A prospective cross-sectional study on hypocalcemia after total thyroidectomy in patients with Graves' disease: insights on secondary hyperparathyroidism.

PURPOSE: To investigate the parathyroid function and calcium (Ca) levels in the secondary hyperparathyroidism (SHPT) state in patients with Graves' disease. METHODS: We examined 31 consecutive patients with Graves' disease without chronic kidney disease, who were treated with total thyroidectomy. The patients were divided into a normal parathyroid hormone (PTH) group (NPTH group; n = 19) with a PTH level ≤ 65 pg/mL, and a secondary hyperparathyroidism group (SHPT group; n = 12), with a PTH level > 65 pg/mL. The PTH and Ca-related parameters were examined and the risk factors for postoperative hypocalcemia were analyzed. RESULTS: The preoperative Ca level was significantly lower (2.24 ± 0.06 vs. 2.31 ± 0.07 mmol/L, p < 0.05) in the SHPT group than in the NPTH group. The reduction in PTH, 1,25-dihydroxyvitamin D (1,25(OH)2D), and Ca levels from the preoperative day to the next morning was significantly greater in the SHPT group than in the NPTH group (p < 0.05). When intraoperative factors were included, the decrease in the PTH level alone was significant. SHPT was a significant factor in determining the extent of PTH reduction. CONCLUSIONS: Hyperfunctioning parathyroid glands in the SHPT state were more susceptible to postoperative PTH reduction, which, combined with low preoperative Ca levels, increased the risk of postoperative hypocalcemia in patients with Graves' disease.

Extracellular aaRSs drive autoimmune and inflammatory responses in rheumatoid arthritis via the release of cytokines and PAD4.

OBJECTIVES: Recent studies demonstrate that extracellular-released aminoacyl-tRNA synthetases (aaRSs) play unique roles in immune responses and diseases. This study aimed to understand the role of extracellular aaRSs in the pathogenesis of rheumatoid arthritis (RA). METHODS: Primary macrophages and fibroblast-like synoviocytes were cultured with aaRSs. aaRS-induced cytokine production including IL-6 and TNF-α was detected by ELISA. Transcriptomic features of aaRS-stimulated macrophages were examined using RNA-sequencing. Serum and synovial fluid (SF) aaRS levels in patients with RA were assessed using ELISA. Peptidyl arginine deiminase (PAD) 4 release from macrophages stimulated with aaRSs was detected by ELISA. Citrullination of aaRSs by themselves was examined by immunoprecipitation and western blotting. Furthermore, aaRS inhibitory peptides were used for inhibition of arthritis in two mouse RA models, collagen-induced arthritis and collagen antibody-induced arthritis. RESULTS: All 20 aaRSs functioned as alarmin; they induced pro-inflammatory cytokines through the CD14-MD2-TLR4 axis. Stimulation of macrophages with aaRSs displayed persistent innate inflammatory responses. Serum and SF levels of many aaRSs increased in patients with RA compared with control subjects. Furthermore, aaRSs released PAD4 from living macrophages, leading to their citrullination. We demonstrate that aaRS inhibitory peptides suppress cytokine production and PAD4 release by aaRSs and alleviate arthritic symptoms in a mouse RA model. CONCLUSIONS: Our findings uncovered the significant role of aaRSs as a novel alarmin in RA pathogenesis, indicating that their blocking agents are potent antirheumatic drugs.

Usefulness of preoperative ice cream consumption and novel postoperative drainage management in patients undergoing left-sided neck dissection for thyroid cancer: a nonrandomized prospective study.

PURPOSE: This study investigated the effects of ice cream consumption on chyle leakage after left lateral neck dissection in patients with thyroid cancer. METHODS: A total of 491 patients with thyroid cancer underwent left lateral neck dissection with identification of the thoracic duct following ice cream consumption. Before closing the wound, the anesthesiologist increased the intrathoracic pressure to observe chyle leakage. If chyle leakage occurred postoperatively, the drain was removed using the drain negative pressure release test. RESULTS: Postoperative chyle leakage was observed in 18 of the 491 patients who underwent left lateral neck dissection. We treated 17 patients conservatively and 1 patient surgically. Drains were removed within five days in all patients. After the drain negative pressure release test had been performed in eight patients, the drainage volume significantly decreased from an average of 175 ml to 31 ml per day. The average number of days until the removal of the drainage tube was 3.2 days. No perioperative complications were associated with ice cream consumption. CONCLUSIONS: In left lateral neck dissection for thyroid cancer, performing surgery following ice cream consumption does not completely prevent chyle leakage; however, early drain removal is possible because there is only mild leakage.

Anti-Zo antibodies in Japanese myositis patients detected by a newly developed ELISA.

OBJECTIVES: The myositis-specific autoantibodies that characterise certain forms of idiopathic inflammatory myopathy (IIM) are useful for diagnosing dermatomyositis (DM) / polymyositis (PM) and predicting its prognosis. The autoantibody to phenylalanyl-tRNA synthetase (anti-Zo) has been identified as a disease marker antibody for anti-synthetase syndrome only in a UK cohort. Here we aim to establish an ELISA for the measurement of anti-Zo and to characterise the clinical features of Japanese patients who have this autoantibody. METHODS: Anti-Zo was investigated by immunoprecipitation with recombinant phenylalanyl-tRNA synthetase α/ß proteins. The results were confirmed by immunoprecipitation-Western blotting with cell extract. Sera from patients with DM/PM (n=224) were screened by an ELISA with the recombinant proteins. Medical records were retrospectively reviewed to obtain detailed information on the clinical phenotypes of the anti-Zo-positive patients. RESULTS: Only two male patients were confirmed to have anti-Zo. Both patients had fever, myopathy, interstitial lung disease, and mechanic's hands, and these clinical features are consistent with those of anti-synthetase syndrome. Another patient's serum showed a higher level than the cut-off value for anti-phenylalanyl-tRNA synthetase α by our in-house ELISA, but was judged to be negative for anti-Zo by immunoprecipitation-Western blotting. CONCLUSIONS: This is the first report of anti-Zo-positive IIM patients from Asia. Although Japanese patients with anti-Zo have a clinical phenotype similar to that of Caucasian patients, further large cohort studies are necessary to confirm the frequency of anti-Zo in Japanese IIM patients. Our newly developed ELISA should be validated for sensitivity and specificity in large cohorts.

Gestational Outcomes and Birth Weight in Japanese Women at the Upper and Lower limits of the Normal BMI range.

To examine the outcome of gestational blood pressure and birth weight in women with normal pre-pregnancy BMI (18.5-25 kg/m2) who are at the lower and upper limits of this range, i.e., slightly underweight or slightly overweight. Overall, 2,038 Japanese women with low -risk who had delivered during January 2014-December 2016 were classified according to their pre-pregnancy BMI: underweight (< 18.5 kg/m2), slightly underweight (18.5≤BMI<21 kg/m2), normal (21≤BMI<23 kg/m2), slightly overweight (23≤BMI<25 kg/m2) and overweight (≤ 25 kg/m2). Their blood pressure during each trimester and birth weight was evaluated. The slightly overweight group showed a significantly higher blood pressure than the underweight and slightly underweight groups. Birth weight was lower in the slightly underweight than in the slightly overweight group (p<0.01). The incidence rate of "heavy for dates" (HFD) infants was significantly higher in the slightly overweight and overweight groups than in the other groups (p<0.05 and p<0.01, respectively). Weight gain of < 7 kg significantly increased the rate of "light for dates" (LFD) infants, while a weight gain of ≥13 kg significantly increased the rate of HFD infants (p<0.05 and p<0.01, respectively). Blood pressure during pregnancy was ssociated with pre-pregnancy BMI. The birth weight of infants of low-risk pregnant women is affected by both pre-pregnancy BMI and gestational weight gain.

A New Indicator to Differentiate Thyroid Follicular Inclusions in Cervical Lymph Nodes from Patients with Thyroid Cancer.

Nodal metastasis is crucial for determining the stage of well-differentiated thyroid cancer (WTC) in patients older than 55. Well-formed thyroid follicular inclusions (TFIs) are occasionally encountered in the cervical lymph nodes (LNs) of patients with papillary thyroid carcinoma (PTC), and it is difficult to determine whether they are true nodal metastases or ectopic thyroid tissues (ETT). This study aimed to elucidate the impact of the expression of the DNA damage response molecule TP53-binding protein 1 (53BP1) using immunofluorescence (IF) as a biomarker to differentiate TFIs in cervical LN by comparing the mutation analyses of primary thyroid cancers. The data demonstrated the necessity for the differential diagnosis of true metastases from ETT among TFIs in cervical LNs. PTC-like nuclear features using hematoxylin-eosin staining combined with immunohistochemistry for conventional biomarkers of PTC, including BRAFV600E protein, were most helpful in identifying metastatic follicular-patterned carcinomas. In conclusion, IF analysis of 53BP1 expression could be an excellent ancillary technique to distinguish metastatic carcinoma or ETT from TFIs in LNs, particularly in cases other than BRAFV600E-mutated PTC.

Acute exacerbation of rheumatoid arthritis-associated interstitial lung disease: clinical features and prognosis.

OBJECTIVES: RA-associated interstitial lung disease (RA-ILD) is commonly associated with acute exacerbations (ILD-AE). This study examined the clinical characteristics and risk factors of ILD-AE and mortality of RA-ILD. METHODS: We retrospectively collected data on 165 RA-ILD patients who visited or were admitted to our hospital between January 2007 and December 2019. We compared the clinical characteristics of patients who did and did not develop ILD-AE and identified variables significantly associated with ILD-AE. We also compared the admission characteristics of those who survived and those who died after admission for ILD-AE. ILD-AE was defined using previously proposed criteria, modified slightly for application to RA-ILD. RESULTS: The mean patient age was 73.6 years (s.d. 9.7) and 97 (71.9%) patients were female. Thirty (22.2%) patients developed ILD-AE, 13 (43.3%) of whom died. In univariate analyses, neither the usual interstitial pneumonia (UIP) pattern nor MTX was associated with ILD-AE. In multivariate analyses, the UIP pattern was significantly associated with ILD-AE [odds ratio (OR) 2.55 (95% CI 1.05, 6.20), P = 0.038]. In the Cox proportional hazards model, the UIP pattern [hazard ratio (HR) 4.67 (95% CI 1.02, 21.45), P = 0.048] was significantly associated with death, while MTX use [HR 0.16 (95% CI 0.04, 0.72), P = 0.016] was significantly associated with survival. CONCLUSION: Our data suggest that the UIP pattern is related to ILD-AE. Furthermore, both the UIP pattern and non-use of MTX might be related to death from ILD-AE in RA-ILD.

Adverse drug reactions to trimethoprim-sulfamethoxazole in systemic lupus erythematosus.

OBJECTIVES: Trimethoprim-sulfamethoxazole (TMP-SMX), a prophylactic agent against pneumocystis pneumonia (PCP), can cause adverse drug reactions (ADRs), particularly in patients with systemic lupus erythematosus (SLE). However, the risk factors for ADRs remain unclear. Thus, we sought to examine the prevalence of TMP-SMX-related ADRs in patients with SLE and identify specific risk factors for ADR development in these patients. METHODS: We retrospectively reviewed data from patients with connective tissue disease (CTD) who were administered TMP-SMX as a PCP prophylactic. The prevalence of ADRs was compared between patients with SLE and those with other CTDs. Univariate and multivariate analyses were conducted to identify risk factors for ADRs in patients with SLE. RESULTS: Of the 424 patients with CTD included in our study (SLE, n = 162; other CTDs, n = 262), 22 with SLE (13.6%) developed ADRs, and this rate was significantly higher than that observed in patients with non-SLE CTDs (n = 18 [6.9%], p = 0.033). In patients with SLE, univariate analyses revealed direct associations of ADRs with anti-Sm (p < 0.001), anti-RNP (p = 0.02), and anti-Ro/SS-A antibodies (p = 0.042). Multivariate analysis identified a significant association between anti-Sm antibody levels and the development of ADRs (adjusted odds ratio 5.27, 95% confidence interval 1.80-15.40, p = 0.002). CONCLUSIONS: Patients with SLE who are prophylactically administered TMP-SMX are at high risk of ADRs. Among these patients, those who display a positive anti-Sm antibody should be carefully monitored for ADRs.

A case of recurrence of adult-onset Still's disease in the third trimester: a case report and literature review.

BACKGROUND: Adult-onset Still's disease (AOSD) is a self-inflammatory disease showing macrophage and neutrophil activation by inflammatory cytokines such as TNF-α, IL-6, and IL-18. Although some cases with the flare of AOSD during pregnancy have been reported, most had flares in the first or second trimester and few had flares in the third trimester. In this report, we present the case of a patient with recurrent flare of AOSD in the third trimester and discuss the management of AOSD in the third trimester with the review of previous literatures. CASE PRESENTATION: A 38-year-old woman in complete AOSD remission without medication presented with impaired liver function, low platelet count, mild fever, abdominal pain, splenomegaly, and elevated ferritin and IL-18 levels at 30 gestational weeks. Although the laboratory data and physical examination finding suggested HELLP syndrome or acute fatty liver of pregnancy and we considered the termination of her pregnancy, her fetus was in a reactive status. Considering her fetal status, some specific findings of AOSD, and her AOSD history, we and rheumatologists diagnosed her with AOSD recurrence and started systemic steroid therapy. In her clinical course, three flares of AOSD occurred, twice in the third trimester and once in postpartum; twice systemic steroid pulse therapies were then needed. Ultimately, a healthy infant was delivered transvaginally at 36 gestational weeks spontaneously. CONCLUSIONS: Specific findings of the flare of AOSD such as fever, splenomegaly, elevated ferritin and IL-18 levels, and fetal status could be useful findings for differentiation from HELLP syndrome and AFLP in the third trimester. With the careful management supported by rheumatologists, patients complicated with the flare of AOSD may continue their pregnancy longer than we expected.

Impact of adding tacrolimus to initial treatment of interstitial pneumonitis in polymyositis/dermatomyositis: a single-arm clinical trial.

OBJECTIVE: Interstitial pneumonia is common and has high short-term mortality in patients with PM and DM despite glucocorticoid (GC) treatment. Retrospective studies suggested that the early use of immunosuppressive drugs with GCs might improve its short-term mortality. METHODS: A multicentre, single-arm, 52-week-long clinical trial was performed to test whether the initial combination treatment with tacrolimus (0.075 mg/kg/day, adjusted for the target whole-blood trough levels between 5 and 10 ng/ml) and GCs (0.6-1.0 mg/kg/day of prednisolone followed by a slow taper) improves short-term mortality of PM/DM-interstitial pneumonia patients. The primary outcome was overall survival. We originally intended to compare, by using propensity-score matching, the outcome data of clinical trial patients with that of historical control patients who were initially treated with GCs alone. RESULTS: The 52-week survival rate with the combination treatment (N = 26) was 88.0% (95% CI, 67.3, 96.0). Safety profiles of the combination treatment were consistent with those known for tacrolimus and high-dose GCs individually. Serious adverse events occurred in 11 patients (44.0%), which included four opportunistic infections. Only 16 patients, including only 1 deceased patient, were registered as historical controls, which precluded meaningful comparative analysis against the clinical trial patients. CONCLUSION: Our study provided findings which suggest that initial treatment with tacrolimus and GCs may improve short-term mortality of PM/DM-interstitial pneumonia patients with manageable safety profiles. This was the first prospective clinical investigation conducted according to the Good Clinical Practice Guideline of the International Conference on Harmonization for the treatment of this potentially life-threatening disease. TRIAL REGISTRATION: ClinicalTrials.gov, http://clinicaltrials.gov, NCT00504348.

Material-Sparing and Expedited Development of a Tablet Formulation of Carbamazepine Glutaric Acid Cocrystal- a QbD Approach.

PURPOSE: To efficiently develop a tablet formulation of carbamazepine using a soluble cocrystal with excess coformer to maintain phase stability during dissolution. METHODS: The carbamazepine - glutaric acid cocrystal (CBZ-GLA, 1:1) and excess glutaric acid (GLA) were mixed with suitable tablet excipients, which were selected to address powder flowability and tabletability deficiencies specifically. Tablet friability and dissolution profiles were evaluated to guide formulation optimization. Dry granules were prepared by milling simulated ribbons. RESULTS: A binary blend of CBZ-GLA and GLA had poor flowability and marginal tabletability. Therefore, silica coated Avicel PH-102 (sMCC) was applied as a binder to improve the flow property and tabletability. A formulation consisting of sMCC, CBZ-GLA, and GLA exhibited good manufacturability but did not show improved dissolution because of rapid precipitation of CBZ dihydrate when CBZ-GLA came in contact with water. Dry granulation of CBZ-GLA and GLA dramatically improved dissolution profile due to the intimate contact between CBZ-GLA and GLA. Such cocrystal - coformer granules also led to much improved tablet manufacturability and dissolution. CONCLUSION: The successful tablet development of CBZ-GLA, using < 3 g of the cocrystal in <3 weeks, demonstrates an efficient workflow for tablet formulation development based on material-sparing and predictive powder characterization techniques. This workflow is useful for early tablet development using enabling solid form, such as cocrystal, when only a small amount of material is available.

Fluorodeoxyglucose PET/CT of Arthritis in Rheumatic Diseases: A Pictorial Review.

Rheumatic diseases are various painful conditions that affect joints, bones, cartilage, tendons, ligaments, and muscles. Arthritis is a typical condition of rheumatic disease. Although rheumatoid arthritis is a representative rheumatic disease, various diseases other than rheumatoid arthritis can also affect joints, and differential diagnosis of rheumatic diseases is often difficult owing to the similar clinical manifestations. However, accurate diagnosis is crucial for an appropriate treatment strategy. The utility of fluorine 18 fluorodeoxyglucose (FDG) PET/CT has been established, and it is widely used for assessing malignancies. In addition to accumulating in tumor cells, FDG also accumulates in inflammatory tissue, allowing FDG PET/CT to demonstrate arthritis. PET/CT allows evaluation of whole-body articular and extra-articular lesions in one examination, representing a key advantage over US and MRI, which allow assessment of only a few regions because of their limited field of view. Although FDG PET/CT is sensitive for detecting inflammatory lesions, the uptake itself is nonspecific; therefore, knowledge of characteristic uptake patterns is necessary to narrow the differential diagnosis in rheumatic disease. Furthermore, pathognomonic extra-articular findings such as vasculitis, skin lesions, lymphadenopathy, and chondritis play an important role in achieving accurate diagnosis. The authors present the FDG PET/CT appearances of (a) rheumatoid arthritis and allied disorders (polymyalgia rheumatica, remitting seronegative symmetrical synovitis with pitting edema, adult-onset Still disease), (b) spondyloarthritis (ankylosing spondylitis, psoriatic arthritis, reactive arthritis, inflammatory bowel disease arthritis, SAPHO [synovitis, acne, pustulosis, hyperostosis, and osteitis] syndrome, chronic recurrent multifocal osteomyelitis), and (c) miscellaneous systemic disorders with arthropathy (relapsing polychondritis, multicentric reticulohistiocytosis, amyloidosis, sarcoidosis, hemophilia). ©RSNA, 2020.

Classifications of scleroderma renal crisis and reconsideration of its pathophysiology.

Categorization of scleroderma renal crisis (SRC) as hypertensive or normotensive can potentially overlook the underlying pathophysiology that might be unique in each patient, as they often exhibit a mixture of distinct pathological characteristics of narrowly defined SRC (nd-SRC) and systemic sclerosis associated thrombocytic micro-angiopathy (SSc-TMA). In this review, we provide evidence suggesting that better categorization of patients presenting with certain clinical features of both nd-SRC and TMA will improve treatment approaches. Based on our clinical experience and literature review, distinguishing between nd-SRC and SSc-TMA is important because the association of SSc-TMA with prior steroid administration and poor prognosis was stronger than that of nd-SRC. Although the two pathological entities cannot be easily distinguished based on blood pressure, we suggest that the detailed clinical course is helpful. Typically, nd-SRC exhibits prominently elevated blood pressure and worsening of renal function initially, followed by mild thrombocytopenia. Conversely, SSc-TMA presents first with severe thrombocytopenia, followed by elevated blood pressure and renal function deterioration. The degree of involvement in each pathological condition should be considered for determination of appropriate therapeutic interventions and prognostic prediction.

Expedited Tablet Formulation Development of a Highly Soluble Carbamazepine Cocrystal Enabled by Precipitation Inhibition in Diffusion Layer.

PURPOSE: To address the problem of precipitation of a poorly soluble drug during dissolution of highly soluble cocrystals by preparing granules intimately mixed with a water-soluble polymer. METHODS: Effectiveness of polymers as precipitation inhibitors during the dissolution of carbamazepine-nicotinamide (CBZ-NCT) cocrystal was assessed based on induction time of crystallization from a supersaturated solution in presence of different polymers at two concentrations. Dissolution was evaluated by both intrinsic dissolution rate (IDR) and USP dissolution method. Powder manufacturability was assessed using a shear cell and compaction simulator to assess flowability and tabletability, respectively. RESULTS: Hydroxypropyl methylcellulose acetate succinate (HPMCAS) was the most effective polymer against precipitation of CBZ and the IDR of a 1:1 (w/w) CBZ-NCT/HPMCAS mixture was the highest. The final formulation of 1:1 CBZ-NCT/HPMCAS granule exhibited excellent flowability, good tabletability, and significantly improved drug release rate than cocrystal formulations without HPMCAS or the CBZ formulation. CONCLUSION: The particle engineering strategy of modifying the diffusion layer on the surface of highly soluble cocrystal with a polymer is effective for inhibiting premature precipitation of CBZ. Assisted with predictive tools for characterizing powder flowability and tabletability, the design of high quality tablet product with improved drug release rate and manufacturability can be achieved in an efficient manner.

Clinical characteristics and prognosis of polymyositis and dermatomyositis associated with malignancy: a 25-year retrospective study.

The objective of this study was to identify factors predictive of malignancy in patients with polymyositis (PM) and dermatomyositis (DM) in Japan. We conducted a retrospective study of PM and DM patients who were admitted to our hospital between January 1992 and September 2017. Among 134 patients, 29 (21.6%) were diagnosed with cancer in the 3 years prior to and 3 years after the initial diagnosis of PM or DM. According to multivariate analyses, male sex [odds ratio (OR) = 3.65, p = 0.03], old age (OR = 1.05, p = 0.02), and a past history of diabetes mellitus (OR = 10.4, p = 0.005) were associated with an increased risk of malignancy. The absence of interstitial lung disease (ILD) (OR = 0.25, p = 0.03) was also associated with an increased risk of malignancy. Diabetes mellitus was observed in 28.6% of PM and DM patients with malignancy, but in only 7.3% of those with malignancy. Survival was significantly lower in patients with malignancy than in those without malignancy (p < 0.001). Independent factors associated with malignancies in patients with PM or DM were male sex, old age, the absence of ILD, and, especially, a past history of diabetes mellitus.

Cohort study exploring the effect of lenvatinib on differentiated thyroid cancer.

Lenvatinib is a molecular-targeting agent that was recently approved in Japan for treatment of curatively unresectable, radioactive iodine-refractory, progressive differentiated thyroid cancer (DTC). Because only a few Japanese patients have received lenvatinib in clinical trials, there are limited domestic data on its safety and efficacy or prognostic factors. Therefore, a prospective observational study has been designed to collect safety and efficacy data in at least 300 patients with curatively unresectable DTC receiving lenvatinib therapy (24 mg/day), in order to find predictors of antitumor activity and survival. Patients with progressive curatively unresectable DTC refractory to radioiodine therapy will be enrolled and the primary endpoint will be overall survival. This study is designed to estimate the 95% confidence intervals of the 1-year and 2-year survival rates with a two-sided width of less than 10%. Secondary endpoints will be the time to treatment failure, time to strategy failure, progression-free survival time with clinical progressive disease, response rate, quality of life, safety, and patient reports. The ultimate goal is to obtain information for developing evidence-based guidelines for treatment of DTC, including recommendations on patient selection, dosages, and duration of treatment. This study has been registered with the UMIN Clinical Trials Registry (UMIN000022243).

[Bone and calcium metabolism associated with malignancy. Paraneoplastic rheumatologic musculoskeletal manifestations.]

Patients with malignant tumors may present with joint pain or arthritis(paraneoplastic arthritis). It needs to be carefully determined whether these symptoms are related to the malignant tumor, due to a concomitant rheumatoid disease, due to an adverse reaction to treatment, or due to a relapse. It can be relatively easy to diagnose paraneoplastic syndrome when there is clearly a malignant tumor present or typical symptoms are exhibited. However, clinicians should be aware that these paraneoplastic syndrome phenomena can occur before the malignant tumor is diagnosed. An occult malignancy should be suspected when a patient is elderly and exhibits atypical clinical symptoms of a rheumatic disease;is poorly responsive to usual treatment;or has general symptoms such as weight loss or exhibits suggestive physical findings. In particular, hematological malignancies require careful observations as they do not surface quickly.

Improving Dissolution Rate of Carbamazepine-Glutaric Acid Cocrystal Through Solubilization by Excess Coformer.

PURPOSE: The use of soluble cocrystals is a promising strategy for delivering poorly soluble drugs. However, precipitation of poorly soluble crystal form during dissolution hinders the successful tablet development of cocrystals. This work was aimed to understand the mechanisms for improving dissolution performance of a soluble cocrystals by using excess coformer. METHODS: A highly soluble carbamazepine (CBZ) cocrystal with- glutaric acid (GLA) was studied. Impact of excess GLA on solubility and intrinsic dissolution rate (IDR) was assessed. Viscosity of GLA solutions was also measured. Solid form of powders and pellets was examined using powder X-ray diffractometry. IDRs of cocrystal and GLA mixtures in different ratios were measured to identify a suitable formulation for maintaining high dissolution rate of CBZ-GLA in an aqueous environment. RESULTS: IDR of CBZ-GLA in a pH 1.2 HCl solution was improved when GLA was present in the solution. Precipitation of CBZ·2H2O was eliminated when GLA concentration was ≥100 mg/mL. The improved IDR was accompanied by higher solubility of CBZ in GLA solution and increased solution viscosity. The trend in IDR profile matched well with the solubility profile normalized by solution viscosity. Mixture of cocrystal and GLA led to improved IDR in simulated intestinal fluid. CONCLUSIONS: The excess GLA increased the aqueous solubility of CBZ·2H2O and, thereby, reduced the propensity to precipitation of CBZ·2H2O during dissolution by lowering the degree of supersaturation. This strategy allowed development of a CBZ-GLA formulation with a significantly enhanced dissolution rate than CBZ-GLA.