Topical SCD-153, a 4-methyl itaconate prodrug, for the treatment of alopecia areata.

Alopecia areata is a chronic hair loss disorder that involves autoimmune disruption of hair follicles by CD8+  T cells. Most patients present with patchy hair loss on the scalp that improves spontaneously or with topical and intralesional steroids, topical minoxidil, or topical immunotherapy. However, recurrence of hair loss is common, and patients with extensive disease may require treatment with oral corticosteroids or oral Janus kinase (JAK) inhibitors, both of which may cause systemic toxicities with long-term use. Itaconate is an endogenous molecule synthesized in macrophages that exerts anti-inflammatory effects. To investigate the use of itaconate derivatives for treating alopecia areata, we designed a prodrug of 4-methyl itaconate (4-MI), termed SCD-153, with increased lipophilicity compared to 4-MI (CLogP 1.159 vs. 0.1442) to enhance skin and cell penetration. Topical SCD-153 formed 4-MI upon penetrating the stratum corneum in C57BL/6 mice and showed low systemic absorption. When added to human epidermal keratinocytes stimulated with polyinosinic-polycytidylic acid (poly I:C) or interferon (IFN)γ, SCD-153 significantly attenuated poly I:C-induced interleukin (IL)-6, Toll-like receptor 3, IL-1ß, and IFNß expression, as well as IFNγ-induced IL-6 expression. Topical application of SCD-153 to C57BL/6 mice in the resting (telogen) phase of the hair cycle induced significant hair growth that was statistically superior to vehicle (dimethyl sulfoxide), the less cell-permeable itaconate analogues 4-MI and dimethyl itaconate, and the JAK inhibitor tofacitinib. Our results suggest that SCD-153 is a promising topical candidate for treating alopecia areata.

Plasma and cerebrospinal fluid pharmacokinetics of vodobatinib, a neuroprotective c-Abl tyrosine kinase inhibitor for the treatment of Parkinson's disease.

BACKGROUND: Preclinical evidence suggests that c-Abl is critical in the pathogenesis of Parkinson's Disease (PD). Vodobatinib (K0706) is a potent, specific Abl kinase inhibitor currently being developed for the treatment of PD. In previously reported studies, nilotinib, a multikinase c-Abl inhibitor, did not show clinical activity as evidenced by no improvement of symptoms or the rate of decline after one to six months of treatment at the maximum permissible dose, presumably because of insufficient CNS penetration. Here we report clinical PK and safety data for vodobatinib. OBJECTIVES: To determine safety, plasma PK, and CSF penetration of vodobatinib in healthy volunteers and PD subjects following oral administration, and compare CSF levels to in vitro concentrations required for c-Abl inhibition relative to data reported for nilotinib. METHODS: Inhibition of c-Abl kinase activity and c-Abl binding affinity were first assessed in vitro. Healthy human volunteers and PD patients received various oral doses of vodobatinib once-daily for seven and fourteen days respectively, to assess safety, and plasma and CSF PK. RESULTS: In in vitro assays, vodobatinib was more potent (kinase IC50 = 0.9 nM) than nilotinib (kinase IC50 = 15-45 nM). Administration of vodobatinib 48, 192 and 384 mg to healthy subjects for 7 days yielded mean Cmax, CSF values of 1.8, 11.6, and 12.2 nM respectively, with the two highest doses exceeding the IC50 over the entire dosing interval. Cavg, CSF values were 6-8 times greater than the IC50. Comparable CSF levels were observed in PD patients. All doses were well tolerated in both cohorts. CONCLUSION: Based on achieved CSF concentrations, the potential for c-Abl inhibition in the brain is substantially higher with vodobatinib than with nilotinib. The CSF PK profile of vodobatinib is suitable for determining if c-Abl inhibition will be neuroprotective in PD patients.

Pharmacokinetics of intranasal mometasone in the fixed-dose combination GSP301 versus two monotherapy intranasal mometasone formulations.

BACKGROUND: GSP301 is a fixed-dose combination (FDC) of the antihistamine olopatadine hydrochloride and the corticosteroid mometasone furoate developed as a single nasal spray (NS). OBJECTIVE: To assess the relative bioavailability of mometasone administered as GSP301 FDC versus two mometasone monotherapy NS formulations. METHODS: In this single-dose, open-label, crossover study, healthy adults (age range, 18-65 years) were randomized equally to one of six treatment sequences for three 72-hour treatment periods with GSP301 (olopatadine 665 µg-mometasone 50 µg), the mometasone furoate monotherapy component of GSP301 (MF-sponsor, 50 µg), and U.S. Food and Drug Administration-approved mometasone (MF, 50 µg); all the treatments were administered as two sprays per nostril. To evaluate the relative bioavailability of mometasone, pharmacokinetic (PK) estimates, the maximum plasma concentration (Cmax), the area under the plasma concentration time curve (AUC) from time 0 to the last time point with measurable concentration (AUC0-t), and AUC from time 0 to time infinity (AUC0-∞) were compared by analysis of variance. Safety and tolerability were also assessed. RESULTS: A total of 30 healthy subjects were randomized. Most subjects were white men who were not obese, mean age of ∼43 years. The geometric mean ratios for natural log transformed Cmax, AUC0-t, and AUC0-∞ of mometasone in GSP301 to MF-sponsor were 113.83, 118.36, and 118.50, respectively. For GSP301 and MF, geometric mean ratios for Cmax, AUC0-t, and AUC0-∞ were 141.84, 109.92, and 115.14, respectively. The percentages of subjects who reported treatment-emergent adverse events (TEAE) were 10.0%, 13.3%, and 10.3% for GSP301, MF-sponsor, and MF treatments, respectively. All TEAEs were mild, and none resulted in discontinuation. CONCLUSION: Mometasone bioavailability with GSP301 was comparable with MF-sponsor and MF monotherapies. A slightly higher Cmax was observed with GSP301 than with MF, but AUC was comparable. The addition of olopatadine to mometasone in GSP301 did not considerably affect the PK of mometasone. GSP301 was well tolerated, with only mild adverse events reported.

Pharmacokinetics of intranasal olopatadine in the fixed-dose combination GSP301 versus two monotherapy intranasal olopatadine formulations.

BACKGROUND: GSP301 is a fixed-dose combination of the antihistamine olopatadine hydrochloride and the corticosteroid mometasone furoate developed as a single nasal spray. OBJECTIVE: To assess the relative bioavailability of olopatadine administered as GSP301 versus two olopatadine monotherapy nasal spray formulations. METHODS: In this single-dose, open-label, crossover study, healthy adults (18-65 years old) were equally randomized to one of six treatment sequences for three 48-hour treatment periods with GSP301 (olopatadine 665 µg-mometasone 50 µg), the olopatadine monotherapy component of GSP301 (OLO-sponsor; 665 µg) and U.S. Food and Drug Administration approved olopatadine (OLO; 665 µg); each treatment was administered as a single dose (two sprays in each nostril). To assess the relative bioavailability of olopatadine in the fixed-dose nasal spray versus two monotherapies, pharmacokinetic (PK) estimates, maximum plasma concentration (Cmax), area under the plasma concentration time curve (AUC) from time 0 to the last time point with measurable concentration (AUC0-t), and AUC from time 0 to time infinity (AUC0-∞) were compared by analysis of variance. Safety and tolerability were also evaluated. RESULTS: A total of 30 healthy adults (mean age, 43.1 years) were randomized. The majority of the subjects were white men. The geometric mean ratios for natural log transformed Cmax, AUC0-t, and AUC0-∞ of olopatadine in GSP301 and OLO-sponsor were 86.63, 86.92, and 92.83, respectively. For GSP301 and OLO, geometric mean ratios for Cmax, AUC0-t, and AUC0-∞ were 84.68, 87.87, and 93.80, respectively. The percentage of subjects who reported treatment-emergent adverse events (AE) for GSP301, OLO-sponsor, and OLO were 13.8, 10.3, and 10.0%, respectively, with mild AEs reported. One subject withdrew from the study due to an AE (minor oropharyngeal pain) during OLO treatment, before receiving GSP301. CONCLUSION: Olopatadine bioavailability with GSP301 was comparable with OLO-sponsor and OLO. The presence of mometasone in GSP301 did not considerably affect the PK of olopatadine. GSP301 was well tolerated, with only mild AEs reported.

Pharmacokinetics of Stereoisomeric Dipeptide Prodrugs of Acyclovir Following Intravenous and Oral Administrations in Rats: A Study Involving In vivo Corneal Uptake of Acyclovir Following Oral Dosing.

OBJECTIVE: To delineate the plasma pharmacokinetics and determine the corneal uptake of valine based stereoisomeric dipeptide prodrugs of acyclovir (ACV) in rats. METHODS: Male Sprague-Dawley rats were used for the study. Pharmacokinetics of ACV, L-valine-acyclovir (LACV), L-valine-D-valine-acyclovir (LDACV) and D-valine-L-valine acyclovir (DLACV) prodrugs were delineated. These compounds were administered intravenously as a bolus via jugular vein cannula and orally by gavage. Samples were purified by protein precipitation method and analyzed by LC-MS/MS. Pertinent pharmacokinetic parameters were obtained by using WinNonlin. Corneal uptake studies of LDACV and LACV were studied following oral administration. RESULTS: Following i.v. administration, the area under the curve (AUC) in µM*min of generated ACV was in the order of LACV > LDACV > DLACV indicating their rate of metabolism. The AUC values of total drug obtained in the systemic circulation after oral administration LACV and LDACV were 1077.93 ± 236.09 and 1141.76 ± 73.67 µM*min, respectively. DLACV exhibited poor oral absorption. Cmax (µM) and AUC of the intact prodrug obtained in the systemic circulation following oral administration of LDACV were almost 4-5 times higher than LACV. Moreover, concentrations achieved in the cornea after oral administration of LDACV were almost two times of LACV. CONCLUSIONS: LDACV increased both the oral bioavailability and subsequent in vivo corneal uptake of ACV. Hence, LDACV can be considered as the most promising drug candidate for delivery of ACV, in treatment of both genital herpes and ocular herpes keratitis after oral administration.

Disposition kinetics of a dipeptide ester prodrug of acyclovir and its metabolites following intravenous and oral administrations in rat.

The objective of this work was to study the disposition kinetics of valine-valine-acyclovir (VVACV), a dipeptide ester prodrug of acyclovir following intravenous and oral administrations in rat. A validated LC-MS/MS analytical method was developed for the analysis VVACV, Valine-Acyclovir (VACV), and Acyclovir (ACV) using a linear Ion Trap Quadrupole. ACV was administered orally for comparison purpose. In the VVACV group, both blood and urine samples and in the ACV group only blood samples were collected. All the samples were analyzed using LC-MS/MS. The LLOQ for ACV, VACV, and VVACV were 10, 10, and 50 ng/ml, respectively. Relevant pharmacokinetic parameters were obtained by non-compartmental analyses of data with WinNonlin. Following i.v. administration of VVACV, AUC(0-inf) (min*µM) values for VVACV, VACV, and ACV were 55.06, 106, and 466.96, respectively. The AUC obtained after oral administration of ACV was 178.8. However, following oral administration of VVACV, AUC(0-inf) values for VACV and ACV were 89.28 and 810.77, respectively. Thus the exposure of ACV obtained following oral administration of VVACV was almost 6-fold higher than ACV. This preclinical pharmacokinetic data revealed that VVACV has certainly improved the oral bioavailability of ACV and is an effective prodrug for oral delivery of ACV.

Synthesis, metabolism and cellular permeability of enzymatically stable dipeptide prodrugs of acyclovir.

The objective of this study was to synthesize and evaluate novel enzymatically stable dipeptide prodrugs for improved absorption of acyclovir. l-Valine-l-valine-acyclovir (LLACV), l-valine-d-valine-acyclovir (LDACV), d-valine-l-valine-acyclovir (DLACV) and d-valine-d-valine-acyclovir (DDACV) were successfully synthesized. The uptake and transport studies were conducted on a Caco-2 cell line. Buffer stability and metabolism of the prodrugs in Caco-2, rat intestine and liver homogenates were studied. Structure and purity of the all compounds were confirmed with LC-MS/MS and NMR spectroscopy. Uptake and transport of [(3)H] glycylsarcosine was inhibited by all prodrugs except DDACV. DLACV and DDACV exhibited no measurable degradation in Caco-2 homogenate. Except DDACV other three prodrugs were hydrolyzed in rat intestine and liver homogenates. The order of permeability across Caco-2 was LDACV>LLACV>DDACV>DLACV. A linear correlation between the amount of prodrug transported and over all permeability of acyclovir was established. This study shows that the incorporation of one d-valine in a dipeptide did not abolish its affinity towards peptide transporters (PEPT). Moreover, it enhanced enzymatic stability of prodrug to a certain extent depending on the position in a dipeptide conjugate. This strategy improved both the cellular permeability and the amount of intact prodrug transported which would enable targeting the nutrient transporters at blood ocular barrier (BOB).

Functional activity of a large neutral amino acid transporter (LAT) in rabbit retina: a study involving the in vivo retinal uptake and vitreal pharmacokinetics of L-phenyl alanine.

PURPOSE: The purpose of this study is to elucidate the functional activity of large neutral amino acid transporter (LAT) in rabbit retina and to delineate its role in the retinal uptake and intravitreal pharmacokinetics of L-phenylalanine (L-Phe). METHODS: In vivo retinal uptake of L-Phe and L-alanine (L-Ala) was determined in the presence and absence of specific transport inhibitors following intravitreal administration. L and D isomers of amino acids were employed as inhibitors to determine the stereo-selectivity of LAT. Reverse transcription-polymerase chain reaction (RT-PCR) was carried out for LAT isoforms (LAT1 and LAT2). Vitreal disposition of L-Phe following administration in rabbit vitreous was studied in the presence of an other competing LAT substrate D-methionine using microdialysis. RESULTS: Retinal uptake of L-Phe was significantly inhibited in presence of a specific LAT inhibitor, 2-aminobicyclo-[2,2,1]-heptane-2-carboxylic acid (BCH), L isomers of large neutral amino acids and LAT1 specific but not by LAT2 specific and charged amino acids. No significant inhibition of L-Ala retinal uptake was observed with LAT substrates. LAT isoforms (LAT1 and LAT2) were identified by RT-PCR in rabbit retina. The mean residence time (MRT) and area under curve (AUC) values of L-Phe following intravitreal administration were significantly increased in the presence of D-methionine, a LAT substrate. CONCLUSIONS: This study demonstrates the functional activity and molecular expression of large neutral amino acid transporter in the rabbit retina. Furthermore, based on these studies it can be concluded that LAT is involved in the retinal uptake and intravitreal elimination of L-Phe.

Mechanism of L-ascorbic acid uptake by rabbit corneal epithelial cells: evidence for the involvement of sodium-dependent vitamin C transporter 2.

PURPOSE: To investigate the mechanism of L-ascorbic acid uptake by rabbit corneal epithelial cells and to functionally characterize the specific transporter involved in this translocation process. METHODS: Uptake studies were carried out with SIRC (Statens Seruminstitut Rabbit Cornea) and rPCEC (rabbit Primary corneal epithelial cell culture) in 12-well plates using [14C] Ascorbic acid (AA). Uptake was done in the presence of L-ascorbic acid and D-isoascorbic acid to delineate stereospecificity. Inhibition studies were performed in the presence of D-glucose a substrate for GLUT and also para amino hippuric acid (PAHA) a substrate for organic anion transporter. Effects of pH and sodium on the uptake of AA were characterized. Concentration dependency studies were performed. Energy dependence of AA uptake was investigated with ouabain and sodium azide in rPCEC. Reverse Transcription-polymerase chain reaction (RT-PCR) was also performed. RESULTS: Uptake of AA was inhibited by about 90% and 50% respectively in the presence of L-ascorbic acid and D-isoascorbic acid in both SIRC and rPCEC. Uptake was unaltered by D-glucose and PAHA. The process was sodium dependent and saturable at higher concentrations. Ouabain and sodium azide significantly diminished the uptake process. It also decreased with a reduction in pH. The RT-PCR results showed the presence of SVCT2 but not SVCT1. CONCLUSIONS: Uptake of AA across rabbit corneal epithelial cells appears to be a carrier mediated active process. A saturable, sodium dependent, and pH sensitive transporter with high specificity for L-ascorbic acid was functionally characterized and was identified as SVCT2.

Modulation of P-glycoprotein-mediated efflux by prodrug derivatization: an approach involving peptide transporter-mediated influx across rabbit cornea.

The aim of this study was to investigate the modulation of efflux mechanisms using transporter- targeted prodrug derivatization of a model P-gp substrate, quinidine. The L-valine, L-valine-valine esters of quinidine, val-quinidine (VQ), and val-val-quinidine (VVQ) were synthesized in our laboratory, respectively. [(14)C] erythromycin was chosen to delineate the affinity of quinidine (Q) toward P-gp. [(3)H] glycylsarcosine (GS, or glysar) was chosen as a model peptide transporter (PEPT) substrate. Uptake studies were performed on rPCEC (rabbit primary corneal epithelial culture) using 12-well plates. Transport studies were conducted with isolated rabbit corneas at 34 degrees C. Efflux of [(14)C] erythromycin was significantly increased in the presence of quinidine, whereas it was unaltered in the presence of VQ and VVQ. VVQ was more stable, both in buffers and tissue homogenate. Transport of VQ and VVQ was inhibited with GS, and their permeability values were 1.5 and 3 times higher than the permeability of quinidine, respectively. Results from this study clearly indicate that prodrug derivatization of quinidine can modulate P-gp-mediated efflux. These prodrugs have a reduced or diminished affinity toward P-gp and were further recognized by the peptide transporter- mediated process. Enhanced permeabilities of the prodrugs indicate that drug derivatization can be a viable strategy for overcoming P-gp-mediated efflux.

Simultaneous modulation of transport and metabolism of acyclovir prodrugs across rabbit cornea: An approach involving enzyme inhibitors.

The aim of this study is to identify the class of enzymes responsible for the hydrolysis of amino acid and dipeptide prodrugs of acyclovir (ACV) and to modulate transport and metabolism of amino acid and dipeptide prodrugs of acyclovir by enzyme inhibitors across rabbit cornea. l-Valine ester of acyclovir, valacyclovir (VACV) and l-glycine-valine ester of acyclovir, gly-val-acyclovir (GVACV) were used as model compounds. Hydrolysis studies of VACV and GVACV in corneal homogenate were conducted in presence of various enzyme inhibitors. IC(50) values were determined for the enzyme inhibitors. Transport studies were conducted with isolated rabbit corneas at 34 degrees C. Complete inhibition of VACV hydrolysis was observed in the presence of Pefabloc SC (4-(2-aminoethyl)-benzenesulfonyl-fluoride) and PCMB (p-chloromercuribenzoic acid). Similar trend was also observed with GVACV in the presence of bestatin. IC(50) values of PCMB and bestatin for VACV and GVACV were found to be 3.81+/-0.94 and 0.34+/-0.08muM respectively. Eserine, tetraethyl pyrophosphate (TEPP) and diisopropyl fluorophosphate (DFP) also produced significant inhibition of VACV hydrolysis. Transport of VACV and GVACV across cornea showed decreased metabolic rate and modulation of transport in presence of PCMB and bestain respectively. The principle enzyme classes responsible for the hydrolysis of VACV and GVACV were carboxylesterases and aminopeptidases respectively. Enzyme inhibitors modulated the transport and metabolism of prodrugs simultaneously even though their affinity towards prodrugs was distinct. In conclusion, utility of enzyme inhibitors to modulate transport and metabolism of prodrugs appears to be promising strategy for enhancing drug transport across cornea.