Levetiracetam for use in the treatment of pain caused by hydrocephalus

Abstract

Levetiracetam is described for use in the treatment of hydrocephalus and the pain caused by it.

Description

[0001] DESCRIPTION

[0002] Title

[0003] USE OF LEVETIRACETAM FOR THE TREATMENT OF HYDROCEPHALUS

[0004] Technical field

[0005]

[0001] The invention relates to the field of products having pharmacological activity.

[0006] Present status of the art

[0007]

[0002] The incidence of neonatal hydrocephalus is around 3-4 cases per 1,000 live births and is the most frequently treated surgical condition in pediatric neurosurgery. In terms of incidence in relation to age, there are two peaks, one in infancy and one in old age, which is mainly due to chronic 'normotensive' hydrocephalus in the elderly. Hydrocephalus acquired during life is one of the most common neurosurgical conditions and can occur on its own or as a complication of numerous disorders of the central nervous system (CNS). The condition occurs when there is an excess of cerebrospinal fluid in the CNS, where it accumulates under high pressure due to an imbalance between production and reabsorption caused by multiple congenital and acquired factors. From a pathophysiological point of view, it can be divided into three main categories:

[0008] 1. Hypersecretory due to cerebrospinal fluid hypersecretion;

[0009] 2. Obstructive (due to blockage of its circulation, this is the most common type, e.g., due to congenital brain neoplasms obstructing the cerebrospinal fluid pathways or vascular malformations);

[0010] 3. Aresorptive (due to defective reabsorption, as in the case of blockage and sclerosis of the villi caused by hemorrhagic or infectious events).

[0011]

[0003] Considering that the total amount of cerebrospinal fluid in the adult CNS is 100-150 ml, of which 15-25 ml is contained within the ventricular cavity, it can be concluded that the entire cerebrospinal fluid is completely replaced approximately 3-5 times per day and that therefore even the slightest alteration in this delicate process can lead to hydrocephalus.

[0012]

[0004] To date, treatment has been aimed at directly removing the cause of the blockage in cerebrospinal fluid circulation, such as the removal of a tumor obstructing the fourth ventricle or compressing the aqueduct of Sylvius, or the excision / perforation of obstructing arachnoid cysts.

[0013]

[0005] Unfortunately, in most cases, this causal approach is not feasible, requiring surgical intervention to divert the cerebrospinal fluid from the ventricular system to locations where it can be reabsorbed, bypassing the site of obstruction, or outside the skull to other body cavities such as the peritoneum or cardiac atrium (extracranial shunts).

[0014]

[0006] The advent of ventriculoperitoneal and ventriculo-cardiac shunts has significantly changed the prognosis of infantile hydrocephalus, leading from an unacceptable mortality rate (up to 80%) recorded in the past to better prospects in terms of survival (greater than 80% at 5 years after surgery) and quality of life (Q) within normal limits in about 50% of cases. Over the years, increasingly sophisticated valves have been designed (low, medium, or high- pressure valves, valves with anti-siphon systems, and even valves with externally adjustable opening pressure using magnetic systems) to minimize the phenomenon of hyperdrainage that occurs when the patient moves from a supine to an upright position. Hyperdrainage causes numerous complications such as hygromas and subdural hematomas, craniostenosis, cranioencephalic disproportion, etc.

[0015]

[0007] This type of approach, which still requires surgery, is not without complications in fact, in addition to these complications, there are others that affect the cerebrospinal fluid drainage systems, among which mechanical complications are particularly frequent (obstruction of ventricular or peritoneal catheters, rupture, disconnection, and migration of distal catheters), followed in frequency by infectious complications due to surgical contamination (especially Staphylococcus epidermidis and aureus), which are particularly dangerous in terms of neurological outcome and mortality. Over the last twenty years, various neuroendoscopic procedures have been introduced that are effective in the treatment of pure obstructive hydrocephalus caused by anatomical stenosis of the cerebrospinal fluid circulation pathways. These innovative treatments have reduced the need for extracranial cerebrospinal fluid shunts, but unfortunately they are not always effective, especially in children under 12 months of age with open skulls, and in forms of nonobstructive communicating hydrocephalus, especially when associated with tumor (meningeal carcinomatosis), infectious, or hemorrhagic etiology.

[0016]

[0008] To date, the pharmacological approach to hydrocephalus is only supplementary to surgical treatment, and the drugs used solely as palliative and temporary therapy are:

[0017] 1. Diuretics: primarily acetazolamide, as furosemide and mannitol have a mild effect in reducing cerebrospinal fluid (CSF) production. Acetazolamide is a carbonic anhydrase inhibitor with side effects that can be serious in cases of prolonged treatment. These include: paresthesia, gastrointestinal disorders, taste disturbances (metallic taste in the mouth), nervous system disorders with drowsiness, fatigue, headache, confusion, dizziness, electrolyte imbalances, metabolic acidosis, and vision and hearing disorders.

[0018] 2. Systemic corticosteroids: used only to reduce periventricular edema caused by cerebrospinal fluid transudation linked to hydrocephalus, and peri-lesional edema (peripheral inflammation in tumors and other space-occupying processes) due to disruption of the blood-brain barrier.

[0019] 3. Drugs for managing the symptoms of hydrocephalus, such as headache and vomiting, which are therefore not curative.

[0020] In light of the above, the availability of a drug capable of reducing cerebrospinal fluid accumulation would represent an important innovation in avoiding all the consequences described in relation to surgical practice, even the least invasive, as well as for the benefit of the patient, who would not have to undergo surgery, and consequently for families, also for economic reasons. There are also some conditions in which hydrocephalus may be temporary (acute hemorrhagic events, hydrocephalus in premature infants) where neurosurgery is not always strictly necessary, or internal medical conditions (anticoagulant therapy, cachectic states, systemic and cerebrospinal fluid sepsis) in which surgery is contraindicated.

[0021]

[0009] Levetiracetam [IUPAC name 2S-(2-oxopyrrolidin-l-yl)butanamide] is a well-known drug belonging to the racetam family, compounds characterized by the presence of the 2- pyrrolidone ring and whose nootropic action is well known and widely used.

[0022]

[0010] These drugs are capable of significantly increasing learning abilities and intervene in other cognitive mechanisms, but no activity on hydrocephalus has been reported.

[0023] In RUXMOHAN SAMIR et al. "Refractory Epilepsy in a Toddler with PPP2R1A Gene Mutation and Congenital Hydrocephalus," CUREUS, November 29, 2021 (2021-11-29), X P093277685, ISSN: 2168-8184, DOL:10.7759 / cureus.19988 describes the use of levetiracetam for the treatment of epilepsy in a young patient suffering from various diseases, including hydrocephalus. The document does not highlight any relationship between a possible therapeutic or pain-relieving effect of levetiracetam on hydrocephalus and / or the pain caused by it.

[0024] Objects and summary of the invention

[0025] [Oil] The present invention relates to the use of levetiracetam for the treatment of hydrocephalus and, more specifically, concerns the use of levetiracetam for reducing the accumulation of cerebrospinal fluid in the intracranial space and the somatic pain associated with the abnormal increase in this fluid. The use of levetiracetam according to the present invention allows effective intervention in hydrocephalus without necessarily resorting to surgery.

[0026] Brief description of the drawings

[0027]

[0012] Fig. 1 - Effect of repeated administration of levetiracetam on ventricular enlargement induced by hydrocephalus (data are expressed as mean + S.E.M. of 3 animals per group (** p<0.01 vs. vehicle;AAp<0.01 vs. kaolin).

[0028] Fig. 2 - Representative images of ventricular morphology in the three experimental groups: control (vehicle), hydrocephalus (kaolin), and hydrocephalus treated with levetiracetam (kaolin + levetiracetam 600 mg / kg).

[0029] Fig. 3 - Representative images of the condition of astrocytic cells in the cerebral cortex in the three experimental groups: control (vehicle), hydrocephalus (kaolin), and hydrocephalus treated with levetiracetam (kaolin + levetiracetam 600 mg / kg). The astrocytes were labeled using the selective anti-GFAP antibody, shown in light gray. The dark gray labeling with DAPI identifies the cell nuclei. The images were acquired with a fluorescence microscope at 20X and 40X magnification.

[0030] Fig. 4 - Evaluation of the gene expression of A) AQP4, B) TNF alpha, and C) endothelin 1 in the choroid plexuses by RT-PCR. Data are expressed as mean ± S.E.M. of 6-8 animals per group (*P<0.05 and **P<0.01 vs. vehicle;AP<0.05 andAAP<0.01 vs kaolin).

[0031] Fig. 5 - Effect of repeated administration of levetiracetam on hydrocephalus-induced neuropathic pain. The pain threshold was assessed using a) a non-painful mechanical stimulus (von Frey test) and b) a non-painful thermal stimulus (cold plate test). Data are expressed as mean ± S.E.M. of 5 animals per group (**P<0.01 vs vehicle;AAP<0.01 vs kaolin).

[0032] Detailed description of an embodiment of the invention

[0033]

[0013] It has now been surprisingly found that levetiracetam is able to reduce the accumulation of cerebrospinal fluid and therefore allows intervention on the pathology, avoiding all the consequences described in relation to surgical practice.

[0034]

[0014] It is also able to reduce the pain associated with the abnormal increase in cerebrospinal fluid at the intracranial level.

[0035] Part

[0015] The protocol described in the literature by Chen et al. (Chen et al., Fluids Barriers CNS. 2022 Nov 27;19(1):95. doi: 10.1186 / sl2987-022-00393-l) was followed. This model consists of disrupting cerebral cerebrospinal fluid dynamics by injecting 60 pl of a 250 mg / mL kaolin solution into the cisterna magna. This negatively affects cerebrospinal fluid drainage, and its accumulation leads to a progressive increase in intracranial pressure with consequent ventricular dilatation. Brain damage also has a negative impact on the pain threshold; in fact, animals injected with kaolin show a progressive alteration of the pain threshold with the development of thermal and mechanical allodynia measured using the cold plate and von Frey tests. This model has validated the efficacy of levetiracetam in the treatment of hydrocephalus and the neuropathic pain associated with it.

[0036] Example 1

[0037]

[0016] Following the above model, a model of hydrocephalus was induced in 21-day-old rats. Two weeks after the induction of the damage, daily treatment with levetiracetam 600 mg / kg began and continued for the following three weeks. After one and three weeks of treatment (three and five weeks after kaolin insult, respectively), behavioral assessments of somatic pain were performed. At week five, the animals were sacrificed for ex vivo analysis to evaluate the therapeutic efficacy of levetiracetam in modulating the mechanisms involved in hydrocephalic pathology.

[0038]

[0017] Following three weeks of repeated treatment, which began once the pathology had established itself (two weeks after the damage caused by kaolin), ex vivo analysis (performed on coronal sections of the brain in Figure 14 of the Paxinos anatomy atlas) showed a statistically significant reduction in kaolin-induced ventricular enlargement in animals treated with levetiracetam (kaolin + levetiracetam group) compared to animals that did not receive treatment (kaolin group). The data obtained are shown in the histogram (Figure 1), while Figure 2 shows representative images, one for each experimental group.

[0039]

[0018] On the sections used for ventricular morphological analysis, a further evaluation was performed on the status of cortical astroglial cells by immunofluorescence staining. Astrocytes play a key role in maintaining fluid homeostasis in the CNS, and their quantification and morphological evaluation is known to be an important marker of pathological states.

[0040]

[0019] As shown in Figure 3, at both 20X and 40X magnification, animals with kaolin-induced hydrocephalus damage show clear signs of astrocytic distress in the cortex. Co-staining with GFAP (glial fibrillary acidic protein) allows astrocytes to be visualized, which appear less numerous and less developed than in the control group. Repeated treatment with levetiracetam 600 mg / kg leads to an improvement in the status of astrocytes, both in terms of number and structure.

[0041]

[0020] Given the results of the ex vivo analysis, which show that levetiracetam acts both on ventricular volume and as a modulator of astrocytic cells, it is clear that the drug is effective on multiple aspects of hydrocephalic pathology. The investigation into the mechanisms of action of levetiracetam was therefore deepened by conducting a gene expression study on certain markers of interest at the choroid plexus level.

[0042]

[0021] In the kaolin-induced hydrocephalus model, a statistically significant upregulation of AQP4 is observed, as shown in Figure 4A. AQP4 is a protein found in cell membranes that facilitates the transport of water across cells. It is present in various cells in the body, including those in the brain, where it plays an important role in regulating cerebrospinal fluid (CSF) flow. AQP4 is also a cerebral glial marker that marks ependymal cells and astrocyte endings and is the main water channel responsible for parenchymal fluid balance.

[0043]

[0022] The alteration in AQP4 expression found in the hydrocephalus model is normalized by treatment with levetiracetam, suggesting a lower accumulation of cerebrospinal fluid in the ventricles (Figure 4A).

[0044]

[0023] In addition, levetiracetam acts by modulating neuroinflammation; in particular, it has a protective effect in reducing the expression levels of TNF alpha, which increase in hydrocephalus damage, indicating a significant neuroinflammatory state (Figure 4B).

[0045]

[0024] A normalization of the expression levels of endothelin 1, an important vasoconstrictive peptide, was also observed (Figure 4C).

[0046]

[0025] The above findings therefore suggest that levetiracetam has a multifactorial effect capable of acting on multiple aspects of the disease. In particular, the efficacy of levetiracetam can be attributed to an effect on the ventricular enlargement characteristic of the disease, to a modulation of AQP4 and neuroinflammatory processes in the choroid plexuses, and to a modulation of astrocytic cells in the cerebral cortex. A multifactorial effect therefore appears to be the key to the efficacy of levetiracetam in hydrocephalic therapy.

[0047]

[0026] The efficacy of levetiracetam in reducing somatic pain associated with hydrocephalus was thus evaluated.

[0048]

[0027] After one week of treatment with levetiracetam (3 weeks), hydrocephalus-related neuropathy improved in a statistically significant manner. In particular, the animals' response to both thermal and non-painful mechanical stimuli improved, highlighting the anti-allodynic properties of levetiracetam (Figure 5). Continuing treatment for a further two weeks (5 weeks), levetiracetam statistically significantly improved the animals' pain threshold in response to a non-painful mechanical stimulus (von Frey test, Figure 5a).

[0049]

[0028] For the administration of levetiracetam for the treatment of hydrocephalus according to the present invention, the dosages already used for known treatments and similar forms of administration such as tablets, oral solution, and infusion solution can be used. Good results have been obtained with dosages ranging from 600 mg / kg to 6 g / kg.

Claims

CLAIMS1. Levetiracetam for use in treating pain caused by hydrocephalus.

2. Levetiracetam according to claim 1, wherein the levetiracetam is administered to the patient in the form of tablets, oral solution, and infusion solution.

3. Levetiracetam according to claim 2, wherein levetiracetam is administered in amounts ranging from 600 mg / kg to 6 g / kg.

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