 1, wherein the first and second compartment lengths have a ratio of between 15:1 and 1:1.

5. The ring-shaped device of claim 1, further comprising at least one placebo segment of a thermoplastic material separating said first compartment from said second compartment.

6. The ring-shaped device of claim 5, wherein a diameter of the ring-shaped device is about 53.5 mm, a cross-sectional diameter of the ring-shaped device is about 3.5 mm, a length of the first compartment is about 100 to 110 mm, a length of the second compartment is about 10 to 40 mm, and a length of the at least one placebo segment is about 5 to 20 mm.

7. The ring-shaped device of claim 5, wherein said thermoplastic material is high density polyethylene.

8. The ring-shaped device of claim 5, wherein a length of the at least one placebo segment is sufficient to prevent substantial mixing of the crystalline, steroid hormone of the first compartment with the steroid hormone of the second compartment.

9. The ring-shaped device of claim 8, wherein the at least one placebo segment is approximately at least half of the length of the second compartment.

10. The ring-shaped device of claim 2, wherein the progestogen is etonogestrel and the estrogen is ethinyl estradiol.

11. The ring-shaped device of claim 10, wherein the middle ethylene-vinylacetate copolymer layer of the first compartment is loaded with about 15% w/w of etonogestrel, and the ethylene-vinylacetate copolymer core of the second compartment is loaded with about 0.25 to 0.5% w/w of etonogestrel and about 0.75 to 1.5% w/w of ethinyl estradiol.

12. The ring-shaped device of claim 4, wherein the ratio is about 2:1.

13. The ring-shaped device of claim 1, wherein the ring diameter is about 53.5 mm, the cross-sectional diameter is about 3.5 mm, the length of the first compartment is about 100 to 110 mm, and the length of the second compartment is about 42 to 52 mm.

14. The ring-shaped device of claim 11, wherein, at least, 90 &mgr;g/day of etonogestrel and 10 &mgr;g/day of ethinyl estradiol release from the ring-shaped device.

15. The ring-shaped device of claim 14, wherein, at most, 450 &mgr;g/day of etonogestrel and 100 &mgr;g/day of ethinyl estradiol release from the ring-shaped device during days 1-3.

16. The ring-shaped device of claim 15, wherein, at most, 150 &mgr;g/day of etonogestrel and 20 &mgr;g/day of ethinyl estradiol release from the ring-shaped device during days 4-21.

17. A method for manufacturing a ring-shaped device, said method comprising:

co-extruding a non-medicated core, a middle layer, and a non-medicated outer layer of ethylene-vinylacetate copolymer into a first fiber;

co-extruding a core and a non-medicated outer layer of ethylene-vinylacetate copolymer into a second fiber; and

melting the first fiber and the second fiber to at least one placebo segment in a mold to form the ring-shaped device.

18. The method according to claim 17, further comprising welding the first compartment to the second compartment.

19. The method according to claim 17, further comprising saturating the middle layer of the first compartment with crystalline, steroid hormone during the co-extrusion.

20. The method according to claim 17, wherein said at least one placebo segment is thermoplastic material.