Sensitive method for the simultaneous measurement of fluphenazine decanoate and fluphenazine in plasma by high-performance liquid chromatography with coulometric detection

Microneedle array patches for sustained delivery of fluphenazine: A micron scale approach for the management of schizophrenia

Schizophrenia is a severe chronic mental illness characterised by impaired emotional and cognitive functioning. To treat this condition, antipsychotics are available in limited dosage forms, mainly oral and injectable formulations. Although injectable antipsychotics were designed to enhance adherence, they are invasive, painful and require a healthcare professional to be administered. To overcome such administration issues, extensive research has been focused on developing transdermal antipsychotic formulations. In this work, three microneedle (MN) systems were developed to deliver fluphenazine (FLU) systemically. A decanoic prodrug of FLU called fluphenazine decanoate (FLUD) was used in two of the MN formulations due to its high lipophilicity. FLU-D was loaded into dissolving MNs and nanoemulsion (NE)-loaded MNs. The parent drug FLU was loaded into poly(lactic-co-glycolic acid) (PLGA)-tipped MNs. All MN systems were characterised and evaluated in vitro and in vivo. The in vivo evaluation of the three developed MN systems showed their ability to deliver FLU into the systemic circulation, as the Cmax of FLU-D dissolving MNs was 36.11 ± 12.37 ng/ml. However, the Cmax of FLU-D NE loaded dissolving MNs was 12.92 ± 6.3 ng/ml and for FLU-PLGA tipped MNs was 21.57 ± 2.45 ng/ml. Compared to an intramuscular (IM) injection of FLU-D in sesame oil, the relative bioavailabilities were 26.96 %, 21.73 % and 42.45 % for FLU-D dissolving MNs, FLU-D NE dissolving MNs and FLU-PLGA tipped MNs, respectively. FLU plasma levels were maintained above the minimum human therapeutic limits for a week. Consequently, these various MN formulations are considered to be a viable options for the transdermal delivery of fluphenazine and its prodrug. The three MN systems developed offer patients a user-friendly, painless, and convenient long-acting delivery method for FLU. Reducing dosing frequency and using less invasive drug administration methods can enhance adherence and foster positive therapeutic outcomes. This study demonstrates the capability and adaptability of MNs technology to transport hydrophobic molecules from the skin to the systemic circulation.

Bioconversion and P-gp-Mediated Transport of Depot Fluphenazine Prodrugs after Intramuscular Injection

Fluphenazine (FPZ) decanoate, an ester-type prodrug formulated as a long-acting injection (LAI), is used in the treatment of schizophrenia. FPZ enanthate was also developed as an LAI formulation, but is no longer in use clinically because of the short elimination half-life of FPZ, the parent drug, after intramuscular injection. In the present study, the hydrolysis of FPZ prodrugs was evaluated in human plasma and liver to clarify the reason for this difference in elimination half-lives. FPZ prodrugs were hydrolyzed in human plasma and liver microsomes. The rate of hydrolysis of FPZ enanthate in human plasma and liver microsomes was 15-fold and 6-fold, respectively, faster than that of FPZ decanoate. Butyrylcholinesterase (BChE) and human serum albumin (HSA) present in human plasma, and two carboxylesterase (CES) isozymes, hCE1 and hCE2, expressed in ubiquitous organs including liver, were mainly responsible for the hydrolysis of FPZ prodrugs. FPZ prodrugs may not be bioconverted in human skeletal muscle at the injection site because of lack of expression of BChE and CESs in muscle. Interestingly, although FPZ was a poor substrate for human P-glycoprotein, FPZ caproate was a good substrate. In conclusion, it is suggested that the shorter elimination half-life of FPZ following administration of FPZ enanthate compared with FPZ decanoate can be attributed to the more rapid hydrolysis of FPZ enanthate by BChE, HSA and CESs.

Forced Degradation Behaviour of Fluphenazine Hydrochloride by LC and Characterization of its Oxidative Degradation Product by LC-MS/MS

A novel, stability-indicating high-performance liquid chromatographic (HPLC) method is delivered for the determination of fluphenazine hydrochloride (FPZ) and its degradation products. The forced degradation testing of FPZ was carried out for hydrolytic, oxidative, photolytic, and thermal degradation. The degradation appeared using a reversed-phase C18 column at ambient temperature with a mobile phase comprised of methanol : acetonitrile : (10 mM) ammonium acetate (70:15:15, v/v/v) pH 6.0, adjusted with acetic acid, having a flow rate of 1 ml min(-1) and a detection wavelength at 259 nm. Primarily, the maximum degradation products were formed under oxidative stress conditions. The product was distinguished through LC-MS/MS fragmentation studies. Based on the results, a more complete degradation pathway for the drug could be proposed. The modernized method was found to be precise, accurate, specific, and selective. The method was found to be suitable for the quality control of fluphenazine hydrochloride in the tablet as well as in stability-indicating studies.

Second-derivative synchronous fluorescence spectroscopy for the simultaneous determination of fluphenazine hydrochloride and nortriptyline hydrochloride in pharmaceutical preparations

A rapid, simple, and highly sensitive second-derivative synchronous fluorimetric (SDSF) method has been developed for the simultaneous analysis of binary mixtures of fluphenazine hydrochloride (FLZ) and nortriptyline hydrochloride (NTP) in their co-formulated tablets. The method is based upon measurement of the native fluorescence of these drugs at constant wavelength difference (Deltalambda) = 120 nm in acetic acid. The different experimental parameters affecting the fluorescence intensity of the studied drugs were carefully studied and optimized. The fluorescence-concentration plots were rectilinear over the range of 0.25-3.0 and 1-10 microg/ml for FLZ and NTP respectively, with lower detection limits (LOD) of 0.05 and 0.18 microg/ml and quantitation limits of 0.15 and 0.53 microg/ml for FLZ and NTP respectively. The proposed method was successfully applied for the determination of the studied compounds in their synthetic mixtures and in commercial co-formulated tablets. The results obtained were in good agreement with those obtained by the reference methods.

Adverse extrapyramidal effects in four horse given fluphenazine decanoate

CASE DESCRIPTION

4 racehorses were examined because of markedly abnormal behavior following administration of fluphenazine decanoate.

CLINICAL FINDINGS

Clinical signs included restlessness, agitation, profuse sweating, hypermetria, aimless circling, intense pawing and striking with the thoracic limbs, and rhythmic swinging of the head and neck alternating with episodes of severe stupor. Fluphenazine was detected in serum or plasma from all 4 horses. The dose of fluphenazine decanoate administered to 3 of the 4 horses was within the range (25 to 50 mg) routinely administered to adult humans.

TREATMENT AND OUTCOME

In 2 horses, there was no response to IV administration of diphenhydramine hydrochloride, but the abnormal behavior in these 2 horses appeared to resolve following administration of benztropine mesylate, and both horses returned to racing. The other 2 horses responded to diphenhydramine administration. One returned to racing. The other was euthanized because of severe neurologic signs, respiratory failure, and acute renal failure.

CLINICAL RELEVANCE

Findings indicate that adverse extrapyramidal effects may occur in horses given fluphenazine decanoate. These effects appear to be unpredictable and may be severe and life threatening. Use of fluphenazine decanoate as an anxiolytic in performance horses is not permitted in many racing and horse show jurisdictions, and analytic procedures are now available to detect the presence of fluphenazine in serum or plasma.

Analysis of certain tranquilizers in biological fluids

A review with 282 references is presented that deals with the reported methods of analysis of phenothiazines, thioxanthenes, and benzodiazepine derivatives of pharmaceutical interest. The review includes the methods adapted in biological fluids.

Fluphenazine plasma level monitoring for patients receiving fluphenazine decanoate

BACKGROUND

Finding a dose of an antipsychotic for maintenance therapy that is both safe and effective can be difficult because clinicians are unable to titrate dose against clinical response in patients who are already stable. Therapeutic monitoring of antipsychotic plasma levels has the potential for helping clinicians in dosage selection. With this in mind, we evaluated the usefulness of monitoring fluphenazine plasma levels for patients with schizophrenia who were receiving maintenance treatment with fluphenazine decanoate.

METHOD

Thirty-one patients with schizophrenia were randomly assigned to low, medium, or high (0.1-0.3, 0.3-0.6, 0.6-1.0 ng/ml) plasma levels of fluphenazine. The dose of fluphenazine decanoate was adjusted in order to maintain patients in their assigned range. Side effects, psychopathology, and psychotic exacerbations were measured during the year following randomization.

RESULTS

All of the psychotic exacerbations occurred during the first eight weeks following randomization, before patients had adequate time to reach their plasma level assignments. We did not find a relationship between plasma levels of fluphenazine and clinical outcomes or side effects.

CONCLUSION

Our results do not provide support for the usefulness of monitoring fluphenazine plasma levels for patients receiving fluphenazine decanoate.

Actions of butyrophenones and other antipsychotic agents at NMDA receptors: relationship with clinical effects and structural considerations

Haloperidol inhibits NMDA receptors with higher affinity for NMDA receptors composed of NR1/2B compared with NR1/2A. To assess whether the clinical effects of haloperidol and other antipsychotic agents are mediated through this site on NMDA receptors and to examine structure activity relationships at this site, we examined the ability of a variety of drugs with neuroleptic actions to inhibit NMDA receptor function. Many antipsychotic agents inhibit 125I-MK 801 binding to the NMDA receptor with IC50 values in the micromolar range. The rank order of potency for inhibition of binding to adult rat forebrain was trifluperidol (TFP) > clozapine = fluphenazine = reduced haloperidol = spiperone = trifluoperazine = butaclamol >> pimozide = risperidone = sulpiride. These findings match the molecular biological specificity of the agents, with trifluperidol having a marked preference for NR1/2B (epsilon2) receptors. Mutations at epsilon2E201, which alter the effects of haloperidol, also decrease the affinity of TFP but not other modulators, showing that the effect of TFP but not other modulators is mediated by this residue of the NMDA receptor. The present results demonstrate that while TFP acts on NMDA receptors in a manner similar to haloperidol, other antipsychotic agents do not share the specific pharmacological properties of this action, suggesting that their clinical mechanism is not mediated by this receptor.

High performance liquid chromatography/electrospray tandem mass spectrometry for phenothiazines with heavy side chains in whole blood

Eleven phenothiazine derivatives with heavy side chains contained in human whole blood have been analyzed by high-performance liquid chromatography (HPLC)/electrospray (ES) tandem mass spectrometry (MS). All compounds gave the base peaks due to [M + 1](+) by HPLC/ES single MS. The product ions formed from each quasi-molecular ion by HPLC/ES tandem MS showed the base peaks due to side chains liberated. The mass chromatography of HPLC/ES tandem MS showed much higher sensitivity than that of HPLC/ES single MS for phenothiazines spiked to whole blood. Therefore, regression equations, detection limits, recovery rates and reproducibility were studied for thiethylperazine, clospirazine and flupentixol spiked to human whole blood by means of mass chromatography of HPLC/ES tandem MS. The three compounds showed good linearity in the range of 2-40 ng/mL with a detection limit of about 0.5 ng/mL. Recoveries of the three compounds spiked to whole blood (2 and 8 ng added to 1 mL whole blood) were 43.4-72.5 %; the coefficients of intraday and interday variations were 3.7-9.3 and 12.6-17.9 %, respectively. Thiethylperazine, clospirazine and flupentixol in whole blood could actually be determined with sufficient sensitivity 3 and 6 h after oral administration of 5-10 mg of each compound in a volunteer.

Studies on the mechanism of absorption of depot neuroleptics: fluphenazine decanoate in sesame oil

PURPOSE

The purpose of the present study was to investigate the pharmacokinetic characteristics of fluphenazine (FLU) and its decanoate (FLU-D) after intravenous and intramuscular administration to dogs.

METHODS

A group of four beagle dogs was used in all intravenous and intramuscular experiments, with washout periods of no less than three months between doses.

RESULTS

After intravenous FLU-D, the pharmacokinetics of the prodrug (mean +/- SD) were as follows: Clearance (CL) 42.9 +/- 6.3 L/h; terminal half-life (t1/2) 3.5 +/- 0.8 h; volume of distribution (Vd) 216 +/- 61 L. The fractional availability of FLU was 1.0 +/- 0.2. After intravenous FLU, the volume of distribution of FLU (51 +/- 17.8 L) was some 4 fold less than that of the prodrug. Simulations (Stella II) suggested that the rate limiting step was slow formation of FLU from the prodrug in the tissue compartment. After intramuscular FLU-D in sesame oil, the apparent t1/2 of FLU was 9.7 +/- 2.0 days whereas after intramuscular FLU base in sesame oil, the apparent t1/2 was only 7.7 +/- 3.4 h showing that the absorption of FLU itself from the intramuscular site and proximal lymph nodes is relatively rapid.

CONCLUSIONS

The rate limiting step after intramuscular FLU-D appeared to be the slow partitioning of the prodrug out of the sesame oil at the injection site and in proximal lymph nodes.