Assessing the Impact of Tissue Target Concentration Data on Uncertainty in In Vivo Target Coverage Predictions.

Understanding pharmacological target coverage is fundamental in drug discovery and development as it helps establish a sequence of research activities, from laboratory objectives to clinical doses. To this end, we evaluated the impact of tissue target concentration data on the level of confidence in tissue coverage predictions using a site of action (SoA) model for antibodies. By fitting the model to increasing amounts of synthetic tissue data and comparing the uncertainty in SoA coverage predictions, we confirmed that, in general, uncertainty decreases with longitudinal tissue data. Furthermore, a global sensitivity analysis showed that coverage is sensitive to experimentally identifiable parameters, such as baseline target concentration in plasma and target turnover half-life and fixing them reduces uncertainty in coverage predictions. Overall, our computational analysis indicates that measurement of baseline tissue target concentration reduces the uncertainty in coverage predictions and identifies target-related parameters that greatly impact the confidence in coverage predictions.

Pharmacokinetics and anti-inflammatory pharmacodynamics of prednisolone in cynomolgus monkey.

The purpose was to investigate whether the pharmacokinetics and pharmacodynamics of prednisolone in the non-human primate was an appropriate surrogate for man. After single intravenous doses of 0.03, 0.3, and 3 mg kg(-1), prednisolone demonstrated a dose-dependent clearance and volume of distribution. When corrected for concentration-dependent protein binding, the free clearance was linear at the tested dose levels. The protein binding-corrected volume of distribution was similar across doses. The serum half-life was estimated as being between 2 and 4 h. Prednisolone exhibits near complete inhibition of the cytokines TNF-alpha, IL-1beta, IL-6 and IL-8 with very similar IC50 estimates from 0.09 to 0.16 microg ml(-1) (from 0.24 to 0.44 microM). The monkey demonstrated a similar pharmacokinetics-pharmacodynamics profile of prednisolone when compared with man (from the literature).

Simultaneous high-performance liquid chromatographic determination of Cedrus deodara active constituents and their pharmacokinetic profile in mice.

A specific and sensitive high-performance liquid chromatographic (HPLC) method with photodiode-array (PDA) ultraviolet detection was developed for the simultaneous determination of three bioactive constituents of Cedrus deodara namely wikstromol, matairesinol and dibenzylbutyrolactol in mouse plasma. In solid-phase extraction (SPE) these constituents were successfully separated using a C18 column by isocratic elution using acetonitrile:water containing hexanesulphonic acid, 32:68 (v/v). The flow rate was set at 1ml/min and detector wavelength at 225nm. Good linearity (r2>0.999) was observed over the studied range of 0.015-5.0microg/ml for wikstromol and 0.030-5.0microg/ml for matairesinol and dibenzylbutyrolactol. The CV values of intra-day precision for wikstromol, matairesinol and dibenzylbutyrolactol were in between 1.8-6.9, 1.7-4.9 and 1.6-4.2% and values of inter-day precision were in between 10.4-12.2, 9.7-11 and 10-11.2%, respectively. The extraction recoveries at low to high concentration were greater than 98, 83 and 87% for each analyte, respectively. The LOQ for wikstromol was 0.015microg/ml and for both matairesinol and dibenzylbutyrolactol it was 0.030microg/ml. The developed method was used to determine the pharmacokinetics of the three analytes in mice after intraperitoneal administration of CD-3.

A 5-year course of predominantly obsessive vs. mixed subtypes of obsessive-compulsive disorder.

BACKGROUND: Obsessive-compulsive disorder (OCD) is considered a heterogeneous disorder. One of the traditional approaches to subtype OCD is based on the predominance of obsessions, compulsions or both. Some studies suggest that the "predominantly obsessive" subtype of OCD may have poor outcome, whereas few other studies suggest that "mixed" OCD is associated with poor outcome. Therefore, it is not clear if the long-term course of "predominantly obsessive" subjects is different from those with "mixed" OCD. In the establishment of diagnostic validity of psychiatric conditions, differential course is an important validating factor. AIM: This study compares the 5-6 year course of the "predominantly obsessive" subtype with that of the "mixed" subtype of OCD with the objective of determining if the course of OCD differs according to subtypes and whether course could be a validating factor for subtyping OCD based on predominance of obsessions, compulsions or both. SETTING AND DESIGN: Tertiary hospital, institutional setting. The study has a retrospective cohort design. MATERIALS AND METHODS: Fifty-four subjects with "predominantly obsessions" and an equal number of the "mixed" subtype of OCD were recruited from the database of a specialty OCD clinic of a major psychiatric hospital. They were followed up after 5-6 years. The Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) checklist and severity rating scale was used for assessing OCD. The course of OCD was determined according to predefined criteria. STATISTICS: The Chi-square/Fisher's exact test and the independent samples "t" test were used to compare categorical and continuous variables, respectively. Correlations were tested using the Pearson's correlation analysis. RESULTS: Thirty-eight "predominantly obsessive" (70%) and 39 "mixed" (72%) OCD subjects could be traced and evaluated. The course of illness was similar in the two subtypes. A majority of the sample (72%) did not have clinical OCD at follow-up. CONCLUSIONS: "Predominantly obsessive" subjects have a course similar to those with "mixed" OCD. Clinically, it is reassuring to know that obsessive subjects do not have an unfavorable course as was suggested by some previous studies. In this sample, course did not validate the subtyping method employed, but it would be premature to conclude that the subtyping method employed is incorrect based on the course alone. Prospective study of the course in larger samples and neurobiological and family-genetic data may help further validation.

Comorbidity of anxiety disorders in patients with remitted bipolar disorder.

Comorbidity between bipolar disorder and anxiety disorders has attracted considerable attention in recent years. However, a majority of the earlier studies examined anxiety disorders in acutely ill patients resulting in a possible confounding effect of the affective episodes. This study examines the prevalence of anxiety disorders in remitted bipolar subjects recruited from a psychiatric hospital in India and their effect on the severity of bipolar illness. A total of eighty remitted DSM-IV adult bipolar subjects and 50 non-psychiatric controls were recruited over a 10-month period. They were evaluated using a structured interview and various scales. The effect of anxiety disorders on bipolar severity was analyzed using multiple regression analyses. Anxiety disorders were highly prevalent in bipolar subjects compared to controls (49 [61%] vs. 7 [14%], chi(2) = 28.01, P < 0.001). Commonest lifetime anxiety disorder was obsessive-compulsive disorder (35%). Lifetime anxiety disorder had significant effect on all four indices of severity of illness, that included (1) percentage of time spent in episodes (Beta = 18.67, SE = 5.11, P < 0.001), (2) maximum period of continuous euthymia in the preceding 2 years (Beta = -5.26, SE = 1.71, P = 0.003), (3) presence of psychosis (Beta = 3.22, SE = 1.02, P = 0.002), and 4) response to mood stabilizers (Beta = -2.11, SE = 0.76, P = 0.006). The findings of this study confirm previous observations of the high prevalence and negative impact of comorbid anxiety disorders in bipolar disorder and also demonstrate that the findings are similar in culturally diverse settings. Future studies should systematically examine the various treatment options for anxiety disorders in bipolar patients. It is also necessary to examine the neurobiological and family/genetic correlates of anxious bipolar subjects to validate if they are a subgroup of bipolar disorders.

Biodistribution of 4-[(14)C]cholesterol-AmBisome following a single intravenous administration to rats.

A biodistribution study of 4-[(14)C]cholesterol-AmBisome; a unilamellar liposomal preparation of amphotericin B was conducted to support a radiolabeled human study. The radioactive plasma concentration profile (as measured in microg-Eq/ml of cholesterol) was best fit to a sum of three exponentials that yielded alpha-, beta-, and gamma-half-life estimates of 3.0 +/- 0.3, 11.8 +/- 3.7, and 113.4 +/- 32.4 h, respectively. Clearance and the steady state volume of distribution were 4.9 +/- 0.2 ml/h/kg and 341 ml/kg. Recovery data collected up through 96 h demonstrated mass balance and indicated that although the elimination profile in both urine and feces were incomplete, the dominant route of elimination (<2% in urine versus 33% in feces) was feces, presumably via biliary excretion of intact liposome and/or cholesterol. The liver, spleen, and lungs, organs of the reticuloendothelial system known for their rapid uptake of liposomes, presented with the highest levels of radioactivity. Levels in the kidney were 15% of that found in the liver and lungs.

Pharmacokinetics of a potential human cytomegalovirus therapeutic, a phosphorothioate oligonucleotide, after intravitreal injection in the rabbit.

The disposition of ISIS 2922, a phosphorothioate oligonucleotide for treatment of cytomegalovirus associated retinitis, was evaluated in rabbits. Vitreous humor and retina samples were collected from rabbits that received a single intravitreal injection of 66 microg [14C]-labeled ISIS 2922 and were analyzed using anion exchange HPLC. Four hr postdosing, the concentration of ISIS 2922 in vitreous humor was 3.3 microM. The elimination of ISIS 2922 from the vitreous humor exhibited first-order kinetics with a t1/2 of 62 hr. By 10 days postdosing, the mean concentration of ISIS 2922 in rabbit vitreous humor had decreased to 0.17 microM, which represented 22% of the total radioactivity remaining in the vitreous. The remaining 78% coeluted on anion exchange HPLC with shorter oligonucleotides. In retina, ISIS 2922 accumulated over the first 5 days postdosing, reaching a maximum concentration of 3.5 microM, and then declined thereafter with an estimated t1/2 of 79 hr. By 10 days postdosing when only 24% of the total radioactivity in the retina was parent compound, the concentration of ISIS 2922 remained at 1.6 microM, which was 10 times higher than the concentration in the vitreous humor. Whereas the elimination of full-length ISIS 2922 and total radioactivity from the vitreous humor occurred at nearly equal rates, ISIS 2922 disappeared more rapidly than did total radioactivity from the retina, suggesting a greater role for metabolism in the clearance process from retina than the vitreous. Alternatively, the results are consistent with metabolites being cleared from the vitreous at approximately the same rate as parent compound while in the retina metabolites may be cleared more slowly. The data were analyzed with a user-defined pharmacokinetic model, which was then used to predict the potential for accumulation of ISIS 2922 during clinical dosing.

Evaluation of the systemic toxicity and pharmacokinetics of the immunoconjugate anti-B4-blocked ricin in non-human primates. Delivered by multiple bolus injections and by continuous infusion.

The systemic toxicity of an immunoconjugate of blocked ricin and the anti-CD19 monoclonal antibody, anti-B4, was studied in cynomolgus monkeys to evaluate its safety for use in humans. Anti-B4-blocked Ricin (Anti-B4-bR) is a highly cytotoxic immunoconjugate which can kill up to 5 logs of antigen positive target cells at concentrations easily achievable in blood. Subacute toxicity studies with Anti-B4-bR were performed in 20 cynomolgus monkeys and 4 rhesus monkeys, which, unlike humans, do not express the CD19 epitope recognized by the anti-B4 antibody on their B-lymphocytes. Anti-B4-bR was administered to cynomolgus monkeys by 5 daily intravenous bolus injections of 10 or 100 micrograms/kg/day, and non-conjugated blocked ricin was administered by 5 daily intravenous bolus injections of 30 micrograms/kg/day. Total doses of the conjugate of 200, 500, 1000 or 1500 micrograms/kg were also delivered to rhesus monkeys by continuous intravenous infusion over seven days. The clinical signs of toxicity, clinical pathology parameters, and gross and microscopic tissue changes associated with Anti-B4-bR were minimal to moderate where present, and primarily hepatic. In monkeys treated with 5 x 10 micrograms/kg of Anti-B4-bR, lesions were noticeable on day 7 after the start of the treatment but were less severe or absent on day 14, suggesting that the toxic effects were reversible. Clearance of the conjugate from the serum after bolus injections of Anti-B4-bR was evaluated by ELISA and demonstrated an initial t 1/2(alpha) of 1.4-2.0 h and a secondary t 1/2(beta) of about 14 h. Serum concentrations of Anti-B4-bR were about 10-20-fold lower at 24 h as compared to 1 h after each of the 5 bolus injections in monkeys. Continuous infusion of Anti-B4-bR in primates achieved plateau levels of the immunotoxin in blood for almost the entire duration of the infusion. The therapeutic utility of the Anti-B4-bR is currently being evaluated in patients with B-cell malignancies.