Heterogeneous implantable devices for drug delivery

1. An implantable device for delivery of a pharmaceutical substance to a patient, comprising:

a rod-shaped core comprising a core polymeric material wherein the core does not comprise a pharmaceutical substance, wherein the core polymeric material is ethylene vinyl acetate (EVA), and wherein the core has a diameter of about 0.5 mm to about 3.5 mm;

a first layer comprising a first-layer pharmaceutical substance and EVA surrounding the core; and

one or more additional layers, wherein each of the one or more additional layers comprise an independently selected additional pharmaceutical substance and EVA in a blend,

wherein the EVA has a flexural strength when unblended with pharmaceutical substance,

wherein the blend of the additional pharmaceutical substance and the EVA in each of the one or more additional layers has about 20% to 90% of the flexural strength of the EVA unblended with pharmaceutical substance;

wherein the first-layer pharmaceutical substance and the additional pharmaceutical substances are the same or different;

wherein the first-layer pharmaceutical substance and the additional pharmaceutical substances are released through pores that open to the surface of the device; and

wherein the outermost layer of the device comprises at least one of the additional pharmaceutical substances.

2. The device of claim 1 , wherein the first layer and the one or more additional layers comprise a pharmaceutical substance independently selected from the group consisting of: anastrozole, apomorphine, beraprost, buprenorphine, buserelin, dutasteride, finasteride, haloperidol, iloprost, L-thyroxine, L-triiodothryonine, leuprolide, lisuride, nalmefene, nicotine, pramipexole, rasagiline, risperidone, ropinerole, rotigotine, selegiline, sirolimus, tacrolimus, tamsulosin, and testosterone.

3. The device of claim 1 , wherein the first-layer pharmaceutical substance is buprenorphine.

4. The device of claim 1 , wherein the first layer and the one or more additional layers comprise a pharmaceutical substance independently selected from the group consisting of 5-alpha-reductase inhibitors, analeptic agents, analgesics, angiotensin converting enzyme, anticancer agents, anticancer preparations, anticholinergic drug inhibitors, anticoagulants, anticonvulsants, antidepressants, antidiabetic agents, antienuresis agents, anti-inflammatory agents, anti-obesity preparations, antiparasitics, anti-parkinsonism drugs, anti-platelet agents, anti-psychotics, antispasmodics and anticholinergics, anti-thrombotics, antiviral agents, bronchial dilators, calcium channel blockers, central nervous system stimulants, cholesterol reducers and anti-hyperlipemics, diuretics, dopamine agonists, histamine H receptor antagonists, hormones, steroid hormones, peptide hormones, thyroid hormones, hormone mimetics, mimetics of steroid hormones, mimetics of peptide hormones, mimetics of thyroid hormones, hyperglycemic agents, immunosuppressives, narcotic antagonists, narcotic detoxification agents, ophthalmological osmotic dehydrating agents, respiratory stimulants, restenosis-inhibiting agents, sympatholytics, thyroid preparations, and uricosuric agents.

5. The device of claim 1 , wherein the first-layer pharmaceutical substance, and one or more additional pharmaceutical substances are independently selected from the group consisting of hormones, growth factors, angiopeptin, angiotensin converting enzyme inhibitors, captopril, cilazapril, and lisinopril.

6. The device of claim 1 , wherein the first-layer pharmaceutical substance, and one or more additional pharmaceutical substances are independently selected from the group consisting of calcium channel blockers, nifedipine, and triazolopyrimidine.

7. The device of claim 4 , wherein the anticancer agent is selected from the group consisting of androgens.

8. The device of claim 4 , wherein the anti-thrombotic agent is selected from the group consisting of beraprost, clopidogrel, and iloprost.

9. The device of claim 1 , wherein the first-layer pharmaceutical substance, and one or more additional pharmaceutical substances are independently selected from the group consisting of buprenorphine and fentanyl.

10. The device of claim 1 , wherein each of the first layer and the one or more additional layers has a different average concentration of pharmaceutical substance.

11. The device of claim 10 , wherein the average concentration of pharmaceutical substance in the one or more additional layers decreases with increasing distance from the core.

12. The device of claim 10 , wherein the average concentration of pharmaceutical substance in the one or more one or more additional layers increases with increasing distance from the core.

13. The device of claim 1 , wherein the first-layer pharmaceutical substance is buprenorphine.

14. The device of claim 13 , wherein the first layer comprised of EVA and buprenorphine comprises about 10% to 85% buprenorphine.

15. A method for delivering a first-layer pharmaceutical substance, and one or more additional pharmaceutical substances to a patient in need thereof, comprising the step of inserting a device of claim 1 subcutaneously into the patient.

16. The method of claim 15 , wherein the device remains implanted in the patient for about 3 months to about 24 months.

17. The method of claim 16 , wherein the concentration of pharmaceutical substance in the blood is approximately constant or essentially constant for about 3 months to about 24 months.