The present invention relates to pharmaceutical preparations of biologically active peptides and proteins suitable for enteral administration.

As a result of recent progress in the field of biochemistry, many biologically active peptides and proteins are now available for clinical use. However, because they are proteins of low lipophilicity and can be destroyed in the

10 gastrointestinal tract by enzymes capable of cleaving peptide bonds and in the stomach by acid hydrolysis, methods of administering these compounds orally have not kept pace with their synthesis and identification. Typical of this situation is the case of insulin. It has long been ,,- established that insulin is an effective endogenous hormone useful in the treatment of diabetes mellitus. Furthermore, the intact insulin molecule is known to pass through the intestinal wall of various animals under specified conditions. However, adult animals (including humans) absorb 0 insulin poorly when it is orally administered. This is probably due to a combination of factors: destruction of intact insulin molecules as previously discussed and slow passage of intact insulin molecules through the intestinal wall because of low lipophilicity. Consequently, therapeutic use of insulin is limited by the necessity of administering 5 it parenterally, particularly by intravenous or intramuscular injection.

The desire to avoid parenteral administration of insulin ^* has stimulated research efforts in other modes of 0 administration, among which oral ^* administration is the most attractive. Although efforts have been made to develop oral

~ hypoglycemic agents other than insulin, a great deal of effort has also been concentrated on the modification of insulin in such a way that an immunologically intact and metabolically competent insulin molecule can be absorbed -. through the intestine so that insulin itself or a derivative thereof may be orally administered. The search in this area has been concentrated in three directions: the development of adjuvants, the co-administration of enzymatic inhibitors, and the development of liposomes. Adjuvants used with _{ι n} insulin include resorcinols, non-ionic surfactants such as polyoxyethylene oleyl ether, and n-hexadecyl polyethylene ether. Enzyme inhibitors include pancreatic trypsin inhibitor, diisopropylfluorophosphate (DFP) , and trasylol. Liposomes include water-in-oil-in-water insulin emulsions as m r. well as conventional liposomes.

The co-administration of enzyme inhibitors has had some degree of success, particularly when used with duodenal administration. Adjuvants such as hexylresorcinol have been administered with insulin to diabetic patients to give _n systemic, hypoglycemic effects. However, some adjuvants are limited to successful intra-jejunal administration. Compared to the other types of oral insulin preparations, liposomes have been relatively successful. Several studies have shown systemic, hypoglycemic effects after administration of a _l _ liposome containing insulin (e.g. , Patel et al, FEBS Letters,

<z-D

62, 60 (1976); Hashimoto et al, Endocrinol., Japan, 26_, 337

(1979) ) . However, liposomes are still in the development stage of their use as oral hypoglycemic agents and face

' continued problems of stability, shelf-life, and so forth.

_ ₀ The difficulties of-preparing other peptide and protein hormones (and other biologically active peptides and proteins) for oral ingestion or other types of enteral

O:?

-, administration parallel the problems associated with insulin. Accordingly, there remains a need for a composition generally capable of effecting the oral administration of biologically active peptides and proteins. _c - The present invention relates to an enterally effective biologically active peptide or protein composition, comprising: a sandwich complex comprising a hydrophobic core complex of a biologically active peptide or protein with an -, _Q alkyl or alkenyl sulfate having 6-24 carbon atoms and 0-3 double bonds which forms an electrostatic complex with a soft quaternary ammonium ion of the formula NR 1R2R3R4 wherein

R represents a C..-C, --alkyl group;

,r R 2 and R3 independently represent hydrogen or a

C.-C. ₂ -alkyl group; and

R represents hydrogen or a radical of the formula:

20 -ry - iQ t _j t where R is hydrogen, C.-C,. n-alkyl group and R is a linear alkyl or alkenyl group having 6-22 carbon atoms and

0-3 double bonds; or R 1 and R2 together represent a divalent radical

25 of the formula:

—CH_CH_CH_CH_— i —CH-CH-CH-CH-CH-—,

-CH=CH-N=CH-, or CH ₂ CH ₂ OCH ₂ CH ₂ - and

R and R have the meanings previously defined

30 with the provisos that R 1, R2 or R3 may optionally be substituted with a hydroxyl group or an alkoxyl group of the formula -OR 4 where R4 is an alkyl group having 1-4

carbon atoms, that when R1 and R2 together represent a divalent radical, said radical may be substituted by hydroxyl, R 1, or -OR4, and that when R2 is hydrogen,

R is not methyl.

The present invention invovles a method of modifying a biologically active protein in such a way that the protein is absorbed into the systemic circulation when administered enterally, particularly orally, while remaining immunologly intact and metabolically competent. To achieve

10 this result, the protein is coupled to a protective carrier in the form of a sandwich complex described in a later section. To be successful in this role, the protein complex must meet the following criteria: (a) it must be resistant to the acidic environment in the stomach; (b) it must be ,,- resistant to enzymatic degradation by gastric and pancreatic enzymes; (c) it must be sufficiently lipophilic to pass the intrinsic barrier of the intestinal wall; and finally (d) the changes in physiological and biological properties of insulin molecules resulting from the modification must be minimal SO

20 that their hormonal activity is maintained. While criteria (c) and (d) are basic structural requirements for all enterally administered proteins (such as by rectal, buccal or topical routes) , criteria (a) and (b) must be met in addition to (c) and (d) for the protein to be orally effective.

25 More specifically, the present invention provides a sandwich-type complex of a biologically active peptide or protein with an alkyl sulfate and a soft quaternary ammonium ion. The biologically active peptide (hereafter "peptide" or "protein" will refer to both peptide and protein molecules

30 unless otherwise indicated) first forms a hydrophobic core complex with the alkyl sulfate. This core complex protects

.. the peptide molecule from acidic hydrolysis and enzymatic degradation and increases the lipophilicity of the peptide molecule, thereby allowing the intact peptide to pass through the stomach when orally ingested and to increase the rate at

-. which it is absorbed; through the intestine wall. This inner complex may be formed between the peptide molecule and the alkyl sulfate. Hydrophobic complexes of•a peptide with an alkyl sulfate are generally rod-like with a helical polypeptide chain of the peptide existing within a hydrophobic shell formed by the alkyl sulfate. Typical of alkyl sulfate complexes with protein are those complexes formed with sodium dodecyl sulfate (SDS) . SDS has been found to bind protein molecules in constant gram to gram ratios irrespective or nature of protein but depending on the SDS monomer concentration. When SDS monomer concentration

4 exceeds 5 x 10 M, proteins form complexes with SDS in a high binding ratio' where one gram of protein binds to about

1.4 gram of SDS. When the SDS monomer is less than 5 x 10 -4M, proteins form complexes with SDS in a low binding ratio where one gram of protein binds to about 0.4 gram of

SDS. Both protein SDS complexes assume a similar, rod-like shape with a helical polypeptide chain or protein folded back upon itself near its middle to give a double helical rod and the SDS forming a shell about the rod via hydrophobic forces.

The sulfate groups of SDS are on the surface of the rodlike complexes as evidenced by the electrophoretic migration of insulin in the presence or in the absence of SDS. In electrophoresis at pH3 in the absence of SDS, insulin is fully protonated and migrates to cathode. In the presence of

SDS (0.1%) at pH 3, insulin migrates to the anode (as if it is an anion) .

-. Since alkyl sulfates are themselves hydroylzed to fatty acid alcohols and a sulfuric acid salt at acidities approximately those of the stomach, the rod-like peptide alkyl sulfate complex requires an additional protective _c - coating for oral administration which is provided by a soft quaternary ammonium ion, the structures of which are described later in detail.

By utilizing the method of the invention, it is possible to prepare peptide compositions suitable for oral

, ₀ administration which contain endogenous opioid agonists, such as encephalins and endorphins; hypdthalmic hormones, such as gonadoliberin, melanostatin, melanoliberin, somatostatin, thyroliberin, substance P, and neurotensin; adenohypophyseal hormones, such as corticotropin, lipotropin, melanotropin,

..-- lutropin, thyrotropin, prolactin, and somatotropin; neurohypophyseal hormones; calcitropic (thyroid) hormones, such as parathyrin and calcitonin; thymic factors, such as thymosin, thymopoietin, circulating thymic factor, and thymic humoral factor; pancreatic hormones, such insulin, glucago ^' n, _pn and somatostatin; gastrointestinal hormones, such as gastrin, cholecystokinin, secretin, gastric inhibitory polypeptide, ^' vasointestinal peptide, and motillin; chorionic (placental) hormones, such as choriogonadotropin and choriomammotropin; ovarian hormones, such as relaxin; vasoactive tissue .- hormones, such angiotensin and brandykinin; growth factors, such as so atomedins, epidermal growth factor, urogastrone, and nerve growth factor; hemophilia factors, such as blood clotting factors VIII and IX; enzymes, such as streptokinase, fibrinolysin, deoxyribonuclea.se, and asparaginase; and

30 artificial or pseudo peptides, such as deferoxamine. Many other classes and specific types of peptide and protein hormones and other biologically active molecules are known.

Peptide and protein hormones suitable for use in the present invention are disclosed in Johannes Meinenhofer, "Peptide and

Protein Hormones", in Burger's Medicinal Chemistry, 4th ed. ,

(part II), Wolff, Ed., John Wiley and Sons (1979), which is herein incorporated by reference. Preferred hormones are those with a molecular weight of less than 7000, with insulin being especially preferred.

The listings of peptides and proteins in this application are not intended to be exclusive, and it may easily be determined by simple experimentation if any protein having biological activity can be prepared into a complex according to the invention. One simple method of testing for core complex formation involves the following steps: (1) dissolve approximately 10 g of the biologically active peptide or protein in a small amount of water or buffer; (2) adds about 15 mg of an alkyl sulfate, for example sodium dedecyl sulfate, mix well and allow to stand for about 5 minutes; (3) subject the resulting solution to agarose or acrylamide gel electrophoresis. The complex acts as an anion even at low pH (about 3 is a good testing point) because of the sulfate gruops and migrates towards the anode. If no complex has formed, the protein will be protonated at low pH and migrate toward the cathode.

If complex formation has taken place and if the resulting core complex will itself complex with a soft quaternary ammonium ion according to the process of the present invention (infra) , the biologically active peptide is suitable for use in the present invention.

Complex formation between protein and a carrier molecule is one way to protect a protein molecule from acidic hydrolysis and enzymatic degradation and to increase the lipophilicity of the protein molecule. Depending on the

carrier substances selected, formation of this complex can be via columbic interaction between protein molecule and carrier substance or via hydrophobic forces. In the proposed ^' sandwich complex of protein:alkyl sulfate soft quaternary ammonium ion, there is a "core" complex of protein and alkyl sulfate formed via hydrophobic forces, and there is electrostatic attraction between the sulfate groups of the alkyl sulfate and the soft quaternary ammonium ions.

Unlike other chemical, modifications, complex

10 formation between an agent and a carrier substance is a molecular modification of the agent without any chemical alteration of the molecule itself. It is a method of modification in which the biological integrity of the molecule remain more or less intact. This is especially true

, r- in complexes formed via columbic forces.

Alkyl sulfates useful in the present invention have linear, branched, or cyclic alkyl groups having 6-24 carbon atoms. Of these, linear alkyl groups, preferably with 8-18 carbon atoms, are preferred, especially those having an even

_P0 number of carbon atoms. Alkenyl sulfates having 1-3 double bonds are also suitable. Specific examples of suitable alkyl and alkenyl sulfates include octyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl, 10-methyloctadecyl, 4-hexylcylohexyl, 9-octadecenyl, 9,12-octadecadienyl, r- 9,12,15-octadecatrienyl, and tetracosyl sulfate.

Sulfates of the invention can be synthesized by standard methods of synthesis using alcohols (e.g., fatty alcohols) and sulfuric acid or sulfate salts. Many alkyl sulfates, e.g., sodium dodecyl sulfate, are commercially

30 available. Suitable examples of preferred linear alkyl sulfates include octyl sulfate, nonyl sulfate, decyl sulfate, undecyl sulfate dodecyl sulfate, tridecyl sulfate, tetradecyl

-, sulfate, pentadecyl sulfate, and hexyl sulfate. Of these, decyl sulfate, dodecyl sulfate and tetradecyl sulfate are more preferred with dodecyl sulfate being most preferred.

The alkyl sulfates are generally present initially r- as alkali metal salts when the initial core complex is being formed. Alkali metal salts include lithium, sodium, potassium, rubidium and cesium salts. Of these, sodium and potassium are preferred, with sodium salts being most preferred. Sodium and potassium salts of dodecyl sulfate are

-. _Q especially preferred, with sodium dodecyl sulfate being the most preferred alkyl sulfate salt.

The weight ratio of protein or peptide to alkyl sulfate is the weight ratio of the naturally forming complex. In a preferred embodiment, insulin is complexed with sodium

-,[- dodecyl sulfate (SDS). This complex forms an insulin:SDS complex in a ratio of 1:1.4 or 1:0.4 by weight (depending on the initial ratio present) and is a hydrophobic complex. Complexes of protein with SDS are preferred to other types of complexes because a wide variety of proteins are reported ^" to

2 bind to an identical amount of SDS on a gram per gram basis. See, for example, Reynolds et al. , Proc. Nat. Acad, Sci. ^' (US) , j> , 1002-1003 (1970) and Reynolds et al. , J. Biol. Chem. , 245, 5161-5165 (1970) . When SDS forms a complex with insulin or other protein, the hydrophobic core complex is p _c rod-like with a helical polypeptide chain of protein existing within a hydrophobic shell formed by the SDS. This complex of protein with alkyl sulfate is preferred to herein as a core complex. THis term is not intended to limit the present invention, but is believed to be generally descriptive. When

30 this core complex is itself complxed with a soft quaternary ammonium ion, an additional layer forms on the surface of the inner complex. This latter complex is referred to as an

"electrostatic" complex. Nevertheless, this term additionally is not intended to be a limiting of the actual physical structure that is present in the resulting complex.

As mentioned above, the inner complex is reached with a soft quaternary ammonium ion to form an outer complex. The phrase "soft quaternary ammonium ion" as used in this invention includes protonated organic amines and other amine derivatives as will later be defined. A suitable amine from which to form a protonated amine of the invention has the 0 formula NR 1R2R3 wherein R1 represents a

C- -C. --alkyl group and wherein R 2 and R3 independently represent hydrogen or a C.-C. _-alkyl group. Representative alkyl gorups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, pentyl, neopentyl _C m hexyl, heptyl, octyl, nonyl, decyl, undecyl, and dodecyl.

- ^? Additionally, R1 and R2 together can represent a divalent alkylene radical which, when taken together with the amine nitrogen, forms a 5- or 6-membered ring. Examples of suitble radicals include -CH_CH ₂ CH ₂ CH ₂ -, ₀ -CH ₂ CH ₂ CH ₂ CH ₂ CH ₂ ~, and derivatives of these radicals having an alkyl gropu of formula R in place of one or two hydrogen atoms of said radical. Furthermore, R

2 and R when taken together with the amine nitrogen may form an imidazole or morpholine having the formula 5

0 Additionally, any of the substituents R 1-R3 previously defined may be substituted with a hydroxyl or alkoxyl group,

-x wherein the alkoxyl group has the formula -OR4 where R4 is an alkyl group having 1-4 carbon atoms. It is preferred that the amine contain a total of 3-15 carbon atoms with 6-10 carbon atoms being more preferred. Specific examples of

.- suitable amines include trimethylamine, triethylamine, n-propylamine, methyldiethylamine, diethyla ine, methylbisethoxyethylamine, methyl-4-hydroxybutylpentylamine,

N-methylpyrrolidine, N-ethylimidazole, and morpholine.

Preferred amines include trimethylamine, triethylamine,

, _Q tripropylamine, morpholine, N-alkylimidazoles, and

N-alkylpyrrolidines. The amines used in this invention are readily available either commercially or through standard methods* of synthesis. Methylamine and dimethylamine should specifically be avoided because of the carcinogenic products

-, r- formed when they react with nitrites under acidic conditions (e.g. , in the stomach) ^* .

When the amines of the invention are formulated' into the outer complex, they are present as protonated amines. Preferred are amines protonated with mineral acids" 0 such as, for example, sulfuric acid and hydrochloric acid. However, organic acid salts, such as salts of oxalic or lactic acid, may also be used. Amine hydrochlorides are especially preferred.

In addition to protonated amines, other soft quaternary ammonium ions may also be used to form the 5 electrostatic complex of the invention. By soft quaternary ammonium ion is meant an ion of the formula

0

R ² -N-CH-0-C-R ⁶

R ³ R ⁵

5

OΛJPΓ

where R1-R3 have the meanings previously given, R5 is hydrogen, methyl or ethyl and R is the alkyl or alkenyl residue of a naturally occurring fatty acid of fromula R 6CO.H. R6 may additionally be any linear alkyl group having 6-22 carbon atoms or any linear alkenyl group having 6-22 carbon atoms and 1-3 double bonds. Other quaternary ammonium ions which hydrolyze or are otherwise cleaved to release harmless organic compounds are contemplated as equivalents. The principal requirement of a soft quaternary ammonium ion is the ability to lose its positive charge in a biological system by deprotonation, hydrolysis, or enzymatic degradation.

In the acidic environment of the stomach, a soft quaternary ammonium ion of the previously given formula in a sandwich complex will hydrolyze to give a fatty acid, an aldehyde and a (protonated) substituted ammonium ion and leave an unprotected "core" complex of protein: alkyl sulfate. Depending on the rates of hydrolysis of the sulfate to an alcohol and acid sodium sulfate and of the protein itself, an electrostatic complex may form between the "core complex and the protonated sub¬ stituted ammonium ion generated in situ.

In other words the soft quaternary ammonium ion of the given formula is designed here not only for its added lipophilicity due to the presence of the ester moiety, but also so that once it is hydrol zed in an acidic environment, another "soft" quaternary ammonium ion, in this case, a -protonated amine, takes its place to provide continued protection for the hydrophobic "core" complex.

BUKE-

The synthesis of a soft quaternary ammonium ion involves two steps, the preparation of an <* -chloroalkyl ester, and the formation of the desired quaternary ammonium ion:

_{R D} _C-ci ₊ RS -C-H ¹ ° °" ^C ■ α— chloroethyl ester

Since a soft quaternary ammonium ion is a positively charged reagent and since the alkyl sulfate is a negatively charged reagent, a 1:1 molar ratio of the soft quaternary ammonium ion with the alkyl sulfate is preferred. However, other ratios are possible and fall within the scope of the invention. Ratios of amine to alkyl sulfate in the range from 1:0.3 to 1:1 are contemplated by the present invention. Such ratios are obtained by using an excess of the core complex or the amine/ammonium ion component during formation of the electrostatic complex.

The final electrostatic complex is formed by adding the soft quaternary ammonium ion to an aqueous solution containing a protein.alkyl sulfate complex (i.e., the core complex) . The resulting electrostatic complex comprising the entire protein,alkyl sulfate.soft quaternary ammonium ion complex can be isolated by extracting the aqueous solution with chloroform or another non-polar solvent immiscible with water. The presence of protein in the extracted complex can be verified using the Fluorescamine protein test as described in Udenfried et al, Science, 178, 871-872 (1972) , which is herein incorporated by reference. When working with a previously untried complex, this allows easy verification of the formation of the desired complex.

This invention may be carried out either by preparing a pharmaceutical composition which may be stored in that form or by producing the. sandwich complex immediately prior to administration. When a protonated amine is used to form the final complex, the complex can be stored at approximately 4°C in 0.005 M phosphoric acid for at least 2 weeks. When a soft quaternary ammonium ion is used, the complex should be prepared in deionized water at a pH of approximately 7. It can then be lyophilized and sto-red in powder form for at least several months. Since oral administration is the prin¬ cipal contemplated end use of the -compositions of the present invention, compositions suitable for oral inges- tion are preferred storage forms. Such compositions can contain pharmaceutically acceptable carriers in addition to the previously disclosed ingredients. Suitable pharmaceutically acceptable or otherwise inert materials which may be used orally. Examples of liquids are water and aqueous solutions of non-toxic salts, such as sterile physiological solutions of saline, or aqueous solutions containing non-toxic organic solvents, such as ethanol, used to increase the amount of complex in solution. Dilute aqueous solutions of mineral acids having a pH of less than 4 are also suitable. Phosphoric, sulfuric, and hydrochloric acids are preferred. Also suitable are emulsions, such as oil-in-water emulsions. Solutions of non-toxic organic liquids, such as ethanol, are also suitable. Solid carriers include both nutritive carriers, such as sucrose or gelatin, and non-nutritive carriers, such as cellulose or talc. A pharmaceutical preparation of the invention may be in the form, for

example, of a liquid, a capsule, a tablet, or a suppository.

Pharmaceutical compositions according to the present invention are administered in dosages which depend upon the effect desired for the biologically active compound which is being administered. The determination of the effective amount of the biological compound is not con¬ sidered to be part of the present invention since dosage rates are generally determined by the effect of the composition on the particular patient taking the med¬ ication. An amount equal in dose rate ( g/kg) to the amount normally injected parenterally for known bio¬ logical active peptides is suitable for use in the present invention as an initial dose and may be adjusted as necessary to achieve the desired effect. A particularly preferred embodiment of this invention comprises enterally administering a sandwich complex of the Invention containing insulin as the active ingredient to produce a hypoglycemic effect. The amount required will depend on the severity of the diabetes and on the condition of the pateint (e.g., time since in¬ gested, etc.). Adjustemnt of the amount required to main¬ tain the proper blood glucose level is within the capability of those of ordinary skill in the art. An orally admin¬ istered sandwich complex (of insulin or any other active peptide) is especially preferred.

The above disclosure generally describes the present invention. A more complete understanding can be obtained by reference to the following specific examples which are not intended to be limiting unless otherwise specified.

/^BUR£4

' O PI

Example 1

1 An insulin sandwich complex comprising insulin: sodium dodecyl sulfate:triethylamine hydrochloride in a weight ratio of 5:7.5:3.6 was prepared. Insulin (bovine pancreas, crystalline; 25.5 u/mg; Sigma; 10 mg total) was

5 dissolved in a small amount of 0.005 M H_PO. , pH 2.45, in a 5 ml volumetric flask. Sodium dodecyl sulfate (15 mg) was added and mixed well to give a clear solution. After the solution was allowed to stand for 5 minutes, 7.2 mg of triethylamine hyrochloride was added. The volumetric ° flask was then filled to 5.0 ml with 0.005 M H PO., pH 2.45 to give the final insulin:SDS: EA complex.

Example 2 In Vivo Tests of Sandwich Complex

The term "diabetic rat" in the following tests refers to rats having been treated with streptozoticin by intra¬ venous injection at a dosage of 75 mg/kg at least 4 days prior to the experiments in question. All rats used in the experiments had been fasting 12-18 hours prior to the exper¬ iments. Blood samples were taken at appropriate intervals as disclosed in the tables from a vein cannula which was implanted in a juglar vein. During the experiments, rats were awake, were able to 'move freely and had access to water (but no food) . Plasma glucose was measured on a Beckman Glucose Analyzer 2 employing the enzymatic reaction of -D-glucose with oxygen and measuring oxygen consumption rather than hydrogen peroxide formation. A. Intravenous (iv) Administration of Regular and Modified Insulin in Diabetic Rats.

The results f iv administration of regular and modified insulin in diabetic rats are shown in Tables 1 and 2 respectively. Both regular and modified insulin yielded progressive, systemic, hypoglycemic effects for five hours in all animals. From 15 min to 45 min after iv administration, the induced hypoglycemic effect was more pronounced in regular-insulin-treated animals. Then from 60 min to 2 hrs after iv administration, the hypo- glycemic effects among regular- and modified-insulin- treated rats became comparable. After 2 hours, the blood glucose level in the modified-insulin-treated rats returned to the initial level faster than in the regular-insulin- t.reated rats; e.g., five hours after administration, in the modified insulin group 89.1% of the initial plasma glucose concentration was observed while in the regular

0- PI ^' -

insulin group 65.7% of the initial plasma glucose con¬ centration was found.

Among the individual rats treated with both agents, rat #285 showed a progressive hypoglycemic effect after iv administration of regular insulin (4th row in Table 1) , whereas iv administration of insulin:SDS: EA complex only yielded a slight hypoglycemic effect (Table 2, 3rd row). On the other hand, rat -13 showed more pronounced hypo¬ glycemic effect for the first 90 min when the rat was treated with the insulin complex than when it was treated with regular insulin whereas the reverse was true in the later hours (see 5th row in Table 2 vs 6th row in Table 1) .

The data do indicate that insulin in a sandwich- complex of insulin SDS TEA with a weight ratio of 5:7.5:3.6 remains physiologically effective. Compared with the hypo¬ glycemic effect of regular insulin in diabetic rats, the hypoglycemic effect of the modified insulin is not as sustaining. In all likelihood, the presence of a protein denaturing agent, SDS, in the sandwich complex probably reduces the psysiological effectiveness of insulin to a certain extent.

Table I Intrαvenoue λdxlntatratlon of Insulin (O.Su/kj) Into Diabetic Rica

LO H V 1 O VJ1 o H VJ1 o Ul

Table 2 Intravenous Administration of Insulin Complex Into Diabetic Hats (0.5u/kg)

_] _ B. Oral Administration of Regular and Modified

Insulin (at 80u/kg) in Normal and Diabetic Rats.

In order to prove that the systemic hypoglycemic effect observed after oral administration of insulin: c SDS:TEA in diabetic (or normal) rats, if any, is due to the complex per se and not due to the presence of SDS:

TEA nor to nonspecific protein:SDS: EA complexes, oral administrations of insulin:SDS : EA in diabetic rats were run against three controls. The three controls were

-]_ regulars insulin, a carrier complex of SDS:TEA, and a complex of albumin:SDS:TEA in the same weight ratio as than in the insulin complex; i.e., albumin:SDS:TEA=5 :7.53.6.

The results of oral administrations of modified 5 insulin and carrier complex (SDS:TEA-1.1 by mole) in the amount equivalent to that in the sandwich complex of insulin calculated based on 80 u of insulin per kg of rat in normal rats are shown in Tables 3 and 4. The results of oral administrations of modified insulin, regular insulin, 0 carrier complex and the sandwich complex of albumin (albumin: SDS:TEA in a weight ratio of 5:7.5:3.6) in diabetic rats are shown in Tables 5, 6, 7 and 8 respectively.

As shown in Tables 3 and 5, oral administration of modified insulin in both diabetic and normal rats give a 5 systemic, hypoglycemic effect in rats which lasts at least five hours. The streptozotocin treated rats respond to modified insulin to a much greater extent than do normal rats; i-e., the glucose level is about 20% lower (compare Tables 3 and 5) . 0 In contrast, the oral administration of regular insulin does not result in a systemic, hypoglycemic effect in diabetic rats (see Table 6) . The same conclusion can be

drawn from other control studies. Oral administration of the electrostatic complex of SDS:TEA does not yield a systemic, hypoglycemic effect in normal (see Table 4) and diabetic (see Table 7) rats. Nor does the oral adminis- tration in diabetic rats of a sandwich complex of a protein which does not have hypoglycemic effect per se. Likewise, the oral administration of a sandwich complex of albumin: SDS:TEA in the weight ratio of- 5:7.5:3.6 in diabetic rats fails to produce a systemic hypoglycemic effect. ^"* The experimental results reflected in the above data show that by forming a complex with a lipophilic substance like TEA in the form of a sandwich complex of insulin:SDS: TEA, the lipophilicity of insulin is improved. By doing so, metabolically competent insulin molecules are able to pass through the lipid barrier of the gastrointestinal tract and thence into the circulation to produce a progressive, systemic hypoglycemic effect in normal and diabetic rats.

Table 3. Oral Administration of Modified Insulin In Kormnl Rats (80 u/kp.)

Hi _b J _L C (i Ural Administration ol Currier Complex in Normal lints

(The amount of carrier complex is equal to that In complex insulin ^• SDS ^• TF.Λ at 80u/k _β but without inaulin)

I t

*»• I

* Plasma samples were not scored In the Freezer (-20 C), but left at room temperature for three days

ro ro y H

O o o ι

Table 5. Oral Administration of Modified Insulin to Diabetic (Strαptozotocin-trcatod) Rats (80 n/kp,)

I t tn

•M

T

from the toll artery when Cite rat uoo under ether nn-oclilnnUoii. »2. Inoultn aolutlon (1.10 cl of i.l -t lnaulln/1 nil 0.005H IUP0, , pit 2.45) wno probably odnlnlo tcrcd Into the rc-plratory «y cc-» of the rαc tnuceod of tlio otoinnch. Hut ldokcd rather olck for 30 Bin. after odmlnlocriitlon.

s ro ro H y J1 o vn o V O Ul

fable 7, Oral _Λ l»l(ila ration of Carrier Complex In Diabetic (Scrcptαtotoeln Treated) Rate. (The ac->unt of carrier coaplex la equal to that la corsplcx lnaulln ^■ SOS ' TEA at 30u/kg without inoulln.)

Table 8,. Oral ΛJnlnlotratlon of Albumin Complex of Albumin • SDS ^■ THΛ In a i;Ight ratio of 5:75:3.6 In Diabetic (Stroptoιnιo-ln Treated) mm.

I

1-0

CD I

Example 3 Four fi-chloroethyl esters have been prepared and isolated purified in good yield; i.e.,

0 CH ₃ <£/ -chloroethyl n-octanoate (C _g ); CH_- (CH_) g-C-O-CH-Cl

cf -chloroethyl n-nonanoate (Cg); CH.,- (CH ₂ ) _? — 2-O-C S ^H H-Cl

O CH, cy-chloroethyl n-decanoate (C, _Q ) ; CH,- (CH_) ---CC--O0--CCHH--CC1

> -chloroethyl n-dodecanoate (C, ₂ ) ; CH,- (CH ₂ ) _1Q

Two soft quaternary ammonium salts, [1- (n-dodecanoyloxy) ethyl] triethyl ammonium chloride (A) and [1- (n-dodecan¬ oyloxy) ethyl] -3-methylimidazolium chloride (B) , have been prepared by the method previously described in the specification. The toxicity of "1-methylimidazole is very slight (e.g.,- oral Mice LD,., 1500 mg/kg; ipr. Mice ^LD ₅₀ ' ³⁸⁰ ?/- ^k< ?-- ⁾

H NMR (CDC1-) of ammonium ion (A) : 6.6 (quartet,

1H) , 3.2 <=T (quartet, 6H) , 2.3o" (triplet, 2H) , 1.9σ

(doublet 2H) , 1.5<--f (triplet, 9H) , 1.3<S (broad singlet,

18H) , 0 . 9S (triplet, 3H) . H NMR (CDCl,) of imidazonium ion (B) :

10.3«T (singlet, 1H) , 7.8«£ (doublet, 2H) , 7.25 (quartet,

1H) , 4.2 (singlet, 3H) , 2.4o~ (triplet, 2H) 1.9-5

(doublet , 3H) , 1. 4<f ) Broad singlet , 18H) , 0 . 9 ^ (triplet ,

3H) .