Structure-Activity Relationships of a Series of Echinocandins and the Discovery of CD101, a Highly Stable and Soluble Echinocandin with Distinctive Pharmacokinetic Properties.

Echinocandins are a first-line therapy for candidemia and invasive candidiasis. They are generally safe with few drug interactions, but the stability and pharmacokinetic properties of currently approved echinocandins are such that each was developed for daily intravenous infusion. We sought to discover a novel echinocandin with properties that would enable more flexible dosing regimens, alternate routes of delivery, and expanded utility. Derivatives of known echinocandin scaffolds were generated, and an iterative process of design and screening led to the discovery of CD101, a novel echinocandin that has since demonstrated improved chemical stability and pharmacokinetics. Here, we report the structure-activity relationships (including preclinical efficacy and pharmacokinetic data) for the series of echinocandin analogs from which CD101 was selected. In a mouse model of disseminated candidiasis, the test compounds displayed clear dose responses and were generally associated with lower fungal burdens than that of anidulafungin. Single-dose pharmacokinetic studies in beagle dogs revealed a wide disparity in the half-lives and volumes of distribution, with one compound (now known as CD101) displaying a half-life that is nearly 5-fold longer than that of anidulafungin (53.1 h versus 11.6 h, respectively). In vitro activity data against panels of Candida spp. and Aspergillus spp. demonstrated that CD101 behaved similarly to approved echinocandins in terms of potency and spectrum of activity, suggesting that the improved efficacy observed in vivo for CD101 is a result of features beyond the antifungal potency inherent to the molecule. Factors that potentially contribute to the improved in vivo efficacy of CD101 are discussed.

Chronic actions of a novel oral B-type natriuretic peptide conjugate in normal dogs and acute actions in angiotensin II-mediated hypertension.

BACKGROUND: We previously reported the feasibility of an acute, orally delivered, newly developed, conjugated form of human B-type natriuretic peptide (hBNP) in normal animals. The objective of the present study was to extend our findings and to define the chronic actions of an advanced oral conjugated hBNP (hBNP-054) administered for 6 days on sodium excretion and blood pressure. We also sought to establish the ability of this new conjugate to acutely activate cGMP and to reduce blood pressure in an experimental model of angiotensin II (ANG II) -mediated hypertension. METHODS AND RESULTS: First, we developed additional novel conjugated forms of oral hBNP that were superior to our previously reported hBNP-021 in reducing blood pressure in 6 normal dogs. We then tested the new conjugate, hBNP-054, chronically in 2 normal dogs to assess its biological actions as a blood pressure-lowering agent and as a natriuretic factor. Second, we investigated the effects of acute oral hBNP-054 or vehicle in 6 dogs that received continuous infusion of ANG II to induce hypertension. After baseline determination of mean blood pressure (MAP) and blood collection for plasma hBNP and cGMP, all dogs received continuous ANG II infusion (20 ng . kg(-1) . min(-1), 1 mL/min) for 4 hours. After 30 minutes of ANG II, dogs received oral hBNP-054 (400 microg/kg) or vehicle in a random crossover fashion with a 1-week interval between dosing. Blood sampling and MAP measurements were repeated 30 minutes after ANG II administration and 10, 30, 60, 120, 180, and 240 minutes after oral administration of hBNP-054 or vehicle. In the chronic study in normal dogs, oral hBNP-054 effectively reduced MAP for 6 days and induced a significant increase in 24-hour sodium excretion. hBNP was not present in the plasma at baseline in any dogs, and it was not detected at any time in the vehicle group. However, hBNP was detected throughout the duration of the study after oral hBNP-054, with a peak concentration at 30 minutes of 1060+/-818 pg/mL. In the acute study, after ANG II administration, plasma cGMP was not activated after vehicle, whereas it was significantly increased after oral hBNP-054 (P=0.01 between the 2 groups). Importantly, MAP was significantly increased after ANG II throughout the acute study protocol. However, although no changes occurred in MAP after vehicle administration, oral hBNP-054 reduced MAP for >2 hours (from 138+/-1 mm Hg after ANG II to 124+/-2 mm Hg at 30 minutes, 124+/-2 mm Hg at 1 hour, and 130+/-5 mm Hg at 2 hours after oral hBNP-054; P<0.001). CONCLUSIONS: This study reports for the first time that a novel conjugated oral hBNP possesses blood pressure-lowering and natriuretic actions over a 6-day period in normal dogs. Furthermore, hBNP-054 activates cGMP and reduces MAP in a model of acute hypertension. These findings advance the concept that orally administered chronic BNP is a potential therapeutic strategy for cardiovascular diseases such as hypertension.

CD101, a novel echinocandin with exceptional stability properties and enhanced aqueous solubility.

The echinocandins are an important class of antifungal agents. However, instability and, in some cases, lack of solubility have restricted their use to situations in which daily infusions are acceptable. CD101 is a novel echinocandin in development for topical and weekly i.v. administration that exhibits prolonged stability in plasma and aqueous solutions up to 40 °C. After incubation for 44 h in rat, dog, monkey and human plasma at 37 °C, the percent of CD101 remaining (91%, 79%, 94% and 93%, respectively) was consistently greater than that of anidulafungin (7%, 15%, 14% and 7%, respectively). Similarly, after incubation in phosphate-buffered saline at 37 °C, the CD101 remaining (96%) was greater than that of anidulafungin (42%). CD101 exhibited <2% degradation after long-term storage at 40 °C as a lyophilized powder (9 months) and at room temperature in 5% dextrose (15 months), 0.9% saline (12 months) and sterile water (18 months). Degradation was <7% at 40 °C in acetate and lactate buffers (6 to 9 months at pH 4.5-5.5). The chemical stability and solubility of CD101 contribute to dosing, pharmacokinetic, formulation and safety advantages over other echinocandins and should expand utility beyond daily i.v.

Oral human brain natriuretic peptide activates cyclic guanosine 3',5'-monophosphate and decreases mean arterial pressure.

BACKGROUND: The objective of this study was to address the feasibility and the biological activity of orally administered human brain natriuretic peptide (hBNP). Proprietary technology has been developed in which short, amphiphilic oligomers are covalently attached to peptides. The conjugated peptides are intended to have an improved pharmacokinetic profile and to enable oral administration. We hypothesized that novel oral conjugated hBNP (CONJ-hBNP) increases plasma hBNP, activates cGMP, and reduces mean arterial pressure (MAP). METHODS AND RESULTS: This randomized crossover-designed study tested the biological activity of oral CONJ-hBNP compared with oral native hBNP in normal conscious dogs. Measurements of MAP, plasma hBNP, and cGMP were made at baseline (BL) and repeated at 10, 30, 60, 120, 180, and 240 minutes after oral administration. Plasma hBNP was not detectable in dogs at BL. Plasma hBNP was detected after native hBNP and CONJ-HBNP administration. However, plasma hBNP concentration was significantly higher after CONJ-hBNP than after native hBNP administration (P=0.0374 between groups). Plasma cGMP increased after CONJ-hBNP for 60 minutes (from 10.8+/-3 to 36.8+/-26 pmol/mL; P<0.05), whereas it did not change after native hBNP (P=0.001 between groups). MAP decreased at 10 minutes and remained decreased for 60 minutes after CONJ-hBNP (from 113+/-8 to 101+/-12 mm Hg after 10 minutes to 97.5+/-10 mm Hg after 30 minutes to 99+/-13 mm Hg after 60 minutes) while remaining unchanged after native hBNP (P=0.0387 between groups). CONCLUSIONS: This study reports for the first time that novel conjugated oral BNP activates cGMP and significantly reduces MAP, thus implying an efficacious coupling of CONJ-hBNP to the natriuretic receptor-A. These data advance a new concept of orally administered chronic BNP therapy for cardiovascular diseases.

Development and validation of an assay method for the determination of trifluoroacetic acid in a cyclosporin-like drug.

An improved method for the assay of trifluoroacetic acid (TFA) in a cyclosporin-like drug substance is presented, based on ion chromatography with suppressed conductivity detection. Column fouling by the drug molecule is avoided by use of a sample preparation method in which the drug substance is precipitated at alkaline pH whilst the TFA remains in solution. The new method requires a smaller sample mass than a previous method based on headspace-GC-FID whilst achieving an improvement in sensitivity. During validation, the method's performance was found to be consistent with usual acceptance criteria, and the method was found to be robust in routine use.