The present invention relates to a method for the prevention of graft rejection, and to the preparation of a pharmaceutical preparation for the treatment of patients having undergone transplantation of various organs and tissue.

The preferred drug for prevention of graft rejection in the clinic is cyclosporin A, but the use of this com- pound is limited by its adverse effect, e.g. nephro- toxicity.

It is known that lα,25-dihydroxyvitamin D„ (in the following also referred to as lα,25-(OH)_D ₃ ) alone or in combination with immunosuppresive agents prolongs skin graft survival in mice (Jordan, S.C., Shibuka, R., Mullen, Y. : Abstract Seventh workshop of vitamin D, Rancho Mirage, California, April 24-29 (1988), p. 67). However, the dose of lα,25-(OH) ₂ D ₃ which can be administered is limited by a high mortality rate in mice given more than the minimal active dose thus limiting the potential use of this com¬ pound in treatment of diseases characterized by graft versus host or host versus graft rejection, especially in the prevention of graft rejection in humans.

It has now surprisingly been found that a number of vitamin D metabolites and analogues thereof which have only moderate activity on the calcium metabolism when compared to lα,25-dihydroxyvitamin D«, but having retained the abil¬ ity, to activate receptors for lα,25-dihydroxyvitamin D_ not associated with calcium absorption, show a similar or even better effect in the prevention of graft versus host'or host versus graft rejection.

Such compounds can be given in a higher and more ef¬ fective dose than lα,25-(OH)-D ₃ without side effects caused by hypercalcemia. Furthermore, these compounds are well tolerated and do not give rise to adverse effects, such as the nephro-

toxicity caused by cyclosporin A.

Examples of vitamin D metabolites and analogues for use in the present pharmaceutical preparations are

1) compounds described in international patent appli¬ cation No. PCT/DK86/00081, international filing date 14th July, 1986, International Publication No. WO 87/00834, in particular the compound designated MC 903 (example 5 in said patent application) (confer also Calverley, ., Tetra- he ron 43, 4609-4619 (1987); Binderup, L. and Bramm, E., Biochemical Pharmacology 37, 889-895 (1988)),

2) 24-homo- and 26-homo-lα,25-dihydroxyvitamin D_

(together with their 22,23-didehydro-analogues) (Ostrem, V.K. et al, Proc. Natl. Acad. Sci. USA 8_4, 2610-2614 (1987)),

3) 20-oxa-21-nor-lα,25-dihydroxyvitamin D ₃ and 22- oxa-lα,25-dihydroxyvitamin D_ (Abe, J. et al, FEBS Letters 226, 58-62 (1987)), and

4) 26,27-dimethyl- and 26,27-diethγl-lα,25-dihydroxγ- vitamin D ₃ , and 24,24-difluoro-24-homo-lα,25-dihγdroxy- vitamin D ₃ (Ikekawa, N. et al, Chem. Pharm. Bull. 35, 4362-65 (1987)),

these examples only being indicative of, and not limiting, for the choice of vitamin D metabolites or analogues.

The treatment may be performed with the vitamin D compound or analogue alone or in combination with an immunosuppresive agent such as cyclosporin A, a steroid such as prednisone, azathioprine, cyclophosphamide or anti- lymphocyte serum.

The present compounds are intended for use in pharma¬ ceutical preparations which are useful in the treatment of human disorders as described above.

The amount required of the active compound for thera- peutic effect will, of course, vary both with the partic¬ ular compound and the route of administration. The com¬ pounds of the invention can, as mentioned above, be admini¬ stered by the parenteral, enteral or topical route. When

the active compound is well absorbed when given enterally, this is the preferred form of administration in the sys¬ temic treatment of the said disorder.

While it is possible for an active compound to be administered alone as the raw chemical, it is preferable to present it as a pharmaceutical preparation. Conveniently, the active compound comprises from 0.1 μg/g to 1 mg/g of the preparation.

By the term "dosage unit" is meant a unitary, i.e. a single dose which is capable of being administered to a patient, and which may be readily handled and packed, re¬ maining as a physically and chemically stable unit dose comprising either the active material as such or a mixture of it with solid or liquid pharmaceutical diluents or car- riers.

The preparations of the present invention comprise an active compound in association with a pharmaceutically ac¬ ceptable carrier therefore and optionally other therapeutic ingredient(s). The carrier(s) must be "acceptable" in the sense of being compatible with the other ingredients of the preparations and not deleterious to the recipient thereof. The preparations include e.g. those in a form suit¬ able for oral, rectal, parenteral (including subcutaneous, and intravenous), and topical administration. The preparations may conveniently be presented in dosage unit form and may be prepared by any of the methods well known in the art of pharmacy. All methods include the step of bringing the active compound into association with the carrier which constitutes one or more accessory ingre- dients. In general, the preparations are prepared by uni¬ formly and intimately bringing the active compound into association with a liquid carrier or a finely divided, solid carrier or both, and then, if necessary, shaping the prod¬ uct into the desired preparation. Preparations of the present invention suitable for oral administration may be in the form of discrete units as capsules, sachets, tablets or lozenges, each containing a predetermined amount of the active compound; in the form of

a powder or granules; in the form of a solution or a sus¬ pension in an aqueous liquid or non-aqueous liquid; or in the form of an oil-in-water emulsion or a water-in-oil emulsion. The active compound may also be administered in the form of a bolus, electuary or paste.

A tablet may be made by compressing or moulding the active compound optionally with one or more accessory ingredients. Compressed tablets may be prepared by comp¬ ressing, in a suitable machine, the active compound in a free-flowing form such as a powder or granules, optionally mixed by a binder, lubricant, inert diluent, surface active or dispersing agent. Moulded tablets may be made by mould¬ ing, in a suitable machine, a mixture of the powdered active compound and suitable carrier moistened with an inert liquid diluent.

Preparations for rectal administration may be in the form of a suppository incorporating the active compound and a carrier such as cocoa butter, or in the form of an enema. Preparations suitable for parenteral administration conveniently comprise a sterile oily or aqueous preparation of the active compound which is preferably isotonic with the blood of the recipient.

Preparations suitable for topical administration in- elude liquid or semi-liquid preparations, such as liniments, lotions, applicants, oil-in-water or water-in-oil emulsions such as creams, ointments or pastes; or solutions or sus¬ pensions such as drops.

In addition to the aforementioned ingredients, the preparations of this invention may include one or more additional ingredients such as diluents, buffers, flavour¬ ing agents, binders, surface active agents, thickeners, lubricants, preservatives, e.g. methyl hydroxybenzoate (including anti-oxidants), emulsifying agents and the like.

The preparations may further contain other therapeu- tically active compounds usually applied in the above mentioned treatment.

In the topical treatment, ointments, creams, or lo¬ tions containing from 1-500 μg/g of the vitamin D analogues or metabolites are administered. The oral preparations are formulated, preferably as tablets, capsules, or drops, con- taining from 0.5-1000 μg of the vitamin D analogues or metabolites, per dosage unit.

The present invention further concerns a method for treating patients in risk of experiencing graft rejection, said method consisting of administering to a patient in need of treatment an effective amount of one or more of the above mentioned vitamin D analogues or metabolites, alone or in combination with one or more other therapeutically active compounds usually applied in such treatment. The treatment with the present compounds and/or with further therapeutically active compounds may be simultaneous or with intervals.

In the systemic treatment, daily doses of from 1-5000 μg, preferably from 2-1000 μg, of the vitamin D analogues or metabolites are administered. The invention will now be further described in the following non-limiting Examples:

Example 1 Dermatological Cream Containing

MC-903 In 1 g almond oil was dissolved 1 mg MC 903. To this solution was added 40 g of mineral oil and 20 g of self- -emulsifying beeswax. The mixture was heated to liquify. After the addition of 40 ml hot water, the mixture was mixed well. The resulting cream contains approximately 10 μg of MC 903 per gram of cream.

Example 2 Capsules containing 22-oxa-lα,25-dihv- droxyvitamin D ₃ 22-oxa-lα,25-dihydroxyvitamin D ₃ was suspended in arachis oil to a final concentration of 50 μg 22-oxa-lα,25- -dihydroxyvitamin D ₃ /ml oil. 10 Parts by weight of gela¬ tine, 5 parts by weight glycerine, 0.08 parts by weight potassium sorbate, and 14 parts by weight distilled water

were mixed together with heating and formed into soft gela¬ tine capsules. These were then filled each with 100 μl of the 22-oxa-lα,25-dihydroxyvitamin D _g in oil suspension, such that each capsule contained 5 μg 22-oxa-lα,25-di- hydroxyvitamin D ₃ .