FR2581543A1 - Pharmacological technique which makes it possible to produce an orally active insulin preparation. - Google Patents

Abstract

This galenic technique uses the formation of insulin-containing multivesicular liposomes, the latter are then freeze-dried to allow their use in capsules or in the form of tablets, the final stage is the carrying out of successive coatings with a gastroresistant substance. The active ingredient represented by insulin is successively protected from the action of digestive proteolytic enzymes by the gastroresistant coating, and then by the liposomal form itself. The production of multivesicular liposomes allows, in addition, an action which is spread out over time since not all the liposomal structures are destroyed immediately. Technical field represented by pharmacy.

Description

Insulin is a hypoglycaemic polypeptide hormone with a molecular weight of about 6000; it represents the specific treatment of hyperglycemia.

Secreted by the pancreas, insulin has two chains: a chain 4 of 21 amino acids (devoid of basic amino acids) and a chain B of 30 amino acids (containing basic amino acids); there are 3 disulfide bridges: 2 interchain bridges and an intrachain bridge.

In solution, take into account the insulin concentration, pH,
2+ of the ionic strength and the quantity of Zn ions, insulin exists in the form of monomers, dimers, tetramers or hexamers.

Purified it is an amorphous, colorless powder, quite alterable, soluble in acidified or alkaline water, in weak alcohol or glycerin, insoluble in ether, chloroform, absolute alcohol, entirely soluble in solutions of sodium phosphate, it nevertheless remains insoluble at its pHi = 5s5 5.5.

Dialyzable, precipitating by the main dealuminizing reagents, its properties are not altered by moderate heating to 70du.

It is more easily destroyed in an alkaline or acidic environment than in a neutral solution.

Spilled in the portal circulation, insulin first reaches the liver which inactivates about half of it: portal insulinemia is- much higher than that of peripheral blood, which seems necessary to stop the hepatic flow of glucose.

In plasma, insulin is linked in variable proportions to autXptou plasma tins in inactive form.

Insulin is destroyed by several organs, in particular the liver and the kidney: disulfide bridges are broken by insulinase, then hxdr-ol-f of peptide chains.

The problem with the use of exogenous insulin is due to the fact that "insulin is inactive by the oral route" because it is destroyed
by proteolytic digestion e-zymes; hence the necessity
parenteral goose, and the inability to actually mimic the
endocrine pancreas, because physiologically insulin first reaches
the liver having to be diluted in the peripheral circulation.

The present invention relates to a galenical technique ensuring a
increased protection of the active ingredient (represented by insulin) and
allows the pharmacological qualities to be preserved during administration
oral tration.

A lipid phase is carried out by dissolving phospholipids
amphiphiles and neutral lipids in a mixture of chloroform and
ether.

The aqueous phase is conducted by dissolving insulin in a so
aqueous maltose solution.

The aqueous and lipid phases are then poured one onto the other.
tre, while the container used for the preparation is gently
restless.

Once the aqueous phase has been completely added to the organ phase
the container is sealed, and the volume of air
trapped is driven off by a stream of nitrogen.

In order to achieve a water-in-oil emulsion, vigorous stirring
reuse of the previously formed mixture is necessary for about ten-minutes.

This emulsion is then placed in a container containing a
more concentrated maltose solution than that used previously.

Vigorous stirring for a few seconds allows obtaining
chloroform and ether spherules containing the insulin solution.

A gentle agitation, under a stream of nitrogen, is necessary for preve
to limit the sedimentation of the spherules.

 By moderate heating, the organic solvents are evaporated. This operation can be objectified by the decrease in the turbidity of the suspension.

Once the organic solvents have evaporated, the structure of the lipos
multivesicular somes is formed.

 In order to separate the non-vesicular substances and the lipid debris, a subsequent separation either by dialysis or by centri faction is necessary.

The multivesicular insulin liposomes are then lyophilized.

Freeze-drying should not be too fast, so as not to destroy the liposomal structures; nor too slow, so as not to distort the active principle by increasing the osmolarity.

The resulting lyophilisate is stored in a controlled hygroscopy atmosphere until it is distributed into capsules.

The capsules containing the lyophilisate are then made gastro-resistant by successive filming of a substance not attacked in the stomach.

This pharmacotechnical practice makes it possible to produce an active insulin preparation by the oral route.

1) The gastro-resistant coating makes it possible to subtract the multivesicular liposomes from insulin to gastric juice and more particularly to the destructive action of pepsin vis-à-vis insulin at this pH; the optimum pH for action of pepsin being very low, around 2. In the intestinal environment, where the pH is higher, pepsin will have practically no proteolytic action vis-à-vis insulin .

 2) Lyophilization of multivesicular insulin liposomes allows their shaping in capsules.

 It should be noted that dry granulation can also give rise to tablets.

3) The production of multivesicular insulin liposomes is carried out for multiple reasons, in particular: the liposomal form first of all makes it possible to mask the insulin from the proteolytic enzymes which destroy digestion (trypsin, chy motrpsir, enterol-are. ..; eistan to the existing intestinal level, therefore to prevent its denaturation the liposomes have been demonstrated to promote the penetration of polypeptides through the intestinal mucosa; moreover, they are relatively stable with respect to bile salts; the multivesicular liposomes by their structure allow a high envesiculation of the active principle, a release spread out in time of the active principle since all the phospholipidic structures are not destroyed in a single instant.

The implementation of multivesicular insulin liposomes can be carried out using 0.450 mole of phosphatidylethanolamine, 0.450 mole of cholesterol, 0.100 mole of phosphatidylserine, 0.100 mole of triolein in 100 liters of a mixture of chloroform and ether in equal proportion; 150 grams of insulin crystallized from 100 liters of an aqueous 0.15 M maltose solution; and 500 liters of a 0.20 M aqueous maltose solution.

The gastro-resistant coating can be carried out by successive filming of a substance such as cellulose acetophtalla.

Claims (3)

 Process for the galenic preparation of an active insulin by the oral route, characterized by the use of: insulin sweating in multivesicular liposomes ensuring the stability of insulin in the intestinal medium; lyophilization of these multivesicular insulin liposomes; a distribution of the lyophilisate in capsules; of an enteric coating of the final pharmaceutical form. 2) Method according to claim 1, using a - for the formation of multivesicular liposomes of 0.450 mole of phosphatidylethanolamine, 0.450 mole of cholesterol, 0.100 mole of phosphatidylserine, 0.100 mole of triolein in 100 liters of a mixture chloroform and ether in equal proportion; 150 grams of insulin crystallized in 100 liters of an aqueous 0.15 M maltose solution; and 500 liters of a 0.20 M aqueous maltose solution; b - lyophilization of the liposomal preparation; c - a distribution of the lyophilisate in capsules; d - an enteric coating of the capsules thanks to successive filming of a substance such as cellulose acetophtallate. 3) Method according to all of the preceding claims, ensuring a staggered release of insulin over time, since all the phospholipid structures constituting the liposomes do not lyse in a single instant.