Serum Buprenorphine Concentrations and Behavioral Activity in Mice After a Single Subcutaneous Injection of Simbadol, Buprenorphine SR-LAB, or Standard Buprenorphine.

Buprenorphine, an analgesic commonly used in rodent surgery, requires repeated dosing every 4 to 6 h in order to provide adequate analgesia. However, redosing requires repeated handling, which may itself cause stress. Buprenorphine SR-LAB, which reportedly maintains serum levels of buprenorphine greater than 1 ng/mL for 48 to 72 h, is commercially available. However, the viscosity of the product and small dosing volumes make accurate dosing a challenge. Simbadol is a concentrated formulation of buprenorphine hydrochloride labeled for use in cats with recommended dosing frequency of every 24 h. We measured serum concentrations over time after a single injection of this product in C57BL/6NCrl mice and compared it to standard buprenorphine (Buprenex) and Buprenorphine SR-LAB. Male and female mice were injected subcutaneously with one of the 3 buprenorphine formulations at a dose of 1 mg/kg at time 0. Groups of mice (n = 8) were euthanized at 1, 4, 8, 12, 16 h for all groups and 24 h for the Simbadol and the Buprenorphine SR-LAB. Liquid chromatography-mass spectrometry (LC-MS/MS) was used to determine concentrations of buprenorphine in each serum sample. High concentrations were observed in both Simbadol and standard buprenorphine groups one hour after injection (>50 ng/mL). These groups had similar buprenorphine concentration curves, including rates of decline. The standard buprenorphine group had mean concentrations less than 1 ng/mL by 12 h and the Simbadol group by 16 h. In contrast, the Buprenorphine SR-LAB group remained above the 1 ng/mL therapeutic threshold throughout the 24 h. In addition, clinical signs, including increased activity, that lasted for up to an hour after the injection in the Simbadol and standard buprenorphine groups. We conclude that Simbadol does not offer dosing advantages over the standard buprenorphine formulation when given at 1 mg/kg. Buprenorphine SR-LAB maintained a steady concentration of buprenorphine above 1 ng/mL for at least 24 h, and as such is a superior choice for providing long-term analgesia.

Effects of Buprenorphine, Chlorhexidine, and Low-level Laser Therapy on Wound Healing in Mice.

Systemic buprenorphine and topical antiseptics such as chlorhexidine are frequently used in research animals to aid in pain control and to reduce infection, respectively. These therapeutics are controversial, especially when used in wound healing studies, due to conflicting data suggesting that they delay wound healing. Low-level laser therapy (LLLT) has been used to aid in wound healing without exerting the systemic effects of therapies such as buprenorphine. We conducted 2 studies to investigate the effects of these common treatment modalities on the rate of wound healing in mice. The first study used models of punch biopsy and dermal abrasion to assess whether buprenorphine HCl or 0.12% chlorhexidine delayed wound healing. The second study investigated the effects of sustained-released buprenorphine, 0.05% chlorhexidine, and LLLT on excisional wound healing. The rate of wound healing was assessed by obtaining photographs on days 0, 2, 4, 7, and 9 for the punch biopsy model in study 1, days 0, 1, 2, 4, 6, 8, 11, and 13 for the dermal abrasion model in study 1, and days 0, 3, 6, and 10 for the mice in study 2. Image J software was used to analyze the photographed wounds to determine the wound area. When comparing the wound area on the above days to the original wound area, no significant differences in healing were observed for any of the treatment groups at any time period for either study. Given the results of these studies, we believe that systemic buprenorphine, topical chlorhexidine, and LLLT can be used without impairing or delaying wound healing in mice.

Inhaled high molecular weight hyaluronan ameliorates respiratory failure in acute COPD exacerbation: a pilot study.

BACKGROUND: Acute exacerbations of chronic obstructive pulmonary disease (AECOPD) carry significant morbidity and mortality. AECOPD treatment remains limited. High molecular weight hyaluronan (HMW-HA) is a glycosaminoglycan sugar, which is a physiological constituent of the lung extracellular matrix and has notable anti-inflammatory and hydrating properties. RESEARCH QUESTION: We hypothesized that inhaled HMW-HA will improve outcomes in AECOPD. METHODS: We conducted a single center, randomized, placebo-controlled, double-blind study to investigate the effect of inhaled HMW-HA in patients with severe AECOPD necessitating non-invasive positive-pressure ventilation (NIPPV). Primary endpoint was time until liberation from NIPPV. RESULTS: Out of 44 screened patients, 41 were included in the study (21 for placebo and 20 for HMW-HA). Patients treated with HMW-HA had significantly shorter duration of NIPPV. HMW-HA treated patients also had lower measured peak airway pressures on the ventilator and lower systemic inflammation markers after liberation from NIPPV. In vitro testing showed that HMW-HA significantly improved mucociliary transport in air-liquid interface cultures of primary bronchial cells from COPD patients and healthy primary cells exposed to cigarette smoke extract. INTERPRETATION: Inhaled HMW-HA shortens the duration of respiratory failure and need for non-invasive ventilation in patients with AECOPD. Beneficial effects of HMW-HA on mucociliary clearance and inflammation may account for some of the effects (NCT02674880, www.clinicaltrials.gov ).

Evaluation of buprenorphine hydrochloride Pluronic(®) gel formulation in male C57BL/6NCrl mice.

Providing adequate analgesia while minimizing handling and stress post-surgery can be challenging. Recently, there have been commercial products made available for providing long acting analgesia in rodents. However, we find there are limitations for use in mice due to the viscosity of the product and the small dosing volumes needed. This project evaluated an in-house compounded formulation of buprenorphine easily made in the laboratory using pharmaceutical grade products. The release of buprenorphine was evaluated when compounded with two types of hydrogels (Pluronic(®) F-127 and F-68). Mice given buprenorphine in hydrogel (BP) demonstrated higher serum levels of buprenorphine for a longer period of time compared to mice given standard buprenorphine (Bup). However, the rate of decline in serum levels between the groups was similar; thus, it is more likely that the higher buprenorphine concentration seen in the BP group is due to the higher dose of buprenorphine given, rather than a slower release of product. Feed consumption was decreased in both groups one day after dosing; however, there was no difference in body weights. Increased activity in the open field was observed with both buprenorphine formulations, and lipemia was observed in mice given BP which persisted to at least 96 h. Based on our results, we conclude that this formulation did not sustain the release of buprenorphine or eliminate the increased activity commonly seen in mice given buprenorphine. In addition, the lipemia may confound research parameters, especially in cardiac studies and lipid metabolism studies. Therefore, we cannot recommend this formulation for use.