SE433038B - PROCEDURE FOR CLEANING LIPOSOM SUSPENSIONS FROM NON-CONTAINED MEDICINAL PRODUCTS - Google Patents

Description

7810109-4 molecular filter Sepharose GB.

The liposomes are first eluted while the free drug is retained by the sepharose.

Another suitable method is ultracentrifugation at 100,000 g and subsequent washing, always with ultracentrifugation, with buffered solution. It has been shown that the liposomes in animals can transport antitumor active drug selectively to neoplastic cells.

The present invention relates to a novel process for the separation of liposomes from non-entrapped drug.

Ion exchange resins and adsorbent resins were used without the need for chromatography. The ion exchange resin is added to the liposome suspension of the drug which must be purified and the whole is shaken for 1 to 120 minutes.

The free liposome suspension is obtained after filtration through a porous layer, which holds back the resin on which the free drug is absorbed. This new purification process in which ion exchange resins are used has the great advantage that highly concentrated liposome suspensions (up to 4 mg / ml adriamycin hydrochloride) can be obtained which cannot be obtained by chromatography with a molecular filter (maximum 200 .mu.m ml. The highly stable liposome suspension thus obtained In contrast to the suspensions obtained by high speed centrifugation, there is no tendency for sedimentation.The definitive chemical stabilization is achieved by freeze-drying the liposome suspension.

The invention is further illustrated by the following examples.

Example 1: In a saponification flask, 1.5 g of egg lecithin, 0.4 g of cholesterol and 0.2 g of dicetyl phosphate in chloroform and the solvent were dissolved. ....____ a _..._.__.._. ___ ,, _ 781.01 09-13 was evaporated to dryness. An adriamycin hydrochloride solution (concentration 20 mg / ml) in 0.007 N buffer phosphate was then added and the solution was shaken for 1 minute with ultrasound.

The suspension was then allowed to stand for 30 minutes at room temperature and under a nitrogen atmosphere, after which 2 g of BDH IR-50 resin, previously activated in the sodium form, were added (the weight refers to the dry weight and corresponds to 5 ml of expanded resin). The contents of the flask were shaken for 30 minutes.

Then the suspension was filtered through a porous layer (G 1). Liposomes with a varying size of from 0.5 to 2 microns of oil with a content of 60% of the starting amount of adriamycin were obtained. They were made stable by freeze-drying.

Example 2.

The same procedure as in Example 1 was used and the same amounts of adriamycin and lipids were used, the ultrasound shaking being extended to 10 minutes to obtain liposomes with a size smaller than 1 micron. A non-granular resin was chosen which also exhibits the function of a filter, since the total body of the liposomes exhibits a size which is not completely homogeneous. Accordingly, 10 ml of Dowex 5OW-4 (100-200 mesh) resin previously activated in the sodium form was introduced into the flask. After filtration, a suspension was obtained which contained liposomes with a size of 0.2-0.8 microns and 75% of the starting adriamycin. Thereafter, the liposomes were made stable by lyophilization.

Example 3.

A solution of 5-fluorouracil having a concentration of 10 mg / ml in 0.007 N buffer phosphate and having a pH of 8 was poured into the saponification flask containing the lipid phase, which was prepared as described above. The suspension was treated as in Example 1 using 10 ml of Amberlite RA-400 (Cl) previously activated as chlorohydrate as the filter resin. The liposomes thus obtained were made stable by lyophilization.

Exemgel 4.

Liposomes of 5-fluorouracil were prepared as described above using 1.5 g of egg lecithin, 0.4 g of cholesterol and 0.2 g of stearylamine. 10 ml of pre-activated Dowexšà resin (50-100 mesh) were used as the purification system. The liposomes thus obtained were stabilized by freeze-drying.

Example 5.

An adriamycin liposome suspension was prepared under the same conditions and using the same amounts as described in Example 2 and purified using 15 g of Rohm & Haas adsorbent XAD resin, which was introduced directly into the preparation flask.

After shaking for 40 minutes and filtering through sintered filter glass (3 l, a liposome suspension was obtained which contained about 50% of the initial amount of adriamycin; this suspension was stabilized by freeze-drying.

Claims (4)

7810109-4 PATENT REQUIREMENTS 1. A process for purifying liposome suspensions from non-entrapped drug is characterized in that ion exchange resins are used both in activated and non-activated form in salt form and, if desired, the liposome suspensions are lyophilized for stabilization. 2. A method according to claim 1, characterized in that absorbent polymeric substances are used. 3. A method according to claim 1, characterized in that strong or weak anion-type resins are used. 4. A method according to claim 1, characterized in that strong or weak cation-type resins are used. . .__ _ .., .__..._..._..__.__.... 7810109-4 SUMMARY. The present invention relates to a novel process for the preparation of injectable liposomes in which liposome suspensions are purified from non-entrapped drug using ion exchange resins in both activated and iclet-activated form in salt form.