Determination of the pharmacokinetics of a single oral dose of trazodone and its effect on the activity level of domestic pigeons (Columba livia)

Pharmacokinetics of Trazodone in Hispaniolan Parrots (Amazona ventralis)

The objective of this study was to establish the pharmacokinetics of a single oral dose of trazodone in the Hispaniolan Amazon parrot (Amazona ventralis). Trazodone is a selective serotonin antagonist and reuptake inhibitor used commonly in both human and veterinary medicine as an antidepressant behavioral modification medicine. A single oral dose of compounded trazodone hydrochloride solution (20 mg/mL) at 50 mg/kg was administered to a total of 7 healthy adult Hispaniolan Amazon parrots. The 7 healthy adult parrots ranged in age from 10 to 15 years and weighed 228 to 323g. Blood was collected at baseline (2 weeks before study) and at 1, 2, 4, 6, 10, and 14 hours post-drug administration. Plasma concentrations of both trazodone and its active metabolite m-chlorophenylpiperazine (mCPP) were measured via liquid chromatography tandem mass spectrometry. Noncompartmental pharmacokinetic analysis was completed. The half-life (t1/2) ± SD of trazodone for the Hispaniolan parrots was 1.89 ± 0.49 hours, and the t1/2 ± SD of mCPP metabolite was 1.9 ± 0.55 hours. Maximum serum drug concentrations, or Cmax (ng/mL), were 738.3 ± 285.3 for trazodone. Times to achieve Cmax (hours) for trazadone and the mCPP metabolite were 1 hour and 2 hours postdosing, respectively. While this study did not establish the behavioral effects of trazodone, no adverse side effects were observed throughout the 48-hour period following drug administration and blood collection. Our results indicate that the oral administration of a 50-mg/kg single dose of trazodone to Hispaniolan parrots may be considered a safe dose. Plasma concentrations are comparable to previously published values in humans, dogs, horses, and pigeons (Columba livia domestica) for up to 14 hours following dosing. This study indicates that further studies are needed to establish the pharmacodynamics and the efficacy of trazodone in the medical management of behavioral problems in psittacine species.

Pharmacokinetic, sedative, and physiological effects of oral compounded formulations of trazodone alone or in combination with gabapentin in male cats

Trazodone and gabapentin are common oral sedatives in cats, used alone or combined, but no pharmacokinetic studies exist for trazodone in this species. The objective of this study was to determine the pharmacokinetics of oral trazodone (T) alone, or in combination with gabapentin (G) in healthy cats. Cats (n = 6) were randomly allocated to receive T (3 mg/kg) intravenously (IV), T (5 mg/kg) orally (PO), or T (5 mg/kg) and G (10 mg/kg) PO with a 1-week washout period between treatments. Heart rate, respiratory rate, indirect blood pressure, and level of sedation were assessed, and venous blood samples were collected serially over 24 h. Analysis of plasma trazodone concentration was performed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Oral T administration resulted in a bioavailability of 54.9(7-96)%, and 17.2(11-25)% when administered with G. Tmax 0.17 (0.17-0.5) and 0.17 (0.17-0.75) h; Cmax 1.67 ± 0.91 and 1.22 ± 0.54 μg/mL, AUC 5.23 (2.0-18.76) and 2.37 (1.17-7.80) h*μg/mL; T1/2 5.12 ± 2.56 and 4.71 ± 1.07 h; for T and TG, respectively. Sedation was significant when compared to baseline in all groups from 20 or 45 min to 8 h indicating some lag between peak plasma concentration and sedative effects. Physiological variables remained within normal limits. This study concludes that oral trazodone is rapidly absorbed in healthy cats. Addition of gabapentin did not result in more profound sedation, showing no clinical advantage of combining these drugs in this study population.

EFFECTS OF A SINGLE ORAL DOSE OF TRAZODONE ON BEHAVIOR AND SERUM CORTISOL LEVELS IN BLUE WILDEBEEST (CONNOCHAETES TAURINUS)

Trazodone is a dose-dependent serotonin antagonist and agonist used to treat anxiety-related conditions. Trauma has been identified as the leading cause of morbidity and mortality in several nondomestic ruminant species and can be exacerbated by stress. In a recent study in domestic goats (Capra aegagrus hircus), trazodone reduced activity levels without adverse effects. Trazodone could allow for safer capture and handling in nondomestic ruminant species. The objectives of this study were to identify a dose of trazodone that decreases activity levels in captive blue wildebeest (Connochaetes taurinus) and to evaluate its safety and its effects on serum cortisol levels following a routine veterinary procedure. A pilot study using ethograms identified a group fed 15 mg/kg oral dose of trazodone as effective to reduce activity levels. Over 6 h, this dose resulted in a 111% increase in time spent sleeping or resting (P = 0.0003), a 41% increase in time spent lying down (P = 0.0016), a 64% reduction in time spent moving (P= 0.005), and a 65% reduction in time spent being vigilant (P= 0.026). Systemic absorption of trazodone was identified when plasma concentrations were measured after 2 h (95 ± 48 µg/L). Serum cortisol levels during a routine venipuncture event were not significantly different following trazodone administration (P > 0.05). Mild hyporexia was the only adverse effect noted at 15 mg/kg and was absent at a 12 mg/kg dose. Trazodone appears safe and promising to decrease activity in blue wildebeest and might thus have a positive effect on nondomestic ruminant welfare and the safety of veterinary procedures.

Backyard Poultry and Waterfowl Sedation and Anesthesia

The popularity of backyard poultry (chickens, turkey, guinea fowl) and waterfowl (ducks and geese) is increasing in the United States, and these animals frequently present for veterinary care. Like other birds, these species have unique anatomy that should be clinically considered before anesthesia. A balanced approach to an injectable, inhalational, or combination anesthesia protocol must be taken to ensure a safe outcome for the patient and to achieve the procedural needs. A well-informed clinician may use both sedation and general anesthesia to care for backyard bird patients in practice.

PHARMACOKINETICS AND CLINICAL EFFECTS OF A SINGLE ORAL DOSE OF TRAZODONE IN THE DOMESTIC GOAT (CAPRA HIRCUS) AS A MODEL FOR WILD RUMINANTS

Trazodone is an antianxiety medication commonly used in human and veterinary medicine. Stress-related trauma is the leading cause of morbidity and mortality in wild ruminant species. Trazodone could reduce stress and allow safer capture and handling, thus having a positive effect on their welfare. The objective of this study was to describe the clinical effects and pharmacokinetic profile of an oral dose of trazodone in domestic goats (Capra hircus) as a model for wild ruminants. A pilot study using ethograms and accelerometers identified an oral dose of 10 mg/kg as optimal to reduce activity levels. This dose resulted in a 502% increase in time spent sleeping (P=0.0016) and a 623% increase in time spent lying down (P=0.01). Additionally, there were reductions of 72% in time spent grooming (P=0.02), 49% in time spent moving (P=0.01), and 87% in time spent observing (P=0.0002). Activity levels were significantly decreased by 31% for 4 hr following administration (P=0.049). There were no observed adverse effects. Time spent eating or ruminating was not affected by trazodone administration (P > 0.05). The pharmacokinetics of trazodone following a single oral dose of 10 mg/kg in 7 goats was assessed. All animals achieved plasma concentrations over 130 ng/ml, a level considered therapeutic in humans and dogs, for a mean of 6.4 ± 5.0 hr. Mean terminal half-life was 10.55 ± 6.80 hr. All goats achieved maximum concentration within 5-15 min and still had detectable plasma levels at 24 hr. Trazodone appears promising to decrease stress in exotic ruminant species. Further research is warranted to establish its efficacy in other ruminant species and clinical situations.

Clinical Psychopharmacology for the Exotic Animal Practitioner

Literature regarding the clinical use of psychotropic drugs in exotic animals remains scarce. Psychotropic drugs acting on serotonin, dopamine, norepinephrine, and gamma-aminobutyric acid pathways work by decreasing fear and anxiety, reactivity, and hypervigilance, and by improving impulse control. They are indicated for some cases of aggression, self-mutilation, and compulsive and anxiety disorders, including feather-damaging behavior. Side effects are rarely seen when dosages are appropriately adjusted to the individual, starting with a low dose and slowly titrating to effect. Several drug interactions exist between psychotropic drugs and other classes. Psychotropic drugs cannot be used to replace appropriate environmental conditions in exotic animals. before "Side effects".