19F Nuclear Magnetic Resonance Spectrometric Determination of the Partition Coefficients of Flutamide and Nilutamide (Antiprostate Cancer Drugs) in a Lipid Nano-Emulsion and Prediction of Its Encapsulation Efficiency for the Drugs

Lipophilicity Modulations by Fluorination Correlate with Membrane Partitioning

Bioactive compounds generally need to cross membranes to arrive at their site of action. The octanol-water partition coefficient (lipophilicity, logPOW ) has proven to be an excellent proxy for membrane permeability. In modern drug discovery, logPOW and bioactivity are optimized simultaneously, for which fluorination is one of the relevant strategies. The question arises as to which extent the often subtle logP modifications resulting from different aliphatic fluorine-motif introductions also lead to concomitant membrane permeability changes, given the difference in molecular environment between octanol and (anisotropic) membranes. It was found that for a given compound class, there is excellent correlation between logPOW values with the corresponding membrane molar partitioning coefficients (logKp ); a study enabled by novel solid-state 19 F NMR MAS methodology using lipid vesicles. Our results show that the factors that cause modulation of octanol-water partition coefficients similarly affect membrane permeability.

A sonochemical synthesis of SrTiO3 supported N-doped graphene oxide as a highly efficient electrocatalyst for electrochemical reduction of a chemotherapeutic drug

A sonochemical based green synthesis method playa powerful role in nanomaterials and composite development. In this work, we developed a perovskite type of strontium titanate via sonochemical process. SrTiO₃ particles were incorporated with nitrogen doped graphene oxide through simple ultrasonic irradiation method. The SrTiO₃/NGO was characterized by various analytical methods. The nanocomposite of SrTiO₃/NGO was modified with laser-induced graphene electrode (LIGE). The SrTiO₃/NGO/LIGE was applied for electrochemical sensor towards chemotherapeutic drug detection (nilutamide). Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques have been used to examine the electrochemical performance of nilutamide (anti-cancer drug). DPV was found to be more sensitive and found to exhibit a sensitivity 8.627 µA µM^-1 cm^-2 for SrTiO₃/NGO/LIGE with a wide linear range (0.02-892 µM) and low Limit of detection (LOD: 1.16 µM). SrTiO₃/NGO/LIGE has been examined for the detection of nilutamide in blood serum and urine samples and obtained a good recovery in the range of 97.2-99.72 %. The enhanced stability and selectivity and practical application results indicates the suitability of SrTiO₃/NGO/LIGE towards the detection of nilutamide drug in pharmaceutical industries.

Effects of mono- and dialkylglucosides on the characterisation and blood circulation of lipid nanoemulsions

Aim: Effects of two cosurfactants, n-alkylglycosides with mono- or disaccharide groups - N-nonyl β-D-glucopyranoside (N-Glu) and N-decyl β-D-maltoside (D-Mal) - were studied to the stability in saline solution, interaction with serum albumin, and blood circulation of the lipid nanoemulsion (LNE).Methods: The LNEs composed of soybean oil, phosphatidylcholine, and sodium palmitate were prepared without (Control-LNE) and with N-Glu or D-Mal (NG-LNE and DM-LNE, respectively).Results: In saline solution, NG-LNE exhibited a smaller droplet size than Control-LNE, while the size of DM-LNE was significantly increased compared with the other LNEs. The fluorescence resonance energy transfer method showed that the order of albumin interaction was DM-LNE > NG-LNE > Control-LNE. In vivo blood circulation in mice, showed greater fractions of both NG-LNE and DM-LNE remaining in blood over time compared with Control-LNE.Conclusions: The nature of high stability in saline solution and high affinity for serum albumin led to the prolonged circulation of LNE.

Thermal Behavior of 19F Nuclear Magnetic Resonance Signal of 19F-Containing Compound in Lipid Nano-Emulsion for Potential Tumor Diagnosis

We developed carriers of a ¹⁹F magnetic resonance imaging (¹⁹F MRI) agent, capable of responding to the temperature difference for cancer diagnosis. The carriers were based on high melting point (mp) neutral lipids, namely, tripalmitin (TPT) and tristearin (TSR) and triarachidin (TAC). Lipid nano-emulsions (LNEs) containing a fluorine compound, i.e., a modified α-tocopherol (¹⁹F-TP), were respectively prepared as TPT-LNE, TSR-LNE, TAC-LNE1, and TAC-LNE2 and studied by ¹⁹F NMR spectroscopy. In LNE prepared with soybean oil as a control, the full width at half maximum (FWHM) values of the ¹⁹F NMR signal of ¹⁹F-TP remained constant at 25, 37, and 42°C, while those of the LNEs prepared from a neutral lipid with a high mp showed a sharp decrease between 25 and 37°C. The magnitude of the decrease followed the order: TPT-LNE < TSR-LNE < TAC-LNE1. However, TAC-LNE2, for which the amount of encapsulated ¹⁹F-TP was one third less than that of TAC-LNE1, showed a sharp decline in the FWHM between 37 and 42°C. To examine these changes, the ¹⁹F spin-lattice (T₁) and spin-spin (T₂) relaxation times of ¹⁹F-TP were measured. TAC-LNE2 in particular showed a substantial change in its T₂ value between 37 and 42°C compared with the change of its T₁ value. This result was attributed to activation of the molecular motion of ¹⁹F-TP in TAC-LNE2 from 37 to 42°C. Thus, TAC-LNE showed potential for use as a carrier for cancer diagnosis using ¹⁹F MRI.

Application of Ultra-Centrifugation and Bench-Top 19F NMR for Measuring Drug Phase Partitioning for the Ophthalmic Oil-in-Water Emulsion Products

Generic drug products are expected to have the same active pharmaceutical ingredient (API) (Q1) with the same content (Q2) and microstructure arrangement (Q3) as the innovator product. In complex oil-in-water emulsion drugs, the hydrophobic API is mainly formulated in oil droplets stabilized by surfactant and micelles composed of extra surfactant molecules. The API phase partition in oil and water (mainly micelle) is a critical quality attribute (CQA) of emulsion product in demonstrating physicochemical equivalence using difluprednate (DFPN) emulsion product Durezol® as a model, we developed a novel low-field benchtop NMR method to demonstrate its applicability in measuring DFPN phase partition for ophthalmic oil-in-water emulsion products. Low-field ¹⁹F spectra were collected for DFPN in formulation, in water phase and oil phase after separation from ultra-centrifugation. The NMR data showed the mass balance of DFPN before and after phase separation. The average water phase content of different Durezol® lots was 32 ± 3% with 1% variation from method reproducibility test. The partition results were 52 ± 2% for the in-house control products prepared in Q1/Q2 equivalence to Durezol® but by a different process. The significant difference in DFPN-phase partition between Durezol® and the in-house formulation demonstrated manufacture difference readily changed the API partition. The newly developed ultra-centrifugation and ¹⁹F NMR by benchtop instrument is a simple, robust, and sensitive analytical method for ophthalmic emulsion drug product development and control.