Controlled release compositions of agents that reduce circulating levels of platelets and methods therefor

Abstract

Provided are prophylactic and therapeutic methods of treatment of subjects for the purpose of inhibiting vaso-occlusive events, including embolism, by administering agents, including anagrelide and anagrelide derivatives, which reduce the number of circulating platelets to low normal or to below normal levels. Methods and pharmaceutical preparations comprising such agents are provided.

Description

RELATED APPLICATIONS[0001]Benefit of priority is claimed under 35 U.S.C. § 119(e) to U.S. Provisional Application Ser. No. 61 / 132,429, filed Jun. 16, 2008, entitled “CONTROLLED RELEASE COMPOSITIONS OF AGENTS THAT REDUCE CIRCULATING LEVELS OF PLATELETS AND METHODS THEREFOR” and U.S. Provisional Application Ser. No. 61 / 209,056, filed Mar. 2, 2009, entitled “CONTROLLED RELEASE COMPOSITIONS OF AGENTS THAT REDUCE CIRCULATING LEVELS OF PLATELETS AND METHODS THEREFOR,” each to Paul F. Glidden, Alison J. Pilgrim and Stephen R. Hanson.; and to United Kingdom Patent Application Serial No. 09 05567.4, filed Mar. 31, 2009, entitled “CONTROLLED RELEASE COMPOSITIONS OF AGENTS THAT REDUCE CIRCULATING LEVELS OF PLATELETS AND METHODS THEREFOR,” filed Mar. 31, 2009.[0002]This application is related International Application No. PCT / US09 / 003,632, filed Jun. 16, 2009, entitled “CONTROLLED RELEASE COMPOSITIONS OF AGENTS THAT REDUCE CIRCULATING LEVELS OF PLATELETS AND METHODS THEREFOR,” which also claims...

AI Technical Summary

Benefits of technology

[0062]Also provided are methods of reducing circulating platelet number in a subject. The methods include administering to the subject any of the controlled release compositions including a platelet number reducing agent described herein. In some embodiments, the composition delivers an amount of the platelet number reducing agent effective to reduce circulating platelet count in the subject by at least 10% of pre-treatment levels. In some embodiments, an elevated circulating platelet count is reduced to at least a normal level. In some embodiments, the circulating platelet count is reduced to at least a low normal level. In some embodiments, the subject has a normal platelet count prior to treatment. In some embodiments, the subject has an above normal platelet count prior to treatment. In the methods provided herein, the platelet number reducing agent is released in an amount and at a rate that reduces adverse events associated with immediate release formulations of the platelet reducing agent. In the methods provided herein, the platelet number reducing agent is released in an amount and at a rate that reduces circulating platelet number in a subject without overtly causing clinical symptoms that prevent or limit therapeutic use of the platelet number reducing agent. In embodiments where the platelet number reducing agent is anagrelide, 3-OH anagrelide or a metabolite or derivative or analog thereof, the agent is released at a rate and in an amount that reduces circulating platelet number in a subject without inhibiting or minimally inhibiting phosphodiesterase (PDE), such as PDE III and PDE V or combinations thereof, so as to reduce the adverse event profile of the platelet number reducing agent.

[0063]Also provided are methods of treating or preventing a thrombotic or thrombo-embolic event or to inhibit a vaso-occlusive event in a subject. The methods include administering to a subject in need of such treatment any of the controlled release compositions of platelet number reducing agent described herein, where the composition delivers an amount of the platelet number reducing agent effective to reduce circulating platelet count in the subject by at least 10% of pre-treatment levels. In some embodiments, an elevated circulating platelet count is reduced to at least a normal level. In some embodiments, the circulating platelet count is reduced to at least a low normal level. In some embodiments, the subject has a normal platelet count prior to treatment. In some embodiments, the subject has an above normal platelet count prior to treatment.

Problems solved by technology

Conditions resulting from thrombotic or thromboembolic events are leading causes of illness and death in adults in western civilization.

Notwithstanding the effort and financial resources that have been invested, these conditions still account for the vast majority of illness and death in the adult populations of developed nations.

The adverse events associated with administration of some platelet number reducing agents, such as anagrelide hydrochloride monohydrate, often lead to discontinuation of the drug as a therapeutic.

The apparently healthy subjects however can still demonstrate particular risk factors which can place them at an elevated risk of a thrombotic event.

In other cases, it is an increase in platelet consumption, elimination or death.

As used herein, “intermittent claudication” refers to a narrowing of the arteries that supply blood to the legs, resulting in a limited supply of oxygen to the leg muscles.

A deleterious interaction also can include degradation of active agent due to or accelerated by interaction with another compound or composition, such as a degradation of active agent during accelerated stability testing catalyzed by or accelerated by interaction with a component of the formulation, such as a plasticizer.

In some instances, the hemihydrate is not as stable as a hydrated crystalline form.

When the platelet count is low, bleeding and / or bruising readily occurs.

In very large numbers—exceeding 600,000 platelets per microliter of blood—platelets can cause clotting in blood vessels and abnormal bleeding.

Conditions resulting from thrombotic or thromboembolic events are the leading causes of illness and death in adults in western civilization.

For example, atherothrombosis, in which acute thrombosis occurs in regions of the vasculature already damaged by atheroma so precipitating stroke, myocardial infarction or limb ischemia, is a major cause of death and disability in the developed world.

Thrombotic events, including thromboembolic events, can be serious medical conditions particularly since they can cause a reduction in blood flow to critical organs including the brain and myocardium.

Coronary thrombosis is the development of an obstructive thrombus in a coronary artery, often causing sudden death or a myocardial infarction.

Subjects who are hypertensive (i.e., those that have high blood pressure) are also at risk of a thrombotic event.

It occurs when the body does not have enough insulin or cannot effectively use insulin to metabolize glucose.

Subjects with cardiovascular disease, cerebrovascular disease and / or peripheral vascular disease (e.g., diabetic feet, failed grafts) are also considered at abnormally high risk of a thrombotic event.

Such procedures can be therapeutic or diagnostic in nature, and thus can also be elective or emergency treatments, and most likely involve the risk of formation of thrombi or the release of emboli.

In addition to the risk of thrombus formation during or immediately following the surgical procedure, there also exists a risk to subjects who have undergone a surgical procedure and are currently immobilized following the procedure.

Thromboembolic events are a major cause of death in this patient group.

There is evidence that a strict control of the platelet count decreases the incidence of thromboembolic complications.

Subjects with thrombocythemia can be afflicted with the condition for several years, and although the condition does not appear to affect life expectancy, vascular complications, including arterial and venous thrombosis, can result in the death of the subject.

IFN-α is a more recent therapeutic agent for the treatment of ET but it is expensive, must be administered as an injectable drug and its acute side effects (e.g., fatigue, depression, influenza-like symptoms, elevated liver enzymes, anorexia, alopecia, neuropsychiatric symptoms) lead to its discontinuation in a significant number of patients (Samuelsson et al., Cancer 106(11): 2397-2405 (2006) and Fruchtman, Leuk Res. 29: 481-491 (2005)).

Production of abnormal cells may replace normal cell production, and a progressive fibrosis or scarring of the bone marrow occurs, reducing its ability to produce blood cells.

In compensation, blood cells are produced in other organs, such as the spleen and the liver, which are not as efficient as blood marrow in producing blood cells.

It has been demonstrated that the risk of atherothrombotic events tends to increase as platelet count increases.

Even when the major mechanisms involved in platelet aggregation are addressed using combination therapy with aspirin (to inhibit thromboxane A2 production and to inhibit the cyclooxygenase pathway) and clopidogrel (to inhibit adenosine diphosphate-induced platelet aggregation pathways and to block the P2Y12 receptor) the reduction in cardiovascular events is only of the order of 25-30% and there is an associated increase in bleeding that can be serious and even life-threatening.

There is evidence that anagrelide also interferes with the activation of the thrombopoietin (TPO) receptor (Petrides, Semin Thromb Hemost.

For some platelet reducing agents in a hydrated crystal form, loss of the water of crystallization can result in loss of activity or decomposition of the agent.

For example, loss of the water of crystallization during mishandling or storage of anagrelide can result in hydrolysis of the lactam ring of anagrelide.

The hydrolysis of the lactam ring of anagrelide presents a long-term stability problem for conventional anagrelide pharmaceutical formulations (e.g., see U.S. Pat. No. 6,388,073).

The compositions provided herein also result in an increased apparent half life of the drug.

Selection of larger solid cores can result in a lower surface area for presentation of the platelet number reducing agent to biological fluids, resulting in slower dissolution rates.

For example, Cmax can be decreased by increasing the size of the microparticles of the platelet number reducing agent, making the agent less easily soluble.

Such hydrophobic interactions between the active ingredient and a fatty acid can result in a fatty acid / active ingredient complex that negatively impacts on the release profile of the active ingredient from the resulting controlled release composition.

One possible adverse side effect can be an inability to clot due to a severe reduction in platelets.

Factors that lower blood volume, renal perfusion pressure, or the concentration of Na+ in plasma tend to activate the system, while factors that increase these parameters tend to suppress its function.

Alkylating agents are compounds that cross-link or cleave DNA, inhibiting replication or causing irreparable modification, resulting in apoptosis.

The isothermal calorimetry data did not suggest a viable alternate to TEC.

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