An analytical strategy to characterize the pharmacokinetics and pharmacodynamics of triptorelin in rats based on simultaneous LC–MS/MS analysis of triptorelin and endogenous testosterone in rat plasma

Green hydrophobic maltodextrin nanosponges for magnetic solid-phase extraction of hypothalamic peptides from plasma samples

In this work, for the first time, magnetic-phthalated maltodextrin nanosponges (M-PAMDNSs) were synthetized and introduced as efficient and green sorbents. The integration of phthaloyl groups as hydrophobic moieties into networks of maltodextrin nanosponges provided good enrichment for hypothalamic-related peptides (HRPs). The synthesized materials were characterized by 1H nuclear magnetic resonance spectroscopy, water contact angle, attenuated total reflection-Fourier transform infrared spectroscopy, dynamic light scattering, zeta potential, pH point of zero charge, acid-base titration, field-emission scanning electron microscopy, Brunauer-Emmett-Teller, and vibrating sample magnetometer. Under the optimized conditions (sorbent amount: 5.0 mg, desorption solvent volume and type: 300 µL of methanol: H2O: trifluoroacetic acid, extraction time: 15 min, and desorption time: 10 min), the developed magnetic solid-phase extraction (MSPE) method in combination with HPLC-UV was used as a novel and sensitive analytical method for the determination of HRPs in plasma samples. The proposed MSPE-HPLC-UV method provided good linearity (1.5-500 ng mL-1 R2 ≥ 0.9988), low limits of detection (0.1-0.2 ng mL-1) and quantification (0.4-0.8 ng mL-1), desirable precision (RSD ≤ 8.8%, n ₌ 5), satisfactory enrichment factor (EFs ≥ 66.0), and well relative recoveries (92.8-108.8%). Overall, the established method effectively expanded the analytical potential of MSPE approach for the quantification of HRPs in biological samples.

Silk fibroin double-layer microneedles for the encapsulation and controlled release of triptorelin

A double-layer silk fibroin microneedles (SF-MNs) was proposed for the transdermal delivery of triptorelin. Two-step pouring and centrifugation were employed to prepare SF-MNs. Triptorelin was wrapped in MNs in the form of microcrystals with a size of ∼1 μm. β-sheet nanocrystals (the secondary structure of silk fibroin) were adjusted in content by methanol-vapor treatment to manipulate the characteristics of SF-MNs prepared with two concentrations of silk fibroin. The mechanical strength of MNs was measured and analyzed in proportion to the β-sheet content. The triptorelin in MNs could be released sustainedly in phosphate-buffered saline for 168 h, and the release amount decreased with increasing β-sheet content. The Ritger-Peppas equation was employed to fit the release data. A linear decreasing relationship was observed between the diffusion coefficient and increased β-sheet content. After administration to rats, SF-MNs exhibited long-term testosterone inhibition and maintained castration levels for ≥7 d. Manipulable mechanical properties and release behavior combined with biocompatibility and biodegradability render SF-MNs as viable long-term transdermal delivery devices for triptorelin.

Simultaneous determination of nicotinamide and N1 -methylnicotinamide in human serum by LC-MS/MS to associate their serum concentrations with obesity

A rapid and sensitive LC-MS/MS method was developed and validated for the simultaneous determination of nicotinamide and its metabolite N¹ -methylnicotinamide in human serum. Serum samples were prepared by protein precipitation with acetonitrile. The chromatographic separation was performed on a Waters Spherisorb S5 CN microbore column (2.0 × 100 mm, 5 μm) with gradient elution within 7 min. Acetonitrile and 5 mm ammonium formate aqueous solution (containing 0.1% formic acid) were used as mobile phases. Nicotinamide, N¹ -methylnicotinamide and N'-methylnicotinamide (internal standard) were detected with a triple-quadrupole tandem mass spectrometer in the positive ion mode. Multiple reaction monitoring was used to monitor precursor to product ion transitions of m/z 123.1 → 80.1 for nicotinamide, m/z 137.1 → 94.1 for N¹ -methylnicotinamide and m/z 137.1 → 80.1 for the internal standard. The linear ranges of nicotinamide and N¹ -methylnicotinamide were 5.000-160.0 and 2.500-80.00 ng/ml, respectively. The intra- and inter-day precisions (RSD) of both analytes were within 6.90%. The recoveries were >88%. The analytes were proven to be stable during all sample storage, preparation and analytic procedures. The method was successfully applied to determine the concentrations of nicotinamide and N¹ -methylnicotinamide in human serum to investigate the association between their concentrations and obesity in 1160 Chinese subjects.

Magnetic solid-phase extraction of high molecular weight peptides using stearic acid-functionalized magnetic hydroxyapatite nanocomposite: determination of some hypothalamic agents in biological samples

Therapeutic peptides have an important effect on physiological function and human health, so it is momentous to quantify and detect low levels of these biomolecules in biological samples for treatment and diagnostic purposes. In the present study, an efficient magnetic solid-phase extraction (MSPE) method was developed based on stearic acid-functionalized magnetic hydroxyapatite nanocomposite (MHAP/SA) as a novel and cost-effective adsorbent for extraction of five hypothalamic-related peptides (goserelin, octreotide, triptorelin, somatostatin, and cetrorelix) from biological samples. To characterize the morphology and physicochemical properties of MHAP/SA, Fourier transform infrared spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy (EDS), field emission scanning microscopy (FE-SEM), CHNS elemental analysis, Brunauer-Emmett-Teller (BET), and vibrating sample magnetometry (VSM) were applied. Under optimum conditions, the proposed method (MSPE-HPLC-UV) represented favorable linearity with R² ≥ 0.9987, suitable intra- and inter-day precisions (RSD ≤ 6.9% and RSD ≤ 8.1%, respectively, n = 3), and limits of detection and quantification in the range of 0.75-1.12 ng mL^-1 and 2.50-3.75 ng mL^-1, respectively. Eventually, the proposed method was used for the extraction and quantification of target therapeutic peptides in plasma and urine samples, and satisfactory relative recoveries were achieved in the range of 90.6-110.3%.

Capillary Electrophoresis-Mass Spectrometry with Multisegment Injection and In-Capillary Preconcentration for High-Throughput and Sensitive Determination of Therapeutic Decapeptide Triptorelin in Pharmaceutical and Biological Matrices

A capillary electrophoresis-tandem mass spectrometry method with a multisegment injection and an in-capillary field-enhanced sample stacking for determination of therapeutic peptide triptorelin in pharmaceutical and biological matrices was developed. The CE separation conditions were optimized in order to obtain maximal separation efficiency, analytical signal intensity and stability, and minimal adsorption of the analyzed peptide onto the capillary wall (1 M formic acid-HFo, pH 1.88). The implementation of the field-enhanced sample injection into CE improved the value of limit of detection 50 times while the multisegment injection increased the sample throughput three times in comparison to a conventional CE approach. The proposed method was characterized by favorable performance parameters, such as linearity (r2 ≥ 0.99), limit of detection (5 ng mL-1 in water matrix, 25 ng mL-1 in plasma matrix), precision (relative standard deviation, 1.5-9.4% for intraday and 2.3-11.9% for interday reproducibility), or accuracy (relative errors in the range of 80-109%). The FDA-validated method was successfully applied to the analysis of triptorelin in the commercial drug Diphereline® 0.1 mg (powder for injection) and in spiked human plasma samples. Favorable performance parameters along with proven application potentialities indicate the usefulness of the proposed method for its routine use in drug quality control laboratories and for clinical analysis, such as determination of triptorelin levels in plasma (for pharmacokinetic study).

Pituitary adenoma and apoplexy during GnRH agonist treatment for IVF - case report

In vitro fertilization is commonly used for treating infertility. One stage of this process is controlled hyperstimulation of the ovaries, achieved by administering gonadotropins. There are several stimulation protocols utilized that increase the number of ovarian follicles during IVF. The most common protocol employs desensitization - the inhibition of follicle-stimulating hormone and luteinizing hormone secretion by the pituitary gland. This is achieved by administering a gonadotropin-releasing hormone (GnRH) analog that is agonistic for the GnRH receptor. However the use of a this drug during therapy carries a risk of complications. This case report deals with a rare case of a woman who underwent pituitary tumor growth as a result of the treatment of GnRH analog.

LC-MS/MS assay for the determination of a novel D-peptide antagonist of CXCR4 in rat plasma and its application to a preclinical pharmacokinetic study

DV1 is a potent and selective D-peptide antagonist of CXCR4 and being developed as a novel drug candidate molecule. For preclinical pharmacokinetic study of DV1, we established an efficient and reliable liquid chromatography coupled to tandem mass spectrometric (LC-MS/MS) method for the assay of DV1 in rat plasma. Plasma samples were acidified by formic acid and then their protein content precipitated by acetonitrile. Sample separation was processed with a C18 column (4.6 mm × 100 mm, 5 μm) and washed by a water-acetonitrile gradient mobile phase containing 0.1% (v/v) formic acid at a flow rate of 0.4 mL/min. The mass spectrometer was operated in the multiple reaction monitoring mode and positive electrospray ionization. The assay had a good linearity over the range of 10-10000 ng/mL (r>0.998) for DV1. The adsorption of the peptide was diminished by organic additives during the quantitative procedure. The intra- and inter-day precision was 1.9-9.8% and the accuracy was 91.2-110.0%. No significant variation was observed under the optimized conditions. The recovery was above 52% with low matrix effects. The method was successfully applied to a pharmacokinetic study of DV1 after subcutaneous injection at dose of 10 mg/kg in rats. The half-life and AUC_inf of DV1 were calculated as 8.7 h and 35,553 ng/mL·h, respectively. It is the first report on the quantitative analysis and pharmacokinetic characterization of a D-peptide targeted CXCR4, which should be useful for further preclinical studies and development of this and other peptide therapeutics.

Pharmacokinetic-Pharmacodynamic Model for the Testosterone-Suppressive Effect of Leuprolide in Normal and Prostate Cancer Rats

This study developed the pharmacokinetic (PK)–pharmacodynamic (PD) model of the testosterone-suppressive effect of leuprolide for evaluation of the sustained release (SR) depot and leuprolide solution in rats with or without prostate cancer. Six groups of rats were divided by the routes of administration (intravenous and subcutaneous injection) and kinds of formulation (vehicle, leuprolide solution, and SR depot). The PK profile after subcutaneous injection of leuprolide solution could be well-described by the one-compartment model. The absorption rate constant, the total body clearance, and the volume of distribution were estimated at 16.67 h⁻¹, 514.46 mL/h, and 487.40 mL. Using PK parameters in the solution-administered group, the PK model for the SR depot was developed. The PK–PD model was constructed by describing the testosterone-suppressive effect of leuprolide using the feedback turnover model. The response of testosterone after administration of each formulation was well described using this PK–PD model for the estimation of PD parameters (EC₅₀, E_max, h) and systemic parameters (k_in, k_out, k_{f on}, k_{f off}). The developed PK–PD model containing an inhibitory feedback system could successfully describe the testosterone-suppressive effect of leuprolide in the type of formulation. The PK–PD model developed would be useful for evaluating the formulation of similar drugs whose effect is regulated through the feedback mechanism.

Triptorelin relieves lower urinary tract symptoms in Chinese advanced prostate cancer patients: a multicenter, non-interventional, prospective study

BACKGROUND

Although triptorelin is increasingly used in China for biochemical castration, its effects on primary prostate cancer symptoms remain unclear. This study aimed to assess the prevalence of lower urinary tract symptoms (LUTS) in Chinese prostate cancer patients and the effectiveness of triptorelin on LUTS.

METHODS

In this 48-week multicenter, non-interventional, prospective study, we enrolled patients with locally advanced or metastatic prostate cancer. Patients received triptorelin (15 mg) intramuscularly at baseline and at weeks 12, 24, and 36 with symptom assessment using the International Prostate Symptoms Score (IPSS). The primary endpoints were the prevalence of LUTS at baseline per IPSS categories and the percentage of patients with moderate to severe LUTS (IPSS > 7) at baseline, having at least a 3-point reduction of IPSS score at week 48.

RESULTS

A total of 398 patients were included; 211 (53.0%) and 160 (40.2%) among them had severe and moderate LUTS, respectively. Of the patients with IPSS scores available at baseline and at week 48 (n = 213), 81.2% achieved a reduction in IPSS of at least 3 points. Of the patients with moderate to severe LUTS at baseline and IPSS scores available at baseline and at week 48 (n = 194), 86.6% achieved a total IPSS reduction of at least 3 points.

CONCLUSIONS

The vast majority of Chinese patients with locally advanced or metastatic prostate cancer scheduled to receive triptorelin as part of their standard treatment have severe or moderate LUTS. Triptorelin therapy resulted in sustained improvement of LUTS in these patients.