The pharmacokinetics of oral carbamazepine in rats dosed using an automated drug delivery system.

OBJECTIVE: Pharmacokinetics (PK) of antiseizure drugs differ considerably between rats and humans. Rodents require larger and more frequent doses to maintain therapeutic drug levels. This study uses the antiseizure drug (ASD) carbamazepine (CBZ) to validate the application of a previously described automated drug delivery system for delivering chronic oral medication to rats. METHODS: Treatment-naive, male Sprague-Dawley rats were treated with oral CBZ, 75 mg/kg every 6 hours for 10 days, via the automated feeder. Blood samples were collected on day 0 (acute), day 2 (steady-state), and day 9 (chronic) and used to measure plasma CBZ and carbamazepine-10,11-epoxide (CBZ-E) concentrations via high-performance liquid chromatography. The PK of CBZ and CBZ-E were modeled using Monolix v2018R1. The acute and chronic tolerability of CBZ was evaluated using the open field test. RESULTS: CBZ and CBZ-E concentrations were best described by a one-compartment parent-metabolite model with first-order absorption and elimination kinetics. Observed and predicted CBZ concentrations were maintained within the therapeutic window (4-12 µg/mL) for the duration of the study. There was no change in open-field test activity following acute or chronic oral dosing of 75 mg/kg CBZ compared to a pretreatment baseline (P > 0.4). SIGNIFICANCE: Oral administration of CBZ dosed q.i.d. in rats using an automated drug delivery system results in therapeutic concentrations of CBZ and its active metabolite. This study represents the first PK validation for this previously described preclinical drug delivery system.

Correction of medication nonadherence results in better seizure outcomes than dose escalation in a novel preclinical epilepsy model of adherence.

OBJECTIVE: Medication nonadherence directly contributes to poor seizure control. A lack of emphasis on correcting poor adherence and failures in patient adherence can result in unwarranted alterations to a patient's drug regimen. We have modeled nonadherent patients in an animal model of epilepsy to study how alterations to pharmacotherapy, made without consideration of a patient's adherence, result in changes to seizure control. METHODS: Newly diagnosed rats with epilepsy were treated with carbamazepine (CBZ) during a 4-week baseline period to establish their baseline seizure rate in the presence of 50% adherence. Next, animals were randomized to one of three treatment interventions and monitored for 6 weeks. Groups included: (1) no change in therapy-rats continued the 50% adherent paradigm; (2) dose escalation-the dose of CBZ was doubled, and the 50% adherent paradigm continued; and (3) nonadherence corrected-rats continued the initial dose of CBZ, but the adherence rate was adjusted to 100% (ie, fully adherent). RESULTS: The rats in the no change in therapy arm displayed a 61% increase in seizure burden over the 6-week intervention phase. Similarly, rats in the dose escalation arm had a 66% worsening of their daily seizure burden. In contrast, rats in the nonadherence corrected arm displayed a 33% reduction in their daily seizure burden; a significant improvement when compared to the normalized seizure burden scores of rats in the other two treatment arms (P < 0.01). SIGNIFICANCE: We found that failure to correct medication nonadherence resulted in an increase in daily seizure burden in rats, even following dose escalation. In the presence of nonadherence, dose escalation worsened seizure control. In contrast, correcting nonadherence alone resulted in improved seizure control. These findings suggest that improving adherence should be prioritized over dose escalation in the clinical management of uncontrolled epilepsy.

Physiological relevance of LL-37 induced bladder inflammation and mast cells.

PURPOSE: We established the physiological relevance of LL-37 induced bladder inflammation. We hypothesized that 1) human urinary LL-37 is increased in pediatric patients with spina bifida, 2) LL-37 induced inflammation occurs in our mouse model via urothelial binding and is dose dependent and 3) LL-37 induced inflammation involves mast cells. MATERIALS AND METHODS: To test our first hypothesis, we obtained urine samples from 56 pediatric patients with spina bifida and 22 normal patients. LL-37 was measured by enzyme-linked immunosorbent assay. Our second hypothesis was tested in C57Bl/6 mice challenged with 7 LL-37 concentrations intravesically for 1 hour. At 24 hours tissues were examined histologically and myeloperoxidase assay was done to quantitate inflammation. In separate experiments fluorescent LL-37 was instilled and tissues were obtained immediately (time = 0) and at 24 hours (time = 24). To test our final hypothesis, we performed immunohistochemistry for mast cell tryptase and evaluated 5 high power fields per bladder to determine the mean number of mast cells per mm(2). RESULTS: Urinary LL-37 was 89-fold higher in patients with spina bifida. Mouse LL-37 dose escalation experiments revealed increased inflammation at higher LL-37 concentrations. Fluorescent LL-37 demonstrated global urothelial binding at time = 0 but was not visible at time = 24. Immunohistochemistry for tryptase revealed mast cell infiltration in all tissue layers. At higher concentrations the LL-37 challenge led to significantly greater mast cell infiltration. CONCLUSIONS: Urinary LL-37 was significantly increased in pediatric patients with spina bifida. To our knowledge we report for the first time that LL-37 can elicit profound, dose dependent bladder inflammation involving the urothelium. Finally, inflammation propagation involves mast cells.