A prefilled, ready-to-use electrophoresis based lab-on-a-chip device for monitoring lithium in blood

We present the Medimate Multireader, the first point-of-care lab on a chip device that is based on capillary electrophoresis. It employs disposable pre-filled microfluidic chips with closed electrode reservoirs and a single sample opening. Several technological innovations allow operation with closed reservoirs, which is essential for reliable point-of-care operation. The chips are inserted into a hand-held analyzer. In the present application, the device is used to measure the lithium concentration in blood. Lithium is quantified by conductivity detection after separation from other blood ions. Measurements in patients show good accuracy and precision, and there is no difference between the results obtained by skilled and non-skilled operators. This point-of-care device shows great promise as a platform for the determination of ionic substances in diagnostics or environmental analysis.

Increased lithium serum and red blood cell concentrations during ketorolac coadministration

Case reports of a lithium-ketorolac drug interaction have been published, but no formal investigation of this interaction has been conducted. The objective of the study presented here was to determine significant changes in lithium serum and red blood cell (RBC) concentrations after lithium and ketorolac (oral formulation) coadministration at steady-state conditions. Five healthy men participated in the study and received lithium 900 mg/day (300 mg in the morning and 600 mg at bedtime) for 13 days. Ketorolac 40 mg/day (10 mg four times a day) was added on days 8 through 12. Ten blood samples were obtained on days 7 and 13 to determine area under the concentration-time curve (AUC) lithium serum and RBC concentrations. Serum and RBC lithium concentrations were assayed by atomic absorption spectrophotometry with an intra-assay coefficient of variation (CV) of 1.2% on day 1 (range 0-1.0 microg/mL) and 4.9% (range 0-1.0 microg/mL) on day 2 and an interassay CV of 2.9% (range 0-1.0 microg/mL) on days 1 and 2 of serum analysis and a CV of 5.3% (range 0-0.3 microg/mL) of RBC concentrations. Total serum AUC lithium and RBC AUC values significantly increased by 24% (p < 0.02) and by 27% (p < 0.05) with the ketorolac coadministration, respectively. An increased incidence and severity of lithium-associated side effects were reported during concomitant administration. A clinically significant drug interaction can occur when ketorolac is added to lithium therapy.

Lithium side effects in relation to brain lithium concentration measured by lithium-7 magnetic resonance spectroscopy

1. The relationship between lithium (Li) side effects and brain Li concentration was examined in 17 patients with bipolar disorder treated with Li and other psychotropic drugs. 2. Brain Li concentration was measured by Li-7 magnetic resonance spectroscopy (MRS). Side effects were assessed using the UCLA General Side Effect Rating Scale For Lithium Treatment (GSE). 3. There was no correlation between the total GSE score and the brain, serum, or erythrocyte Li concentrations. Patients with hand tremor had significantly higher brain Li level (0.51 + or - 0.27 mM) than those without apparent tremor (0.36 + or - 0.20 mM), but no significant difference in serum Li level was seen. As far as the patients had hand tremor, they rarely had brain Li concentration less than the therapeutic range (1 of 15 measurement). On the other hand, they often had brain Li levels less than the therapeutic range when they did not have apparent tremor (13 of 52 measurements). 4. This preliminary study suggests that hand tremor is associated with the brain Li concentration.

Comparison of lithium ratio between African-American and Caucasian bipolar patients

Lithium RBC/plasma ratio (LR) was studied in 34 bipolar subjects on therapeutic doses of lithium carbonate. The sample was divided into 22 Caucasians and 12 African-Americans to observe possible ethnic differences in LR as previously reported. The latter group demonstrated a higher LR as well as increased reports of side effects (p < .05), even after controlling previous confounding factors. Our findings suggest that African-Americans may be more susceptible to the side effects associated with lithium treatment, and consequently, lower dosages may be necessary for this group.

Brain lithium concentrations measured with lithium-7 magnetic resonance spectroscopy in patients with affective disorders: relationship to erythrocyte and serum concentrations

Brain lithium concentrations were measured in eight patients with affective disorders using lithium-7 magnetic resonance spectroscopy (MRS). Brain lithium concentrations correlated better with serum concentrations (n = 23, r = 0.66, p < 0.001) than with erythrocyte concentrations (r = 0.44, p < 0.05). Because of previous data in animal experiments these results were unexpected, but the differences in cation transport mechanisms between neurons and erythrocytes may account for the results.

Determination of lithium in rat brain regions and synaptosomes by graphite furnace atomic absorption spectrophotometry

A graphite furnace atomic absorption spectrophotometric method for the analysis of very low concentrations of lithium in brain tissue and subcellular fractions is described. The method has a picogram sensitivity and shows a precision value of 10.1% expressed as the per cent variation coefficient for the tissue analysis of the metal. Lithium concentration in eight regions of the rat brain and regional synaptosomal lithium contents were analyzed with the method described. Results from these determinations show that lithium is heterogeneously distributed among rat brain regions 24 hr after a single s.c. lithium administration; hypothalamus, corpus striatum and midbrain were the regions with the highest lithium accumulation. Lithium is homogeneously concentrated in the synaptosomes obtained from rat brain regions. The method proposed may be considered adequate for trace lithium analysis in pharmacological studies of the metal.

Renal function in 153 manic-depressive patients treated with lithium for more than five years

Renal function was examined in 153 manic-depressive patients treated with lithium for more than 5 years, mean 10 years. No significant change was detectable in plasma creatinine. Glomerular filtration rate (GFR) decreased slightly, but significantly, and not until after 17 years of treatment did the regression line reach the lower confidence limit in the reference material. GFR was generally only moderately decreased. Renal concentrating capacity was significantly reduced during the whole investigation period and did not change with time. GFR was independent of the dosage pattern. The diuresis did not differ markedly in patients given one or three daily doses. In a two-dose group predominantly treated with slow-release tablets, the diuresis was somewhat higher in 75% of the patients but much higher for the rest of the group. Since the prophylactic effect of lithium was the same in the one-dose group (mean dosage 21 mmol/day) as in the two-dose and three-dose groups (mean dosage 27-28 mmol/day), our data indicate that generally employed lithium doses may be reduced somewhat without loss of prophylactic efficacy.

Observations on lithium disposition in the elderly

The disposition kinetics of lithium were studied in six elderly women who had been maintained on this medication for several years. Lithium administration was stopped abruptly. Plasma, whole blood, and erythrocyte half-lives were then measured, as well as renal plasma clearance and distribution volume. Half-life values in whole blood and in its components were found to be similar. The plasma lithium half-life approximated that in younger schizophrenics, but appeared prolonged when compared with half-lives reported for young normal volunteers. Renal plasma clearance and distribution volume of lithium appeared substantially reduced when compared with published values. The data are consistent with altered lithium disposition in the aged.

Potential pitfalls in the evaluation of the usefulness of hemodialysis for the removal of lithium

A 50-year old female who was comatose from an overdose of lithium was treated with hemodialysis. Serum lithium concentrations declined 47% during a 3-h hemodialysis but increased afterwards, peaking 8 h after hemodialysis was stopped. Hemodialysis clearances were estimated by equations using extraction ratios of lithium from whole blood, serum, and red cells, and flows of whole blood, serum or red cells. The amount of lithium removed was calculated from these clearances as well as measured directly in the dialysate. Errors were introduced into the calculation of the amount of lithium removed by hemodialysis unless whole blood concentrations of lithium and whole blood flows were used. These arose because extraction of lithium from serum (0.7 +/- 0.3, mean +/- SD) was greater than that from whole blood (0.49 +/- 0.06) or from red blood cells (0.18 +/- 0.12). Despite the rapid decrease in serum concentrations of lithium during hemodialysis and rebound afterwards, the patient's neurologic status did not change concurrently. The patient did not regain consciousness until lithium concentrations fell to less than 0.4 meq/L in serum and 0.1 meq/L in cerebrospinal fluid. The lack of parallel change in serum concentrations and coma probably reflects the lag time in equilibration between lithium concentrations in serum and brain.

The effect of lithium carbonate on lymphocyte, granulocyte, and platelet function

Lithium affects an increase in granulocyte counts in humans and has been promoted in the treatment of granulocytopenia and as adjuvant cancer chemotherapy to reduce the incidence of bacterial infections. In this study, eight healthy volunteers were studied by means of a panel of quantitative and cellular function tests before and after a seven-day course of lithium carbonate. Granulocyte, lymphocyte, and platelet function was assessed by the test panel. This panel included T cell and B cell enumeration, lymphocyte transformation to a number of mitogens and antigens, phagocytic and bactericidal activities of peripheral leukocytes, nitroblue tetrazolium (NBT) reduction, chemotaxis, chemiliminescence, platelet aggregation studies, and Ivy bleeding time. The was a significant reduction in bactericidal capacity (p less than 0.005) and a significant reduction in lymphocyte response to PPD (p less than 0.01). Although lithium increase the granulocyte count, the reduction in bactericidal capacity of granulocytes may reduce the beneficial effect of the granulocytosis. Prospective clinical studies are indicated to assess the clinical efficacy of the drug.