A new C-Peptide correction model used to assess bioavailability of regular human insulin.

The clinical assessment of new formulations of human insulin is problematic due to the inability to distinguish between endogenous insulin and exogenously administered insulin. The usual methods to surmount the problem of distinguishing between endogenous and exogenous human insulin include evaluation in subjects with no or little endogenous insulin, hyper-insulinemic clamp studies or the administration of somatostatin to suppress endogenous insulin secretion. All of these methods have significant drawbacks. This paper describes a method for C-Peptide correction based upon a mixed effects linear regression of multiple time point sampling of C-Peptide and insulin. This model was able to describe each individual's insulin to C-Peptide relationship using the data from four different phase I clinical trials involving both subjects with and without type 2 diabetes in which insulin and C-Peptide were measured. These studies used hyper-insulinemic euglycemic clamps or meal challenges and subjects received insulin or Glucagon-like peptide 1 (GLP-1). It was possible to determine the exogenously administered insulin concentration from the measured total insulin concentration. A simple statistical technique can be used to determine each individual's insulin to C-Peptide relationship to estimate exogenous and endogenous insulin following the administration of regular human insulin. This technique will simplify the assessment of new formulations of human insulin.

Orally administered unfractionated heparin with carrier agent is therapeutic for deep venous thrombosis.

BACKGROUND: Orally administered heparin (OHEP) is unreliable because of poor absorption. Sodium N-(8[2-hydroxybenzoyl]amino) caprylate (SNAC) is an amido acid that facilitates the gastrointestinal absorption of heparin. We evaluated the effectiveness of OHEP combined with SNAC (OHEP/SNAC) in the treatment of deep-vein thrombosis (DVT). METHODS AND RESULTS: An internal jugular DVT was produced in 54 male Sprague-Dawley rats. Animals were assigned to 6 different groups for 7 days of treatment: untreated control, subcutaneous heparin (SC HEP) (300 U/kg SC TID), SNAC only (300 mg/kg PO TID), OHEP only (30 mg/kg PO TID), low-molecular-weight heparin (LMWH) (enoxaparin 5 mg/kg SC QD), and OHEP/SNAC (30 mg/kg:300 mg/kg PO TID). The activated partial thromboplastin time (aPTT) and anti-factor X (anti-Xa) levels were measured. The incidence of residual DVT after 1 week of treatment was 100% (9 of 9) in the control group versus 10% (1 of 10) in the OHEP/SNAC and 10% (1 of 10) in the LMWH groups (P<0.001). There was also a significant reduction in clot weights between these groups. Compared with controls, there were no significant differences in the residual DVT in the SNAC-only (6 of 6), OHEP-only (9 of 9), or SC HEP (8 of 10) groups. Combination OHEP/SNAC was as effective in the resolution of the clot and reducing clot weight as LMWH. The aPTT levels in the OHEP/SNAC group peaked at 30 minutes and were significantly higher than in all other groups (P<0.01). Anti-Xa levels were elevated at 15 minutes after dosing in the OHEP/SNAC group and remained significantly elevated at 4 hours (P<0.001). CONCLUSIONS: OHEP combined with a novel carrier agent (SNAC) successfully treated DVT in this rat model.

Oral heparin administration with a novel drug delivery agent (SNAC) in healthy volunteers and patients undergoing elective total hip arthroplasty.

BACKGROUND: Unfractionated heparin (UFH) is safe and effective for thromboprophylaxis, but its use is limited to parenteral administration. A novel drug delivery agent (SNAC) has been developed to accomplish the oral delivery of heparin. OBJECTIVE: This report describes the foundation for dose selection and use of oral heparin/SNAC in patients undergoing elective total hip arthroplasty (THA). PATIENTS AND METHODS: To develop a treatment regimen for clinical study, a multiple dose Phase I pharmacokinetic (PK) study in healthy volunteers compared oral heparin/SNAC (90 000 U heparin) with subcutaneous UFH (5000 U). On this basis, we carried out a double-blind, randomized, multicenter study comparing subcutaneous UFH (5000 U) with oral heparin/SNAC at either 60 000 or 90 000 U heparin in 123 patients undergoing elective THA. Patients received, postoperatively, one of the three treatments every 8 h for a total of 12 doses and were followed for 35 days post surgery. RESULTS: In the Phase I study, anti-factor Xa activity peaked at 45-60 min following oral heparin/SNAC, returning to baseline at 4 h. RESULTS of the randomized trial in THA patients showed that venous thromboembolic events (n = 6), major bleeding events (n = 5) and need for transfusion (n = 23) were distributed evenly among the three treatment groups, UFH and both doses of oral heparin/SNAC. CONCLUSION: This is the first demonstration that oral heparin/SNAC can be safely delivered to the postoperative THA patient, and provides the basis for a larger clinical trial to assess the prophylactic efficacy of heparin/SNAC.

Studies directed at the use of a parallel synthesis matrix to increase throughput in an in vivo assay.

Heparin is the anticoagulant of choice for hospitalized patients, but it is dosed only by injection because it is not absorbed following oral administration. We have discovered and prepared compounds (delivery agents) that facilitate the gastrointestinal absorption of heparin in rats, monkeys, and humans when given orally. We are currently developing a parallel synthesis approach to increase our delivery agent screening throughput in vivo. This approach has been used to produce micromolar quantities of compounds for testing in rats in a 5 x 5 parallel synthesis array. Using an amine benzoylation reaction sequence, 10 mixtures were prepared. These mixtures contained equal weight quantities of five N-substituted, non-alpha, amino acid delivery agents. Each of these mixtures was orally administered to rats in combination with heparin, and plasma clotting times (APTT) were measured to determine activity. Deconvolution of the data accurately identified the most active individual components. Independent synthesis of these compounds verified their activity. This parallel synthesis approach is an effective tool for the screening of oral heparin delivery agents and has increased screening throughput significantly.

4-[4-[(2-Hydroxybenzoyl)amino]phenyl]butyric acid as a novel oral delivery agent for recombinant human growth hormone.

A series of N-acetylated, non-alpha, aromatic amino acids was prepared and shown to promote the absorption of recombinant human growth hormone (rhGH) from the gastrointestinal tract. Seventy compounds in this family were tested in vivo in rats. Of the compounds tested, 4-[4-[(2-hydroxybenzoyl)amino]phenyl]butyric acid was identified as a preclinical candidate and was used to demonstrate the oral delivery of rhGH in primates. A significant positive correlation was found between the relative log k' of the delivery agents, as determined by HPLC on an immobilized artificial membrane (IAM) column, and serum rhGH concentrations following oral or colonic dosing in rats. Structure-activity relationships have also been developed on the basis of electronic effects and hydrogen-bonding characteristics of the aromatic amide substituents.

Synthesis and evaluation of compounds that facilitate the gastrointestinal absorption of heparin.

A family of novel compounds (delivery agents) that promote the gastrointestinal absorption of USP heparin in rats and primates has been discovered. The delivery agents in combination with heparin were administered either orally or intracolonically in an aqueous propylene glycol solution and caused dramatic increases in both plasma heparin concentrations (anti-Factor Xa) and clotting times (APTT). Using one of the most effective delivery agents in this series, an estimated relative bioavailability of 8% can be achieved following oral administration to cynomolgus monkeys. To establish a correlation between the in vivo data and an in vitro parameter, immobilized artificial membrane (IAM) chromatography was performed. Log relative k' values were correlated to the efficiency of oral heparin delivery.

Acylated non-alpha-amino acids as novel agents for the oral delivery of heparin sodium, USP.

Ten N-acylated, non-alpha-amino acids have been prepared as oral delivery agents and used to demonstrate the oral delivery of heparin in vivo in rats and primates. Following the oral administration of solutions containing a combination of heparin and a delivery agent to rats or primates, significant plasma heparin concentrations were evidenced by APTT and anti-Factor Xa assays. The estimated pharmacodynamic equivalence for an oral dosing solution containing heparin and a delivery agent is 39% in primates. In vitro experiments based on heparin affinity chromatography or heparin/methylene blue complexation were also performed to begin investigation of the mechanism by which these compounds facilitate heparin oral delivery. Results of in vitro studies suggest that absorption of the drug across the gastrointestinal membrane is the result of a non-covalent interaction between heparin and the delivery agent.

Orally administered heparin for preventing deep venous thrombosis.

BACKGROUND: Sodium N-(8-[2-hydroxybenzoyl] amino) caprylate (SNAC) is an acetylated amino acid molecule that facilitates the gastrointestinal absorption of heparin. This study was undertaken to evaluate the efficacy of orally administered combination SNAC:heparin in preventing deep venous thrombosis in a standard rat model. METHODS: Forty-four adult male Sprague-Dawley rats were randomly divided into five groups: group I control, group II SNAC, group III oral heparin, group IV combination SNAC:heparin, and group V intravenous heparin. Thirty minutes after drug administration, the internal jugular vein was bathed in a sclerosant mixture for 2 minutes and reexplored at 120 minutes. Activated partial thromboplastin times (aPTT) were measured in 30 rats equally divided into three groups: group I SNAC, group II oral heparin, and group III combination SNAC:heparin. Forty-five minutes posttreatment, blood was obtained for aPTT levels. RESULTS: The incidence of deep venous thrombosis in the control group was 89% (8 of 9) versus 25% (2 of 8) in the combination SNAC:heparin group (p < 0.01). There was also a significant reduction in clot weight among groups. Combination SNAC:heparin significantly increased aPTT levels compared with SNAC or oral heparin alone. CONCLUSION: In a rat model of venous thrombosis, combination of orally administered heparin:SNAC elevated aPTT levels and significantly reduced the formation of deep venous thrombosis.

Stability study of drug-loaded proteinoid microsphere formulations during freeze-drying.

Drug-loaded proteinoid microspheres were freeze-dried to facilitate shipping and handling and to enable long term storage. Heparin was chosen as the model drug in developing the optimum lyophilization process. The factors influencing the integrity of either heparin-loaded or unloaded ('empty') proteinoid microspheres during freeze-drying were determined, with emphasis on: selecting an optimum freezing and resuspending temperature; choosing an appropriate cryoprotectant and its optimum concentration in the formulation; and, designing a suitable method for formulating the microspheres. Freezing at/below -70 degrees C was found to minimize damage to the microspheres. Addition of sugars, such as trehalose and lactose, as cryoprotectants, further increased the stability of the heparin-loaded microspheres during freeze-drying. The optimum trehalose or lactose concentrations were determined to be 5% (w/v). Using the optimumized lyophilization process described in this manuscript, microspheres remained intact during freeze-drying. The freeze-dried microspheres were stable for at least three months post-lyophilization.

Aggressive osteoblastoma of the mandible closely simulating calcifying epithelial odontogenic tumor. Report of two cases with unusual histopathologic findings.

Aggressive osteoblastoma is a rare bone-forming neoplasm composed of prominent epithelioid cells that demonstrate locally invasive growth with a high rate of recurrence but no metastatic potential. Clinical, radiographic and pathologic features of mandibular aggressive osteoblastoma in a 21-year-old African-American male and a 12-year-old Caucasian female are presented. Both tumors were resected with wide surgical margins and neither patient had adjuvant radiation or chemotherapy. The patients showed no evidence of local recurrence or distant spread either clinically or radiographically after two years of follow-up. These tumors were composed of solid sheets of pleomorphic epithelioid cells, eosinophilic amorphous osteoid with foci of calcification, which closely simulated amyloid. Differentiation of this tumor from histologically similar calcifying epithelial odontogenic tumor and low-grade osteosarcoma proved difficult. Immunohistochemical study with osteocalcin confirmed the osteoblastic nature of these epithelioid cells.

Prepubertal oral pemphigus vulgaris.

Although rare, oral pemphigus vulgaris must be considered in those patients who have a prolonged history of oral lesions. The fact that chronic oral lesions characteristically precede skin changes in pemphigus emphasizes the importance of this disease to the dental profession. Patients with long-term and recurrent vesiculoulcerative oral lesions should undergo biopsy examination to establish the diagnosis. The dentist and the physician must collaborate to establish an appropriate diagnostic and therapeutic plan for the management of these patients.

Recurrent aphthous stomatitis: primary care management.

Recurrent aphthous stomatitis (RAS), often referred to as canker sore, is a chronic inflammatory disease. Frequently seen in the primary care setting, RAS affects over 50% of the population and may be observed in an otherwise apparently healthy individual. An unknown pathogenesis and absence of curative treatment make RAS a challenge to manage. Treating RAS should be patient specific and focus on reduction of pain and lesions. An awareness of literature suggesting etiologies, precipitating, and predisposing factors can assist the practitioner and patient in controlling RAS episodes. Contained in this review is a suggested course of management for patients with RAS, including present recommendations for pharmacological interventions.

Recurrent aphthous stomatitis vs. recurrent herpes: do you know the difference?

Herpetic and aphthous ulcers can be easily separated from each other on a clinical basis. Most patients who suffer from recurrent oral ulcers, suffer from one of the three forms of aphthous stomatitis that can be effectively treated. Unfortunately, the dental and medical professions are uninformed about recurrent oral ulcer etiology and proper therapies. The result is that large numbers of patients are repeatedly told there is no adequate treatment or control for their condition when in most cases that is not true. We should not permit that trend to continue. Our patients deserve better treatment from a more informed profession.

Chievitz's organ: a potential pitfall in oral cancer diagnosis.

It has been reported that epithelial nests associated with sensory nerve fibers may simulate perineural invasion and pose a potential diagnostic problem for surgical pathologists working on frozen tissue specimens from patients with oral cancer. The epithelial structures are not neoplastic, and no known pathologic condition has been associated with them. They are believed to be those structures described scantily in the English literature as Chievitz's organ. The fact that the epithelial nests lie near the plane of injection for the inferior alveolar nerve should be of special interest to dentists, especially oral surgeons and pathologists. Controversy exists as to the exact nature of Chievitz's organ, but the potential hazard of misdiagnosis exists nonetheless. This study of cadaver and autopsy material reaffirms the existence of the epithelial rests and outlines a simple technique for locating them.

The oral hair: an extremely rare phenomenon.

A proven case of true hair occurring naturally in the mouth has been reported only once previously. A second case of this rare anomaly is reported here. In this case a single hair was found at the base of the attached gingiva in the mandibular cuspid region of a 45-year old white man.