IE912431A1 - Composition for the treatment of alzheimer's disease and¹process for preparing the same - Google Patents

Abstract

The present invention relates to a pharmaceutical composition for the treatment of Alzheimer's disease. The composition comprises a synergistic mixture of physostigmin and 4-aminopyridin. A further object of the invention is the process for preparing the above compositions. According to the method according to the invention for treating Alzheimer's disease the patients are administered with effective amounts of physostigmin and 4-aminopyridin.

Description

Th· invention relates to a conpositlon for the treatment of Alzheimer's disease comprising the synergistic mixture of physostigmin and 4-amiao-pyridin as active ingredient. Another object of the present invention le the preparation of the said pharmaceutical composition, λ further object of the Invention is a method for treating Alzheimer's dlssass. backokxhd AM Damages of cognitive functions, the adjustment to recognition of situations in everyday Ilfs la the old age is a frequent diagnosis of dementia. 15,5* of the population IS over 65 and 30* of those over 80 suffers from one of the forms of dementia. Tha Alzheimer's type of dementia has recently become of high professional interest as the disease is associated with elongation of average age and due to the great public interest thereto. 8uoh an interest is obvious as dementia occurs In almost every family. This occurence, however, burdens the families both In social (material) and emotional anpeots. Contrary to the 10 billion in 1982 (Terry and Katsman) 34 billion dollars were spent for nursing patients suffering from any form of dementia in 1985. The number of people connected with the disease exceeded 2,5 million in 1965.

The Alzheimer's disses· was described first by Alois η ΐ «Heimer, German neurologist, in 1906 as a praaenlle type of dementia. The patient, though only 51, showed the most serious symptom» of senile dementia. The deterioration of condition was very rapid and the patient died after a few day·. After autopsy of brain Alzheimer described that the neurofibrils, which, under normal conditions, showed a coordinated, thread-like formation, appeared as an entangled bunch. Th··· neurofibrillar bundle· were described as characteristic symptoms of the disease called ·· presenile dementia, istvin Tarlska (1969) summarized the neuropathological characteristics of the disease entity and called attention to certain symptoms thereof being diagnostically important to distinguish the Alzheimer's and Pick's diseases.

In the sixties, it became obvious that Altheimer's disease appears not only in presemum but also In the late old age and generally comprises a greater part of senile dementis·. The term: Senile dementia of Alshelmer type (SPAT) is generally used. According to thia most modern theory, no difference la made between Alzheimer's disease and senile dementlee, though this theory is sometimes disagreed. It has also been found that the disease entity Is one of the most coneon symptoms. This turn-about is associated not only with the development of the neurological and psychiatric diagnostics, reap., but also the revolutionary development In the health care in the 20th century. This latter resulted In extension of human age, but on the other hand, led to en inoreaae of social and clinical troubles of the old age.

It is well-known that presenile and senile dementia are clinically and pathologically similar. The Alzheimer's disease can appear at any age, however, it forms usually over 50. In case of a definite diagnosis the expeoted mean length of life is 7 years (KoGeer and McOear, 1976}.

The morphological «yeptome of the disease appear ia the area of aeurocortex as well as that of the temporal, parietal and occipital cortex, but symptoms oan also be found in amygdalin and hippocampus. 1. lntraneurally situated neurofibrillar tangles, essentially accumulations of cytosomal neurofllamenta.

Tarlska (1965) describes these as being situated diffusely In certain areas of the brain. 2. intraaeuronal granulovacuolar degenerations end - ) 3. extraneuronal senile (neuritic) argentophyuc plaque·, 4. decrease of cerebral volume and neuron number (about let). Mote, however, that the decrease m the neuron number la ao high over an age of 80 that it la not characteristic for those suffering in Alzheimer* a disease.

The functional symptoms of the disease are ae follows: 1. Dementia A characteristic of the memory disturbance, which is never functional, like In ease of neuropaths and psychopaths, that It extends to all memory components. This disturbance can be Interpreted by serious neurophysiological damages of organic origin. A characteristic symptom is presblophrenla, the complete deterioration of memory: the patient does not remember the happenings of the previous day and even repeatedly reading a text it appears to be novel. Storage of memory traces, turning of short-term memory to long-term memory, i.e. consolidation does not take piaoe, and accordingly, learning, obtaining new knowledge becomes impossible. The loss of manual memory necessary for activity leads to apraxia; e.g., sewing on a button or tiemg a necktie forms an insoluble problem. The early dementia is characterised by the disappearance of the ISO alpha rythm.

The late dementia, however, may be detected even by CT scanning. The emotional disturbances, fear and depression may also be attributed partly to frustrations caused by the forgetfulneaa. 2. Deoline of intelligence Another main group of symptoms of the disease is the rapid decline of intelligence, i.e. that of the standard of proper thinking and the corresponding suitable activity. The patient's mental field narrows down, broader contexts become Immense, the patient adheres to details, cannot make difference between essential and non-essential. Power of discernment, capability of abstraction and combination, aa well as intuition alto decline. Mental work 1« becoming more end more difficult, and in the advanced stage, even carrying out simple household activities gets impossible. {Sometimes serious activity disordes appear: e.g. the patient gets up ln the night and perforata a series of unsuitable activities, turning down and again making the bed, sweeping, etc. Orientation in tine end space and the ability to determine the ego therein decline as well.

The patient becomes unable to follow the dally events, the verbal expression ability gets disturbed and later dlsphaslel (Bchneck et el, 1992), I.e., the loss of Intellectual functions becomes the moat ohareeterlatle symptom. Subsequently, the patient becomes disoriented, apathy, the total insusceptibility to other's feelings, depression, paranoid reactions, hallucinations take place.

The patient nixes up the seasons and cannot use the calender. Sometimes they even cannot recognise their own husband or wife end become totally impossible to sooial life. The disease Is also called double death* referring to the intellectual declining associated with a total physical decay.

The above symptoms may be associated with real psychotic actions, like hallucinations, paranoid reactions, eto. Disturbances can also occur ln the affective (emotional) field: the Initial emotional lability turns into Increasing depression and finally, the patient falls into total lethargy and apathy. All these result ln a slow breakdown of the personality, and, even if somatically the patient Is sometimes in acceptable state, psyohietrloally, the state le near to death. These psychiatric symptoms are followed by neurological ones, like mcontinenoy, motor weakness, extrapyrsmidal symptoms and spasns. Finally, the petlena completely looses the sensibility, the sense of thinking and communicating, and slowly becomes akinetic. The final cause - 5 ef death le generally an intercurrent infection or other chronic disease (Sehneck et al, 1982).

The Alsheimer'a dleeaae le very difficult to diatinguiah fro· othe types of eenlle deaentla. I.e., In the old age, dementia nay he caused hy a number of diaeacea, like arteriosclerosis, apoplexy, tumors, dipsomania, anaemia, undernutrition, thyroid Insufficiency, eto. In these cases, mental deterioration le a secondary process, it le formed on haeie of an other nines·, and accordingly, treatment la equal to curing the original disease. The situation la same with the dementatloa symptoms of Parkinson's disease, paralytic progressiva and senile psychosis. After exclusion of the above symptoms, the Alzheimer's disease should be differentiated from the Kraepelin's disease aad Plekatrophy occuring in the presenlum, which, themselves are also primary dementias. Differentiated diagnosis of both diseases la more or less possible by encephalography, if the presence of all the above diseases can be excluded, the diagnosis of Altheimer'a disease ie probable. According to statistics, about 80% of the senile dementias la of Alshelaer's type.

There are different theories about tho origin of the disease: 1., CEclinera thnorr One of the best known and most important ohemical Impulse conducting materials is the acetyloholln which is released from the chollnerg neurone. The abnormal function of chollnerg system results in lnnumerous disease entitles.

E.g., deficiencies in the cortical chollnerg neuron functions result in Altheimer's disease and myasthenia gravis is prob30 ably in connection with a decreased ohollnerg transmission of motor plate.

There are neurochemical proof· concerning the connection between Alzheimer'a disease and reduced function - 6 of chollnerg system. The activity of cholinacetyl-transferaso (CAT), tha enzyme responsible for acetylchclla synthesis, was significantly lower in biopsy material of brain and In nucleus basalls (Meynert' · nucleus) of autopsy material (Bowen at el, 1976). Lower activities were also found in tha hippocampus. Moreover, an Inverse relationship was found between the frontal - but not parlental CAT activity and the disease (Bowen et al, 1976, Bossor et al, 1964). Consequently, It is right to conclude that lass acetylchoim is released in these cortloal areas. The neural uptake of obolln is also reduced in Alsheimer's disease. The CAT activity Is In Inverse relationship with appearaaee of the senile plaques (Perry et al, 1979).

The cholinesterase (ChE) aotlvlty Is also reduced, it has been established that thsro 1« a olose correlation between the degree of dementia and the defective function of the cholmerg system (Perry et al, 1976). Xt is thought that destruction of the Hissi-stained cells of the basal nucleus, as well as the number of plaques are in close correlation with the severity of the disease entity (Whitehouse et al, 1962). In histological experiments 70t of the nuclei showed degeneration. Though, Perry et al (1982) regarded the destruction of the oytosomes secondary only. The chollnerg feature of these cells was also proved Immunocytochemlcelly (Hagai et al, 1983).

The connection between the oortloal chollnerg system (about 90-60% of nucleus basalls, 20-40 % of lntemeuronal origin) and Alzheimer*· disease is proved by the observation that in Huntington's disease associated with dementia cardinal is as clinical symptom, the CAT activity does not decrease. The binding ability of the cerebral muscarine receptors does not change: there is no difference In 3H-QNB (quinuolidyl bensylete) binding and affinity between brain tissues obtained from normal patients and those died in - 7 Alzheimer’s disease. It is to be noted, however, that no decisive result could be expected fro· this measurement aa only about 109 of the cerebral neurone la chollnerg and the muscarine receptor occurs on neurone of other type as well.

Accordingly, a change in only 109 of the cortical neurone oan result In a minimal change in the chollnerg system only, when taking all binding altea into consideration. Accordingly, data like glycolysis, CO2 production, ate., obtained on the eortex and interpreted aa a result of the modified function of the cholmerg fibers, are hard to aooept. Of course, it holds true for the reverse, I.e., detection of no modification would not mean that the function of chollnerg neurons Is unchanged.

The chollnerg theory is supported by observations that symptoms of patients suffering from Alzheimer's disease are relieved by the ChB-lnhibitmg physostigmln, but aggravated by scopolamine, and there is a close correlation between the cortical CAT-activity (postmortem measurement) and the seriousness of dementia (Nount)oy et el, 1984). 1. Mftgadranarc theory in Alzheimer's disease both the dopaalnerg and noradrenerg pathos are injured. The DOPA-decarboxylase (DOPA-DC, activity la e.g. by 809 lower than on patients with Parkinson's disease (Bowen and Davison, 1978), and of course, also the na and dopaoln content is lower (Gershon and Herman, 1983, Gott fries, 1985). The DA-content la by 609 lower in the hypothalamus. The inhibition of the DA metabolism is characterized by a lower homovanillio acid (HVA) level la these patients (Oottfrles, 1985). Cllnioally detected parkinsonian symptoms, occurmg in 509 of the oases, can be explained by this phenomenon. 1. Qamma-aitliaobnfcvrlo sold Mount Joy et *1 (1984) found that In human a, contrary to the data on rata, th· cerebral GABA level doe· not change postmortem. ho essential correlation was found between the a gaba level in different cerebral areas and the neuropa thologlcal changes. 4. Other theories The disease entity Is also characterised, among other neurochemical modifications, by changes In the somatostatin and other neuropeptide content.

Different methods have been used In the treatment of the disease. Some of them are discussed he rebel ow: i. , hcntYichniin precursor therapy To reduce the defective function of the ohollnerg 13 system, choline, the precursor of ACh la added in high doses (16 g/day). Slmllarlly, phosphatidyl ohollne la also administered (25 to 100 g/day). Moat of these treatments proved to be Ineffective in 'double blind* tests (Jones et al, 1963). Similar reaulta were obtained by the treatment with dsanol (Fishman et al, 1981), which la transformed te ohollne In the liver. Insufficiency of thia treatments is supported by the fact that choline is present in the neurons in a great excess, and accordingly, deficiency seems to be unlikely. 2- Cholinesterase blocking Zn thia treatment decomposition of ACh la inhibited in the synaptio apaoe to enhance the activity of ACh released in a decreased ratio. Pavla et al (1982, 1983) observed interim Improvement after treatment by cholinesterase blocking, in the experiments memory-tests were used. Fhysostigmin, a, 3,3a, β-tstrahydro-l,3a, 8-trimethyl-ptrrolo[2,3-b) indol-5-yl-methyl-carbamate, in a doeis of 6 x 2-2,3 mg/day proved to ba optimal. Unfortunately, administration caused different side-effects (nausea, vomltus). According to other opinions, cholinesterase blocking improves memory disturbance· ln the first line (Mesulam et al, 1987).

Mohs et al (1985) and Hollander et al (1986) also showed Improvement by the administration of physoetigmln. According to the general opinion, however, the improvement le only transitional and provisional (Johns et al). Some selentlsts are oonvlnoed of its inefficiency as beside the deficiencies ln the ohollnerg system likely other neuroohemlcal changes should also play aa important role (Hardy et al, 1985). Formation of memory dlsturbenolee are is likely caused by other neurotransmittance systems as well.

Physoftlgnln was administered to patients suffering from Alzheimer's disease in a dosls of 1 to 1,3 mg/day (Davis et al, 1976, Goodniek end Gershon, 1984) end improvement of cognitive functions was observed. Accordingly, the reduced function of central noradrenerg, aerotoninerg pathea was described. The formation of memory disturbances Is likely promoted by other transmittance systems. Though physostlgmln increases the ACb concentration in the synaptic space, the enhancing effect on the ACh release negative feedback mechanism inhibits the former effect (Vlay et al, 1985). This negative feedbaok inhibition le effected through the muscarine receptors, and accordingly, it can be suspended by atropin. Unfortunately, atropln inhibits the muscarine receptors also postsynaptioally, and thus, though enhancing the ohollnerg transmission by the presynaptlo effect, this favourable effect la Inhibited by the postsynaptlo effect. This theory le supported by the literature describing that administration of atropln damages learning ability and memory i - 10 (Watts et el, 1981), while the same ere ls^roved by the effect of phyaoatiffwin (Murray and piblger, 1988}.

The efficiency of orally administered tetrahydro-ammo-aoldlne (Tacna, tha) is likely also associated with the S cholinesterase blocking effect (Xoopamna, Summon at al, Bngl. J. Mod., Hi, 1341-1241 (1987)). Nilsson et ol (J.Neural Transm., 2SL 357-368 (19871) described that on cortex segments obtained from patients died In Alzheimer's disease both Tacrln and physostigmin enhanced the ACh release. A critical evaluation la described la the April 1989 issue of the British Medical Journal (Lancet, 214, 845-846 (1989)). Multlcontrlo test of Tacrln in the USA, however, was suspended (jarvlk, L.P., Alzheimer's disease and Associated Disorders, A, 133-127 (1987)] duo to hopetoxlc effect of the compound [Wiloock et al, Lancet 1305 (1988)j Arnes et al, 887 (1988)].

Considering all the data obtained from biopsy tests from patients Buffering from Alzheimer's disease, the following information can be summarised: 1, ACh synthesis is under Inhibition (Sims et al, 1980), 2. The number of Mj muscarine receptors Is reduced (Mash et al, 1985), 3. The choline-acetyltransferase activity Is reduced. 4. Postmortem examination of patients died In Alzheimer's disease showed that the nucleus besalls (Meynert nucleus) had been damaged selectively (Whitehouse et al, 1981, Bowen et al, 1976).

These data lead to the conclusion that there la a causal connection between certain symptoms of Alzheimer's disease (cognitive disorders) and the deficit of the choimerg system (Lancet, 139-141 (1987); Cholinergic treatment in Alzheimer*a diseases: Kncouraglng results).

Zt has been found that the 4-aminopyrldln (4-AP) Increases the amount of aeetyloholln released by stimulation - 11 (Viay at al, 1977, FOldes at al, 1988).

Veasling at al. New England Med.J.(1984) described that administration ef 4-amlnopyrldln la Alsheimer'a disease proved to be partially effective. Clinical administration of the ooepound had already been partially known la the following indications: huban botulism Intoxication (Ball at al, 1979), therapy of sclerosis multiplex (Jones et al, 1983, Btefoskl et al, 1987) and in ketamln-dlasepin anesthesia antagonising (Agoston et al, I960). However, Davidson et al [Biol.Psychiatry, U, 485-490 (1988)) found 4-AP In a dally dosls of 2,5 to 10 mg on patients aged 65 ± 10.6 to be ineffective.

DX8CL08UBX OP SUB IBVDITICBf The present invention aims to provide an improved IS therapy to eliminate the diaadvantegoue effects of the above treatments and to provide a pharmaceutical composition which results in an effective therapy by using reasonably low drug concentrations.

The present invention relates to a pharmaceutical composition whloh comprises the mixture of physostlgmln and a-aminopyrldln aa active ingredient. The composition does not poaaeas the disadvantages caused by the negative feedback inhibition caused by the physostlgmln and at the same time the total amount of the two components may be substantially lower than the effective amount of either the phyaoatlgmln or 4-amlnopyrldln when taken alone.

Neurochemloal teats showed that the 4-sminopyridia, a X canal Inhibitor, enhances the ACh release in the cortex (Folds· et al, 19B8) and suspends the negative feedback inhibition, thus promoting ACh release.

Atropin also promotes ACh roleas· «a reaultxng in suspension of the negative feedback inhibition (see Table 1). in the presence of 4-AP which itself also has the same - 13 effect, atropln did not enhance ACh releaf· to e higher level, 1.·., the 82/81 value did not raise. Accordingly, the negative feedback did not function in the presence of 4-AP.

Similar results were obtained at the suspension of the S inhibiting effect of oxotremorln in the presence of 4-AP (see Table 2). Oxotremorln Is e compound stimulating the presyneptlo muscarine receptors as well as Inhibits ACh release. uxkp DucmxrvxaH w dbkrum Pig 1 shows that 4-AP has a higher ACh release increasing effect In the presence of a cholinesterase Inhibitor (Physostlgmia).

BUT MODI TO CAUT OUT ΤΠ INVENTION The above phenomenon might be explained by blocking the negative feedback - which otherwise functions more expressively in the presence of ChK-blooking [Vial et el, J.Pharmac.lxp.Therapy, aao. 493-499 (1984)] - In the presence of 4-AP end consequently, the ACh release is further promoted.

Accordingly, id the composition anoordlng to th· present composition tho phynoohlgmla, which ««» luective due to the enhanced *»y«Liv« feedback inhibition, i.e. destroyed Its own good effect by the function of Its own negative feedback Inhibition, results In enhanced ACh release and prolonged effect. A substantially lower concentration of physostlgmia end 4-amlaopyrldin la sufficient to re-eetablleh the normal chollnerg transmission, l.e. to improve cognitive disturbances. Accordingly, at leaat the most difficult problem caused by Altheimer's disease, l.e. the social breakdown of tho patient can be Improved, at least partly, by the treatment according to the invention. - 11 i ι f i i J I Davidson at al (1968) adniniatered to patients suffering from Alsheimer'a disease aged 66.1 years average 4-amlnopyrldln for four days la a dosls of 6 to 20 mg/day, Wesselln et al (1984) used also an oral dosls of 20 mg/day to patients of 64.6 years average age. Physostlgmln was used in 2x0.8 mg deals by Davis at al (1978).

The composition of the present Invention comprises the synergistic mixture of physostlgmln and 4-aalno-pyridln as active ingredient. The ratio of the components within the mixture may vary within a broad range, preferably it la 1:1 to 1:30. of course, the above preferred ratio may be exceeded In both directions. The suitable weight ratio Is 1:3 to 1:10, most preferably 1:5. λ preferred oral dosls unit contains e.g. 0,2 mg physostlgmln and 1 mg 4-amlnopyrldln, the dally supply being suitably 3 dosls units.

The compositions can ba prepared by methods well-known In the pharmaceutical industry, e.g. by mixing the two active component· with usual formulation auxiliaries and forming the mixture into suitable dosls forms.

The invention also relatea to the process for the treatment of Alsheimer's disease, wherein physostlgmln and 4-amlno-pyridln era added to the patient. Clinical tests showed that the following components and preferred doses should be used: 1. Physostlgsdn salycillcum (Ph.Kg. VZX) preferred dosls: 3x0,2 mg p.ot. 2. 4-aainopyridia (Pymadin, Phansachim, Bulgaria), 3x1 mg p.os, preferably the two components being administered together.

If desired, the 4-amlnopyrldln dosls may ba raised to 3 mg.

Clinical tests carried out on more than 200 patients showed that partial Inhibition of K canal, by the effect cf i - 14 small dosis of 4-AP suspends negative feedback modulation of transmitter release, which, in turn, leads to an enhanced ACh and noradrenalin release, without the appearance of tne characteristic aide effects. Small dosis of physostlgmln S results in a partial cholinesterase Inhibition, but due to the partial Inhibition of the X canal the negative feedback, i.e. the self-inhibiting effect of the ACh on the release la eliminated. This effect is clearly shown on Fig l.

I i I I I i I I - 15 Table l Bat frontal cortex, aH-ACh release la the presence of pbyeostlomin Additive-as2Al no Atropin 0.5 iM 0.53 A 0.06 1,64 3 0.07 4-amiaopyridin 40 jjM 3.36 * 0.13 4-aminopyridln, 40 μΜ + Atropin, 0,5 jM 3.53 X 0.16 j ! Table 3 Bat frontal cortex, 3H-ACh release Additive Se/fli no 0.35 X 0.07 oxotrenorin, 0.3 μΜ 0.48 X 0.03 oxotrenorin, 3.0 /ix 0.32 X 0.03 4-amlnopyridm, 40 tM 1.53 X 0.10 4-aninopyrldin, 40 μχ * oxotrenorin, 0.3 μΜ 1.47 X 0.13 4-anlnopyridln, 40 μΜ ♦ oxotrenorin, 3.0 μΜ 1.42 X 0.11 lfotei 4-aniaopyridin inhibited the 3H-ACh release Inhibiting effect of oxotrenorin.

Claims (7)

1. Pharmaceutical composition for tha treatment of Alzheimer'· disease characterized by containing a synergistic mixture of physostigmin and 4-aminopyrldln as aetive a ingredient.

2. The composition of claim 1 characterized In that the weight ratio of phyeoetigmln to 4-amlnopyridln le 1:1 to 1:20.

3. The composition of 1 or 2 characterized in that the 10 weight ratio of the physostigmin to 4-amlnopyrldln is 1:5.

4. Process for preparing a pharmaceutical composition «y«iu«L Al«h*l**r‘a disease characterised by *1*1 ag a synergistic mixture of physostigmin and 4-aminopyrldln with pharmaceutically acceptable eemera. 15

5. Method for treating Alzheimer's disease characterized by administering to the patient an effective amount of phyaostigmln and 4-amlnopyrldln.

6. The method of claim S characterised by using the physostigmin In a dosis of 0,4-0,5 mg/day and the 420 amlnopyrldln in a dosis of a-4 mg/day.

7. A pharmaceutical composition according to claim 1, substantially as hereinbefore described.