Carolyn S. Brown

Analgesic effects of carprofen and liposome-encapsulated butorphanol tartrate in hispaniolan parrots (Amazona ventralis) with experimentally induced arthritis.

OBJECTIVE To evaluate the microcrystalline sodium urate (MSU) method for inducing arthritis in parrots and to compare the analgesic efficacy of long-acting liposome-encapsulated butorphanol (LEBT), carprofen, or a combination of both. ANIMALS 20 Hispaniolan parrots. PROCEDURES MSU was injected into a tibiotarsal-tarsometatarsal (intertarsal) joint to induce arthritis (time 0). Four treatments were compared (LEBT [15 mg/kg, SC] administered once at time 0; injections of carprofen [3 mg/kg, IM, q 12 h] starting at time 0; administration of LEBT plus carprofen; and a control treatment of saline [0.9% NaCl] solution). Weight load testing and behavioral scoring were conducted at 0, 2, 6, 26, and 30 hours. RESULTS Injection of MSU into the intertarsal joint induced arthritis, which resolved within 30 hours. Treatment with LEBT or LEBT plus carprofen resulted in significantly greater weight-bearing load on the limb with induced arthritis, compared with the control treatment. Treatment with carprofen alone caused a slight but nonsignificant improvement in weight-bearing load on the arthritic limb, compared with the control treatment. Behaviors associated with motor activity and weight bearing differed between the control and analgesic treatments. CONCLUSIONS AND CLINICAL RELEVANCE Butorphanol was an effective treatment for pain associated with arthritis, but carprofen administered every 12 hours was insufficient. Injection of MSU to induce arthritis in a single joint was a good method for evaluating tonic pain in parrots, and measurement of the weight-bearing load was accurate for assessment of arthritic pain; however, behavioral changes associated with pain were subtle.

Evaluation of liposome-encapsulated butorphanol tartrate for alleviation of experimentally induced arthritic pain in green-cheeked conures (Pyrrhura molinae).

OBJECTIVE To evaluate injection of microcrystalline sodium urate (MSU) for inducing articular pain in green-cheeked conures (Pyrrhura molinae) and the analgesic efficacy of liposome-encapsulated butorphanol tartrate (LEBT) by use of weight load data, behavioral scores, and fecal corticosterone concentration. ANIMALS 8 conures. PROCEDURES In a crossover study, conures were randomly assigned to receive LEBT (15 mg/kg) or liposomal vehicle subsequent to experimental induction of arthritis or sham injection. The MSU was injected into 1 tibiotarsal-tarsometatarsal (intertarsal) joint to induce arthritis (time 0). weight-bearing load and behavioral scores were determined at 0, 2, 6, 26, and 30 hours. RESULTS MSU injection into 1 intertarsal joint caused a temporary decrease in weight bearing on the affected limb. Treatment of arthritic conures with LEBT resulted in significantly more weight bearing on the arthritic limb than treatment with vehicle. Administration of vehicle to arthritic conures caused a decrease in activity and feeding behaviors during the induction phase of arthritis, but as the arthritis resolved, there was a significant increase in voluntary activity at 30 hours and feeding behaviors at 26 and 30 hours, compared with results for LEBT treatment of arthritic birds. Treatment with LEBT or vehicle in conures without arthritis resulted in similar measurements for weight bearing and voluntary and motivated behaviors. CONCLUSIONS AND CLINICAL RELEVANCE Experimental induction of arthritis in conures was a good method for evaluating tonic pain. Weight-bearing load was the most sensitive measure of pain associated with induced arthritis. Pain associated with MSU-induced arthritis was alleviated by administration of LEBT.

Liposome Dependent Delivery of N-(Phosphonacetyl)-L-Aspartic Acid to Cells in Vitro

AbstractN-(phosphonacetyl)-L-aspartic acid (PALA) exhibits a considerable increase in its in vitro growth inhibitory potency when it is incorporated into liposomes. Encapsulation in negatively charged liposomes increases the growth inhibitory potency of PALA by up to 360 times. For CV1-P and L929 cells, encapsulation in liposomes prepared from neutral phospholipids does not increase the potency of PALA. the potency of encapsulated PALA is not dependent on the size of liposomes, being equally effective in all liposomes between 0.1 and 1 µm in diameter. the potency of PALA is greatest when it is incorporated into liposomes prepared from high phase transition temperature lipids. Exposure of cells to 7.5 mM ammonium chloride substantially inhibits the effects of both free and encapsulated PALA. the potency of free PALA is more sensitive to changes in exposure length than is the potency of encapsulated PALA. Consequently the difference in potency between free and encapsulated PALA is greatest when exposure len...

Pharmacokinetics of a controlled‐release liposome‐encapsulated hydromorphone administered to healthy dogs

The purpose of the study was to assess the pharmacokinetics of liposome-encapsulated (DPPC-C) hydromorphone administered intravenously (IV) or subcutaneously (SC) to dogs. A total of eight healthy Beagles aged 12.13 +/- 1.2 months and weighing 11.72 +/- 1.10 kg were used. Dogs randomly received liposome encapsulated hydromorphone, 0.5 mg/kg IV (n = 6), 1.0 mg/kg (n = 6), 2.0 mg/kg (n = 6), or 3.0 mg/kg (n = 7) SC with a 14-28 day washout between trials. Blood was sampled at serial intervals after drug administration. Serum hydromorphone concentrations were measured using liquid chromatography with mass spectrometry. Serum concentrations of hydromorphone decreased rapidly after IV administration of the DPPC-C formulation (half-life = 0.52 h, volume of distribution = 12.47 L/kg, serum clearance = 128.97 mL/min/kg). The half-life of hydromorphone after SC administration of DPPC-C formulation at 1.0, 2.0, and 3.0 mg/kg was 5.22, 31.48, and 24.05 h, respectively. The maximum serum concentration normalized for dose (C(MAX)/D) ranged between 19.41-24.96 ng/mL occurring at 0.18-0.27 h. Serum hydromorphone concentrations fluctuated around 4.0 ng/mL from 6-72 h after 2.0 mg/kg and mean concentrations remained above 4 ng/mL for 96 h after 3.0 mg/kg DPPC-C hydromorphone. Liposome-encapsulated hydromorphone (DPPC-C) administered SC to healthy dogs provided a sustained duration of serum hydromorphone concentrations.

Liposome-mediated delivery of gallium to macrophage-like cells in vitro: demonstration of a transferrin-independent route for intracellular delivery of metal ions.

Gallium (Ga) prevents the activation of macrophages and might be useful as an immunosuppressive agent. It is taken up by the malignant cells through the transferrin (Tf) receptor pathway, but this pathway may be insufficient in the case of non-malignant cells. We studied the Tf-independent, liposome-mediated delivery of Ga to macrophage-like cells in vitro by a growth inhibition assay. The growth inhibitory properties of Ga for other types of cells was also evaluated. Ga complexed with nitrilotriacetate (GaNTA) and encapsulated in DSPG-liposomes was 16 and 48 times more potent for RAW 264 cells than free GaNTA and Ga-nitrate, respectively. CV1-P cells were also somewhat sensitive to liposomal Ga, but other cell lines with lower endocytotic capacity were insensitive. The inhibition of RAW 264 cell growth induced by liposomal or free GaNTA was partially reversed with iron-loading of the cells, indicating that this form of Ga causes an intracellular iron deficiency similar to that produced by Tf-bound Ga. Our results indicate that encapsulation of Ga in negatively charged liposomes provides a transferrin independent route for intracellular delivery of the compound to macrophages, which is of special interest in the treatment of autoimmune diseases, such as rheumatoid arthritis.

LDL Induced Association of Anionic Liposomes with Cells and Delivery of Contents as Shown by the Increase in Potency of Liposome Dependent Drugs

AbstractPurpose. To establish whether anionic liposomes interact with the low-density lipoprotein (LDL) receptor, to determine the role of lipoproteins in this interaction, and whether the association causes functional delivery of encapsulated drugs. Methods. The cell lines used were CV1-P and CHO wild type, both of which express the LDL receptor, and CHOldlA7, which lacks the LDL receptor. Cellular association of encapsulated methotrexate and fluorescein, labeled phosphatidylethanolamine in the lipid bilayer, was measured. Potency of three liposome dependent drugs (N-phosphonacetyl-L-aspartic acid, fluoroorotic acid, and methotrexate-γ-aspartate) was also measured by growth inhibition. Results. Association of liposomes containing at least 75 mol egg phosphatidylglycerol (ePG)/100 mol phospholipid with cells grown in defined medium supplemented with 1.0 mg/ml LDL was up to 30-fold higher with CV1-P or CHO wild type cells than with CHOldlA7, and 5-fold higher than association in defined medium lacking LDL. The addition of LDL did not yield any elevation of cellular association of distearoylphosphatidylglycerol liposomes. Increased association was paralleled by a corresponding increase in potency of all three liposome dependent drugs tested. Conclusions. ePG liposomes interact with the LDL receptor in an LDL-dependent fashion, and the interaction results in the delivery of contents to cells.

Experimental pharmacodynamics and analgesic efficacy of liposome-encapsulated hydromorphone in dogs.

The purpose of this study was to determine the experimental side effects of liposome-encapsulated hydromorphone (LE-Hydro) in beagles and to evaluate LE-Hydro analgesia in dogs undergoing ovariohysterectomies (OVH). Beagles were injected subcutaneously with 1-3 mg/kg LE-Hydro or 0.1 mg/kg hydromorphone. Dogs were evaluated for sedation, temperature, respiratory rate, and heart rate. OVH dogs were injected with 2 mg/kg LE-Hydro subcutaneously or 0.2 mg/kg morphine and 0.05 mg/kg acepromazine intramuscularly. Side effects of LE-Hydro were within clinically acceptable limits. The analgesic efficacy was superior in dogs administered LE-Hydro at 12 hr postsurgically. LE-Hydro provided adequate, durable analgesia in dogs undergoing OVH.

Pharmacokinetics and behavioral effects of an extended-release, liposome-encapsulated preparation of oxymorphone in rhesus macaques.

The objectives of the study were to determine the pharmacokinetics of oxymorphone (oxy) and of ammonium sulfate-loaded, liposome-encapsulated oxymorphone (LE-ASG oxy) and to evaluate the behavioral effects of both opioid preparations by using ethographic evaluation specific to rhesus monkeys. Rhesus monkeys (n = 8) were injected with 2.0 mg/kg LE-ASG oxy s.c.. Blood samples were collected at serial time points up to 144 h in six monkeys and up to 456 h in two monkeys. Separate groups of monkeys were injected with 0.1 mg/kg oxy s.c. (n = 4) or i.v. (n = 5). Blood samples were collected at serial time points up to 24 h after injection. Pharmacokinetic parameters were calculated by using commercially available software. Behavior was recorded in a different group of 10 monkeys administered LE-ASG oxy (2.0 mg/kg s.c.) or oxy (0.1 mg/kg s.c.) on separate occasions. Behavioral evaluations were made at serial time points while monkeys were in an extended cage with a compatible stimulus animal. Oxymorphone was rapidly eliminated from the serum in the oxy group. Measurable drug was present in serum for up to 4 h after oxy was administered subcutaneously or intravenously. LE-ASG oxy was present in serum in measurable concentrations for more than 2 weeks. Neither oxy nor LE-ASG oxy produced observable sedation. LE-ASG oxy decreased some environmentally directed behaviors, but this drug formulation increased watchfulness, decreased self-directed and elimination behaviors, increased nonspecific social contact, and decreased threat behaviors. LE-ASG oxy persisted for an extended period in rhesus monkey serum and produced behavioral changes consistent with this opioid.

Antinociceptive effects of long-acting nalbuphine decanoate after intramuscular administration to Hispaniolan Amazon parrots (Amazona ventralis)

OBJECTIVE To evaluate the thermal antinociceptive effects and duration of action of nalbuphine decanoate after IM administration to Hispaniolan Amazon parrots (Amazona ventralis). ANIMALS 10 healthy adult Hispaniolan Amazon parrots of unknown sex. PROCEDURES Nalbuphine decanoate (33.7 mg/kg) or saline (0.9% NaCl) solution was administered IM in a randomized complete crossover experimental design (periods 1 and 2). Foot withdrawal threshold to a noxious thermal stimulus was used to evaluate responses. Baseline thermal withdrawal threshold was recorded 1 hour before drug or saline solution administration, and thermal foot withdrawal threshold measurements were repeated 1, 2, 3, 6, 12, 24, 48, and 72 hours after drug administration. RESULTS Nalbuphine decanoate administered IM at a dose of 33.7 mg/kg significantly increased thermal foot withdrawal threshold, compared with results after administration of saline solution during period 2, and also caused a significant change in withdrawal threshold for up to 12 hours, compared with baseline values. CONCLUSIONS AND CLINICAL RELEVANCE Nalbuphine decanoate increased the foot withdrawal threshold to a noxious thermal stimulus in Hispaniolan Amazon parrots for up to 12 hours and provided a longer duration of action than has been reported for other nalbuphine formulations. Further studies with other types of nociceptive stimulation, dosages, and dosing intervals as well as clinical trials are needed to fully evaluate the analgesic effects of nalbuphine decanoate in psittacine birds.

Pharmacokinetics of long-acting nalbuphine decanoate after intramuscular administration to Hispaniolan Amazon parrots (Amazona ventralis)

OBJECTIVE To evaluate the pharmacokinetics of nalbuphine decanoate after IM administration to Hispaniolan Amazon parrots (Amazona ventralis). ANIMALS 9 healthy adult Hispaniolan Amazon parrots of unknown sex. PROCEDURES Nalbuphine decanoate (37.5 mg/kg) was administered IM to all birds. Plasma samples were obtained from blood collected before (time 0) and 0.25, 1, 2, 3, 6, 12, 24, 48, and 96 hours after drug administration. Plasma samples were used for measurement of nalbuphine concentrations via liquid chromatography-tandem mass spectrometry. Pharmacokinetic parameters were estimated with computer software. RESULTS Plasma concentrations of nalbuphine increased rapidly after IM administration, with a mean concentration of 46.1 ng/mL at 0.25 hours after administration. Plasma concentrations of nalbuphine remained > 20 ng/mL for at least 24 hours in all birds. The maximum plasma concentration was 109.4 ng/mL at 2.15 hours. The mean terminal half-life was 20.4 hours. CONCLUSIONS AND CLINICAL RELEVANCE In Hispaniolan Amazon parrots, plasma concentrations of nalbuphine were prolonged after IM administration of nalbuphine decanoate, compared with previously reported results after administration of nalbuphine hydrochloride. Plasma concentrations that could be associated with antinociception were maintained for 24 hours after IM administration of 37.5 mg of nalbuphine decanoate/kg. Safety and analgesic efficacy of nalbuphine treatments in this species require further investigation to determine the potential for clinical use in pain management in psittacine species.