Population pharmacokinetic modeling of sustained release lithium in the serum, erythrocytes and urine of patients with bipolar disorder.

PURPOSE: Lithium (Li), the first-line treatment of bipolar disorder, was first developed as an immediate-release form with a routine therapeutic drug monitoring 12 h after the last dose. In Europe, the most commonly prescribed form is a sustained release (srLi). Yet no pharmacokinetics (PK) study has been published of srLi, administered once a day, in adults. The present study describes srLi PK in the serum and erythrocytes of bipolar patients. METHODS: To assess srLi PK, we studied prospectively 17 French bipolar patients on a median dose of 1000 mg (600-1600) for at least 2 years. Serum (S), erythrocyte (E) concentrations, and urinary (U) amount were collected over 8 h after 15 days of morning intake using monitoring electronic medical system (MEMs). Population PK parameters were estimated using the SAEM algorithm (MONOLIX 4.3.3 software). RESULTS: Using a population approach, we built a PK population model of srLi including one S compartment (VS = 23.0 L, ClS = 1.21 L h-1), one E compartment (VE = 64.7 L, ClSE = 3.63 L h-1, ClES = 9.46 L h-1), and one U compartment (F = 0.62) and estimate the ratio of concentrations to Li in E over S at 0.38 with 27% between-subject variability. CONCLUSION: This is a PK model of srLi once a day in bipolar patients using a population approach simultaneously describing Li concentrations in serum, erythrocytes, and urine which provide an estimate of the ratio of concentration in erythrocyte over serum and its between-subject variability (BSV).

The hidden face of Wilson's disease.

In brief, the classic form of Wilson's disease (WD) is an autosomal-recessive condition with hepatic, neurologic, psychiatric and systemic manifestations. However, the diagnosis should not be excluded because of a family history consistent with autosomal-dominant transmission. The latest next-generation sequencing (NGS) studies have demonstrated a gap between phenotype and genetic prevalences, and also suggest that WD may still be underdiagnosed. In a majority of WD patients, early recognition and appropriate treatment can result in resolution of symptoms and/or improved quality of life. Thus, finding WD in patients aged>40 years or with thrombocytopenia, hemolytic anemia, unexplained bone pain, amenorrhea, repeated spontaneous abortion or renal lithiasis is of major importance. These symptoms can all be found on their own or in association with mild-to-incapacitating neurological and/or neuropsychiatric manifestations. While brain lesions of the lenticular, midbrain and dentate nuclei are classic, white-matter changes and cortical lesions may also be observed: these are often asymmetrical with frontal lobe predilection and, when extensive, associated with a poor prognosis. These lesions are due mainly to copper deposition, but may also be related to focal accumulation of other metals, such as iron and manganese. A new biological marker called 'relative exchangeable copper' (REC) facilitates diagnosis and familial screening. Patient monitoring is important to ensure treatment adherence, efficacy and tolerability, and to detect rare complications such as copper deficiency induced by chronic copper chelation and hepatocarcinoma in patients with cirrhosis. Currently used treatments are copper chelators and zinc salts. Therapeutic perspectives are liver transplantation, new copper chelators as tetrathiomolybdate, hepatocyte/tissue transfer and gene therapy.

Exchangeable copper: a reflection of the neurological severity in Wilson's disease.

BACKGROUND AND PURPOSE: The severity of Wilson's disease (WD) is linked to free copper accumulating in the liver and brain. Exchangeable copper (CuEXC) is a new technique to determine plasmatic copper and is useful in the diagnosis of WD. It is hypothesized that it may also enable a good evaluation of extra-hepatic involvement and its severity. METHODS: Forty-eight newly diagnosed WD patients were prospectively evaluated using hepatic, neurological, ophthalmological and brain magnetic resonance imaging (MRI) scores. Three phenotypic presentations were distinguished: pre-symptomatic, hepatic and extra-hepatic. CuEXC was determined in addition to standard copper assays before decoppering therapy. Correlations between biological parameters and the different scores were determined and compared in the hepatic and extra-hepatic groups. RESULTS: Extra-hepatic patients had significantly higher CuEXC values than those with the hepatic form (P < 0.0001). The overall ability of CuEXC to separate the two forms was satisfactory, with an area under the curve of 0.883 (95% confidence interval 0.771-0.996) and an optimal threshold for extra-hepatic diagnosis of 2.08 µmol/l (sensitivity 85.7%; specificity 94.1%). In extra-hepatic patients, CuEXC was the only biological marker to be positively correlated with the Unified Wilson Disease Rating Score (r = 0.45, P = 0.016), the Kayser-Fleischer ring score (r = 0.46, P = 0.014) and the brain MRI score (r = 0.38, P = 0.048), but it was not correlated with the hepatic score. CONCLUSIONS: Exchangeable copper determination is useful when diagnosing WD as a value >2.08 µmol/l is indicative of the severity of the extra-hepatic involvement. In the case of purely hepatic presentation, atypical or mild neurological signs, it should encourage physicians to search for lesions in the brain and eyes.