Patent Description:
This disclosure relates to methods of treating psychosis or other psychiatric disorders with extended release paliperidone palmitate injectable suspension.

Paliperidone palmitate is used for the treatment of schizophrenia alone or used in schizoaffective disorders as an adjunctive therapy to antidepressants. It is presently available in an extended release oral tablet (INVEGA® by Jansen Pharmaceuticals) or long acting extended release aqueous injectable suspension suitable for intramuscular (IM) administration (INVEGA SUSTENNA® by Jansen Pharmaceuticals). The intramuscular product has been approved and marketed in the U. since <NUM>.

Paliperidone palmitate undergoes hydrolysis to yield paliperidone, the major active metabolite of risperidone. The injectable formulation is for intramuscular use and has been clinically demonstrated to be safe, well tolerated and with a high efficacy. Its prolonged release and duration of action are attributed to its slow dissolution rate and subsequent hydrolysis to paliperidone.

Given its unique dissolution profile, current paliperidone palmitate therapy requires that two initial loading doses be given one week apart, followed by regular monthly maintenance doses. See, e.g., <CIT>. In particular, INVEGA SUSTENNA® has five strengths at, in descending order, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> of paliperidone palmitate, which are equivalents of <NUM>, <NUM>, <NUM>, <NUM> and <NUM> of paliperidone, respectively. According to its label, INVEGA SUSTENNA® is intended to be administered at its highest strength of <NUM> (i.e., <NUM> paliperidone) on day <NUM> followed by a second loading dose of <NUM> (i.e., <NUM> paliperidone) on day <NUM>. Thereafter, a monthly maintenance dose of <NUM> (i.e., <NUM> paliperidone) is recommended. It is believed that after the initial two loading doses, serum concentration of the active metabolite can rapidly reach therapeutic level and approach the steady-state concentration, which can be further maintained by subsequent monthly maintenance doses. The maintenance dosages may vary from <NUM> to <NUM> (i.e., <NUM>-<NUM> paliperidone) per month depending on tolerability and efficacy with respect to the individual patient. The standard INVEGA SUSTENNA® regimens are referred to herein as "RLD regimens.

Paliperidone palmitate therapy such as INVEGA SUSTENNA® requires two loading doses one week apart in order to rapidly attain therapeutic plasma concentrations. Despite being long-acting in the maintenance period, current therapy compels patient compliance at the initial dosing stage when the patient is the least capable. There exists a need in the art for improved dosage regimen in administering long-acting paliperidone palmitate injectable suspension.

<NPL>) discloses on the cover page (<NUM>/<NUM>) the use of paliperidone palmitate as an extended-release suspension formulation for use in the treatment of schizophrenia or schizoaffective disorders (as monotherapy or as an adjunct to mood stabilizers and antidepressants) wherein the regimen is based on once-monthly administration and follows a specific regimen.

<NPL>) discloses the use of paliperidone palmitate in a suspension for injection, containing varying amounts of paliperidone tailored for the acute and maintenance treatment of schizophrenia in adults. The document also provides details on dosage and methods of administration.

<CIT> provides a method of treating patients in need of treatment with long -acting injectable paliperidone palmitate formulations.

<CIT>provides a method for treating patients in need of psychiatric treatment, wherein said patient is being treated with the <NUM>-month formulation of paliperidone palmitate and fails to take the next scheduled dose of the <NUM>-month formulation of paliperidone palmitate.

<CIT> relates to paliperidone palmitate particles, a process to manufacture the same and pharmaceutical compositions thereof. It further relates to the use of such pharmaceutical compositions in the treatment of schizophrenia, schizoaffective disorder and other related disorders.

<CIT>provides a method of treating patients in need of treatment with long-acting injectable paliperidone palmitate formulations.

The general review of <NPL>) does not provide any specific information concerning the formulations.

Various embodiments provide dosing regimens having alternative initial loading doses, which dosing regimens address the drawbacks of the currently available therapy such as INVEGA SUSTENNA® while achieving a comparable level of systemic exposure during and following the initial dosing phrase. The represent disclosure demonstrates by pharmacokinetic results that it is feasible to achieve comparable systemic exposure by alternative dosing regimens. As such, some of the initial dosing regimens may be able to improve the patient convenience and, hence, increase compliance.

One embodiment provides a dosing regimen having a single, heightened initial loading dose followed by monthly maintenance doses. This simplified dosing regimen obviates two loading doses at the initial dosing stage, thereby enhancing patient compliance without compromising therapeutic effect. More specifically, it is provided paliperidone palmitate for use in a patient in need of treatment of schizophrenia or schizoaffective disorders, the dosing regimen comprising:.

wherein paliperidone palmitate is formulated in an aqueous suspension formulation.

In more specific embodiments, the first loading dose of paliperidone palmitate corresponds to <NUM> of paliperidone.

In a preferred embodiment, the first monthly maintenance dose is in the range of paliperidone palmitate corresponding to <NUM> -<NUM> of paliperidone, or more preferably, a dose of paliperidone palmitate corresponding to <NUM> of paliperidone. Thereafter, the maintenance doses may be in the range of doses of paliperidone palmitate corresponding to <NUM>-<NUM> paliperidone, depending on tolerability and efficacy of the therapy for individual patient.

A further embodiment describes paliperidone palmitate for use in a patient in need of treatment of schizophrenia or schizoaffective disorders, the dosing regimen comprising:.

In more specific embodiments, the first loading dose comprises paliperidone palmitate corresponding to <NUM> of paliperidone.

In a preferred embodiment, the second loading dose is paliperidone palmitate corresponding to <NUM> of paliperidone. In other embodiments, the first monthly maintenance dose is <NUM>. Thereafter, the maintenance doses may be in the range of paliperidone palmitate corresponding to <NUM>-<NUM> (e.g., <NUM>) paliperidone, depending on tolerability and efficacy of individual patient.

The active ingredient of the intramuscular (IM) injectable suspension is paliperidone palmitate. Paliperidone palmitate is the palmitate ester of paliperidone, the major active metabolite of risperidone. The chemical name is (9RS)-<NUM>-[<NUM>-[<NUM>-(<NUM>-Fluoro-<NUM>,<NUM>-benzisoxazol-<NUM>-yl) piperidin-<NUM>-yl]ethyl]-<NUM>-methyl-<NUM>-oxo-<NUM>,<NUM>,<NUM>,<NUM>-tetrahydro-<NUM>-pyrido[<NUM>,<NUM>-a]pyrimadin-<NUM>-yl hexadecanoate. The manufacturing process of paliperidone palmitate comprises a single synthetic step of esterification of paliperidone with palmitic acid, followed by a sterilization process.

Paliperidone palmitate is practically insoluble in aqueous media over a broad pH range. This low solubility allows the drug substance to be formulated as an aqueous suspension for IM injection, which provides an extended release profile that is a function of drug substance particle size.

Paliperidone palmitate can be micronized to desired sizes, which are generally less than <NUM> microns, or more typically less than <NUM> microns, including submicron ranges (i.e., nanometer ranges). The particle sizes can impact the dissolution of paliperidone palmitate, which in turn can impact the release rate of the active metabolite. Typically, larger particles are slower to dissolve and therefore slower to release the active metabolite. Micronization of paliperidone palmitate can be carried out by methods known in the art, including those disclosed in <CIT>.

The paliperidone palmitate particle sizes can be characterized by size distribution within a sample. In certain embodiments, <NUM>% of the particles are less than <NUM> in diameters (e.g., d(<NUM>) is <NUM>). In other embodiments, <NUM>% of the particles are less than <NUM> (e.g., d(<NUM>) is <NUM>). In other embodiments, <NUM>% of the particles are less than <NUM> (e.g., d(<NUM>) is <NUM>). In certain embodiments, the mass median diameter (d(<NUM>)), i.e., the size where <NUM>% of the particles are above and <NUM>% of the particles are below, is in the range of <NUM>-<NUM>. In further embodiments, the mass median diameter is in the range of <NUM> - <NUM>. In further embodiments, the mass median diameter is about <NUM> - <NUM>.

Particle sizes of paliperidone palmitate may also be characterized by specific surface area (SSA). As used herein, the particle sizes of paliperidone palmitate may be in the range of <NUM>-<NUM><NUM>/g. In certain embodiments, the particle sizes are in the range of <NUM>-<NUM><NUM>/g. In other embodiments, the particle sizes are in the range of <NUM>-<NUM><NUM>/g, or in the range of <NUM>-<NUM><NUM>/g, or in the range of <NUM>-<NUM><NUM>/g, or in the range of <NUM>-<NUM><NUM>/g.

Paliperidone palmitate can be formulated as a suspension in any pharmaceutically acceptable diluent including, for example, water. The suspension may further include one or more additives such as buffer, isotonizing agent, preservatives, surfactants, wetting agents suspending agents, and the like.

Suitable suspending agents for use in the aqueous suspensions according to the present invention are cellulose derivatives, e.g. methyl cellulose, sodium carboxymethyl cellulose and hydroxypropyl methyl cellulose, polyvinylpyrrolidone, alginates, chitosan, dextrans, gelatin, polyethylene glycols, polyoxyethylene- and polyoxypropylene ethers. Preferably sodium carboxymethyl cellulose is used in a concentration of <NUM> to <NUM>%, most preferably <NUM>% (w/v).

Suitable wetting agents for use in the aqueous suspensions according to the present invention are polyoxyethylene derivatives of sorbitan esters, e.g. polysorbate <NUM> and polysorbate <NUM>, lecithin, polyoxyethylene- and polyoxypropylene ethers, sodium deoxycholate. Preferably polysorbate <NUM> is used in a concentration of <NUM> to <NUM>%, more preferably <NUM> to <NUM>%, most preferably <NUM>% (w/v).

Suitable buffering agents are salt of weak acids and should be used in amount sufficient to render the dispersion neutral to very slightly basic (pH is <NUM> - <NUM>), preferably in the pH range of <NUM> to <NUM>. Particularly preferred is the use of a mixture of disodium hydrogen phosphate (anhydrous) (typically about <NUM>% (w/v)) and sodium dihydrogen phosphate monohydrate (typically about <NUM>% (w/v)). This buffer also renders the dispersion isotonic and, in addition, less prone to flocculation of the ester suspended therein.

Preservatives are antimicrobials and anti-oxidants which can be selected from the group consisting of benzoic acid, benzyl alcohol, butylated hydroxyanisole, butylated hydroxytoluene, chlorbutol, a gallate, a hydroxybenzoate, EDTA, phenol, chlorocresol, metacresol, benzethonium chloride, myristyl-gamma-piccolinium chloride, phenylmercuric acetate and thimerosal. In particular, it is benzyl alcohol which can be used in a concentration up to <NUM>% (w/v), preferably up to <NUM>% (w/v).

Isotonizing agents are, for example, sodium chloride, dextrose, mannitol, sorbitol, lactose, sodium sulfate. The suspensions conveniently comprise from <NUM> to <NUM>% (w/v) isotonizing agent. Mannitol may be used in a concentration from <NUM> to <NUM>% More preferably, however, from about <NUM> to about <NUM>% (w/v), especially from about <NUM> to about <NUM>% (w/v) of one or more electrolytes are used to render the suspension isotonic, apparently because ions help to prevent flocculation of the suspended ester. In particular, electrolytes of the buffer serve as isotonizing agent.

Additional detailed description of the preparation of paliperidone palmitate suspension may be found in <CIT>,<CIT>.

In various embodiments, the aqueous suspension formulations may comprise, by the weight percentage based on the total weight of the formulation: (a) from <NUM> to <NUM>% (w/w) of paliperidone palmitate; (b) from <NUM> to <NUM>% (w/w) of a wetting agent; (c) one or more buffering agents sufficient to render the composition neutral to very slightly basic (pH <NUM>); (d) from <NUM> to <NUM>% (w/w) of a suspending agent; (e) up to <NUM>% (w/w) preservatives; and (f) water q. Preferably the aqueous suspension will be made under sterile conditions and no preservatives will be used.

In preferred embodiments, the aqueous suspension formulation is an aqueous suspension of particulate paliperidone palmitate having the size distribution as disclosed herein. Suitable additives include polysorbate <NUM>, polyethylene glycol <NUM>, citric acid monohydrate, disodium hydrogen phosphate anhydrous, sodium dihydrogen phosphate monohydrate, sodium hydroxide. The amount of paliperidone palmitate in the aqueous suspension formulation may be: <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM>, which correspond to <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> of paliperidone, respectively. In various embodiments, the concentration of paliperidone palmitate in aqueous suspension formulation is about 15w/w%.

Based on the collective comparable in vitro dissolution data, the preclinical animal PK data and the preliminary pharmacokinetic (PK) modeling and simulation using available human PK data of INVEGA SUSTENNA®, provided herein are alternative dosing regimens having simplified initial dosing phases while achieving a superior or comparable level of systemic exposure of paliperidone to that of the initial dosing regimen of INVEGA SUSTENNA®. Advantageously, the dosing regimens are capable of enhancing patient compliance, especially during the initial dosing phase when patient compliance is critical in achieving adequate efficacy that may induce future compliance during the maintenance period.

Thus, one embodiment provides a dosing regimen having a single, heightened initial loading dose followed by monthly maintenance doses. This simplified dosing regimen obviates two loading doses at the initial dosing stage, thereby enhancing patient compliance without compromising therapeutic effect. More specifically, provided is paliperidone palmitate for use in a patient in need of treatment of schizophrenia or schizoaffective disorders, the dosing regimen comprising:.

In a preferred embodiment, the first loading dose of paliperidone palmitate corresponds to <NUM>-<NUM> (e.g., <NUM>) paliperidone.

As used herein, a "loading dose" is a heightened dose typically given at the beginning of a course of treatment. The first loading dose is given on the first day (day <NUM>) of the treatment and is at a higher amount than any of the doses given thereafter. Loading dose is typically followed by maintenance doses given at regular intervals, although sometimes a second loading dose may be given after the first loading dose and before the maintenance doses.

As used herein, "monthly maintenance dose" refers to regularly administered injection within about four weeks (<NUM> days ± <NUM> days) from the immediate preceding dose. The immediate preceding dose may be the initial loading dose. Thus, according to this embodiment, the first monthly maintenance dose begins on the 29th day (or within a window of ± <NUM> days thereof) from the initial loading dose on day <NUM>. The second monthly maintenance dose begins on the 29th day (within a window of ± <NUM> days thereof) from the immediate preceding dose (e.g., the first monthly maintenance dose), and so forth.

During the maintenance period in which regular monthly injections are given, each dosing strength may be the same or different. In a preferred embodiment, the first monthly maintenance dose is in the range of <NUM>-<NUM> paliperidone as paliperidone palmitate, or more specifically, <NUM> of paliperidone as paliperidone palmitate. Thereafter, the one or more further monthly maintenance doses may be in the range of <NUM>-<NUM> paliperidone as paliperidone palmitate, depending on tolerability and efficacy of the therapy on individual patient. Specifically, the monthly maintenance doses may be <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> of paliperidone as paliperidone palmitate. In a preferred embodiment, the further monthly maintenance doses are <NUM> of paliperidone as paliperidone palmitate.

<FIG> shows the preliminary pharmacokinetic modeling and simulation. As shown, a single, heightened loading dose of <NUM> is followed by a maintenance dose in different strengths within <NUM> days (i.e., given on the 29th day from the loading dose administered on the first day). The PK profiles closely track the PK profile of INVEGA SUSTENNA® dosing regimen according to its label (i.e., the "RLD" regimen), indicating that a sufficiently high therapeutic level of the active substance is achieved under the simplified regimen having a single loading dose.

A further embodiment describes yet another dosing regimen by which two initial loading doses are administered about two weeks (<NUM> days) apart, followed by monthly maintenance doses. More specifically, this embodiment provides paliperidone palmitate for use in a patient in need of treatment of schizophrenia or schizoaffective disorders, the dosing regimen comprising:.

In preferred embodiments, the second loading dose is <NUM> paliperidone as paliperidone palmitate. In other embodiments, the first monthly maintenance dose is <NUM> of paliperidone as paliperidone palmitate. Thereafter, the one or more further monthly maintenance doses may be in the range of <NUM>-<NUM> paliperidone as paliperidone palmitate, depending on tolerability and efficacy of the therapy on the individual patient. Specifically, the monthly maintenance doses may be <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> of paliperidone as paliperidone palmitate.

<FIG> demonstrates that, in simulation, the PK profiles according to the above embodiment track closely to that of INVEGA SUSTENNA® (shown as having an initial loading dose of <NUM> on day <NUM>).

<FIG> demonstrates that, in simulation, the PK profiles of longer treatment into the maintenance period according to the dosing regimens disclosed herein also track closely to the conventional therapy, further indicating the efficacy of the improved dosing regimens.

The therapy disclosed herein is suitable for treating or alleviating the symptoms of psychosis and psychiatric disorders in patients for all the known uses of risperidone. These mental disorders include, but are not limited to, schizophrenia; bipolar disorder or other disease states in which psychosis, aggressive behavior, anxiety or depression is evidenced. Schizophrenia refers to conditions characterized as schizophrenia, schizoaffective disorder and schizophreniform disorders, in DSM-IV-TR such as category <NUM>.

The injectable paliperidone palmitate describe herein is developed as a white to off-white sterile aqueous extended-release suspension for intramuscular injection. Table <NUM> shows paliperidone palmitate injectable suspension in various strengths. In addition to the active paliperidone palmitate, other components are listed by their respective weight and w/w percentages. Other strengths, including <NUM>, <NUM>, <NUM> and <NUM> of paliperidone palmitate, can be prepared by proportionally adjusting the various ingredients in the formulations.

Paliperidone palmitate is micronized aseptically using wet milling. The aseptic wet milling process uses a type of milling beads in the mill machine to obtain particles of micronized paliperidone palmitate with desired size distribution. In this process, the sterility of the final product is ensured by using a sterilization filtration and aseptic process. The injectable suspension is provided in a prefilled syringe with a plunger stopper and tip cap. The kit also contains <NUM> safety needles (a 1½-inch <NUM> gauge safety needle and a <NUM>-inch <NUM> gauge safety needle). Table <NUM> shows that the particle size distributions in the paliperidone palmitate injectable suspension are the same or comparable to those of the commercial INVEGA SUSTENNA®.

The in vitro release of the injectable suspension is evaluated by the FDA recommended dissolution method for paliperidone palmitate extended release suspension using USP Type II (paddle) apparatus with <NUM> <NUM> HCl containing <NUM>% Polysorbate <NUM> at temperature <NUM> ± <NUM> at <NUM> rpm. The results showed that the in vitro release profile of Example <NUM> is identical to that of INVEGA SUSTENNA® (<FIG>).

The paliperidone palmitate injectable suspension includes the following strengths: <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> which correspond to <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> of paliperidone, respectively.

A pharmacokinetic study in Beagle dogs indicated that following intramuscular administration, the plasma exposure of <NUM>/kg of the injectable suspension of Example <NUM> (based on the paliperidone palmitate) was comparable to that of <NUM>/kg of INVEGA SUSTENNA®. In support of the rationale for the proposed development program, preclinical studies in beagle dogs were performed. Beagle dogs were randomly divided in two groups (five animals/group/sex). Group <NUM> received single IM injection of Example <NUM> at <NUM>/kg, and Group <NUM> received single IM injection of INVEGA SUSTENNA® at <NUM>/kg. Blood samples (<NUM>) was collected at pre-dose and <NUM>, <NUM>, 1d, 2d, 4d, 7d, 9d, 11d, 14d, 17d, 21d, 24d, 28d, 31d, 35d post dose. Paliperidone was determined by LC-MS/MS method.

The mean plasma concentration-time profiles of paliperidone after a single IM injection of Example <NUM> and INVEGA SUSTENNA® were shown in <FIG>. Summary pharmacokinetic parameters are presented in Table <NUM>.

The relative bioavailability (AUC) of Example <NUM> in dogs was <NUM>% and Cmax was <NUM>%, respectively, when compared to INVEGA SUSTENNA® at an equivalent i. dose of <NUM>/kg.

The simplified dosing regimen according on one embodiment comprises a high loading dose followed by monthly maintenance doses for the drug product of Example <NUM>. The regimen requires one fewer dose initially and allows for a longer interval between the first loading dose and the subsequent maintenance dose, when compared to the standard INVEGA SUSTENNA® dosing regimen (RLD regimen). <FIG> demonstrates the simulated PK profiles of the simplified dosing regimen disclosed herein having a heightened initial loading dose following by monthly maintenance doses compared to the simulated PK profile of the RLD regimen.

The clinical simulations show a faster onset of drug release and less fluctuations in the plasma profiles over the first two months and comparability thereafter. The following table summarizes the analysis including partial AUC breakdowns.

Animal testing was also carried out to analyze the in vivo PK behaviors under the various dosing regimens disclosed herein.

<NUM> healthy male beagle dogs (average weight about <NUM>) were randomly divided into <NUM> groups (Groups I-V) with <NUM> dogs in each group. Each animal was assigned its own number (#<NUM>-#<NUM>).

Group I animals (#<NUM>-#<NUM>) and Group IV animals (#<NUM>-#<NUM>) were tested under RLD regimen. Group II animals (#<NUM>-#<NUM>) were tested under Regimen A. Group III animals (#<NUM>-#<NUM>) and Group V animals (#<NUM>-#<NUM>) were tested under Regimen B. Table <NUM> summarizes the respective human dosages (mg of paliperidone) and the equivalent animal dosages (converted to mg/kg) and the dosing intervals under each dosing regimen.

The animals in each group received intramuscular injections according to the dosing regimen assigned to the group. Blood samples (<NUM>/collection) were collected from the forelimb vein of each beagle immediate before administration (at <NUM>), and thereafter at time intervals of <NUM> (day <NUM>), 24hr (day <NUM>), day <NUM>, day <NUM>, day <NUM> (prior to dosing for groups receiving RLD regimen), day <NUM>, day <NUM>, day <NUM>, day <NUM> (prior to dosing for groups receiving Regimen A), day <NUM>, day <NUM>, day <NUM>, day <NUM>, day <NUM>, day <NUM> (prior to dosing for groups receiving Regimen A), day <NUM>, day <NUM>, day <NUM>, day <NUM> (prior to dosing for groups receiving RLD and Regimen A), day <NUM>, day <NUM>, day <NUM>, day <NUM>, day <NUM>, day <NUM>, day <NUM>, day <NUM>, day <NUM>, day <NUM>, day <NUM>, and day <NUM>. The blood samples were placed in heparinized centrifuge tubes and centrifuged for <NUM> (<NUM> rpm). The plasma was separated, collected and stored under -<NUM>° C.

Plasma concentrations of the samples collected from Group I and Group IV animals are shown in Table <NUM>.

The PK data shown in Table <NUM> are plotted into various PK curves. <FIG> shows the PK curves of plasma concentration data obtained from Group I animals. <FIG> shows the PK curve based on the average plasma concentration data obtained from Group I animals.

<FIG> shows the PK curves based on the plasma concentration data obtained from Group IV animals. Data from one animal (#<NUM>) appeared to deviate from its cohorts. <FIG> shows the respective PK curves based on the average data of Group IV animals with or without taking into consideration of data from #<NUM> animal.

Table <NUM> summarizes the PK parameters derived from the PK curves for Groups I and IV animals. Standard deviation (SD) and coefficient of variation (CV%) are also provided.

Plasma concentrations of the samples collected from Group II animals are shown in Table <NUM>.

The PK data shown in Table <NUM> are plotted into various PK curves. <FIG> shows the PK curves of plasma concentration data obtained from Group II animals. <FIG> shows the PK curve based on the average plasma concentration data obtained from Group II animals.

Table <NUM> summarizes the PK parameters derived from the PK curves for Group II animals. Standard deviation (SD) and coefficient of variation (CV%) are also provided.

Plasma concentrations of the samples collected from Group III and Group V animals are shown in Table <NUM>.

The PK data shown in Table <NUM> are plotted into various PK curves. <FIG> shows the PK curves of Group III animal data. Data from one animal (#<NUM>) appeared to deviate from its cohorts. <FIG> shows the respective PK curves based on the average data of Group III animals (with or without taking into consideration of data from #<NUM> animal).

<FIG> shows the PK curves of Group V animal data. Data from one animal (#<NUM>) appeared to deviate from its cohorts. <FIG> shows the respective PK curves based on the average data of Group V animals (with or without taking into consideration of data from #<NUM> animal).

Table <NUM> summarizes the PK parameters derived from the PK curves for Groups III and V animals. Standard deviation (SD) and coefficient of variation (CV%) are also provided.

Based on the animal studies and the in vivo PK data obtained, the following observations are made with regard to the dosing regimens of the paliperidone palmitate injectable suspension according to the embodiments disclosed herein.

<FIG> shows the average PK curves based on the plasma concentration data obtained from animals of Groups I (standard RLD Regimen), Group II (Regimen A) and Group III (Regimen B). As shown, with the heightened initial dose of <NUM> human equivalent dose of paliperidone as paliperidone palmitate, Regimen B reached Cmax earlier (Tmax ≈<NUM> days) than RLD Regimen (Tmax ≈ <NUM> days) did, even though the latter had a combined first and second loading of <NUM> (human equivalent dose). Under Regimen B, the Cmax was comparable to that of RLD Regimen despite having a heightened loading dose, thus alleviating concerns of adverse effects associated with the plasma concentrations of paliperidone being too high. Furthermore, despite the longer interval between the first and second dose under Regimen B, the trough (day <NUM>) was comparable to the plasma concentration on day <NUM> under RLD Regimen and was indeed higher than the trough under the RLD Regimen (day <NUM>). The overall drug exposures (AUC) are comparable for all three Regimens.

<FIG> shows the average PK curves based on plasma concentration data obtained from animals of Groups IV (RLD Regimen) and Group V (Regimen B). Consistent with the results shown in <FIG>, Regimen B reached Cmax earlier, despite having only a single loading dose that is lower than the combined first and second loading doses of RLD Regimen. Under Regimen B, despite having a heightened initial loading dose, the Cmax was comparable to that of RLD Regimen. In addition, under Regimen B, the trough (day <NUM>) was comparable to the same-day concentration of RLD Regimen and higher than the trough of the RLD Regimen.

Claim 1:
Paliperidone palmitate for use in a patient in need of treatment of schizophrenia or schizoaffective disorders by a dosing regimen comprising :
(<NUM>) administering intramuscularly to the patient a first loading dose of <NUM>-<NUM> of paliperidone palmitate on the first day of treatment; and
(<NUM>) beginning on the 29th day ± <NUM> days from the first loading dose, administering intramuscularly to the patient a first monthly maintenance dose in the range of <NUM>-<NUM> of paliperidone palmitate, wherein each dose of paliperidone palmitate is formulated in an aqueous suspension formulation.