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Dose regimens2
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Adverse effects202
In the field study safety evaluation, 110 dogs received Zenalpha and 113 dogs received dexmedetomidine (control group) for sedation. Dogs ranged in age from 5 months to 14.5 years, weighed 5.1 to 154 lbs, and represented purebreds and breed mixes. Table 2. Adverse reactions during the field study Adverse Reaction Zenalpha(N = 110)n (%) Dexmedetomidine(N = 113)n (%) Diarrhea 4 (3.6) 0 (0) Muscle tremor 2 (1.8) 0 (0) Signs of colitis 2 (1.8) 0 (0) Hypothermia that necessitated use of an external heat source Hypothermia 1 (0.9) 13 (11.5) Vomiting 1 (0.9) 6 (5.3) Involuntary defecation 1 (0.9) 0 (0) Nausea 1 (0.9) 0 (0) Tachycardia, transient 1 (0.9) 0 (0) Prolonged sedation 0 (0) 3 (2.7) Urinary incontinence 0 (0) 2 (1.8) Retching 0 (0) 1 (0.9) Apnea 0 (0) 1 (0.9) Bradycardia 0 (0) 1 (0.9) Hyperthermia 0 (0) 1 (0.9)
Species not recordedOn-label (ON_LABEL)United States1 source record · View provenance
- Species not recorded · SPL section 34084-4 (ADVERSE REACTIONS SECTION) · United States · On-label (ON_LABEL) · Pending clinical review (PROPOSED) · Rule-based
2 As with all α-agonists, the potential for isolated cases of hypersensitivity, including paradoxical response (excitation), exists. Incidents of prolonged sedation, bradycardia, cyanosis, vomiting, apnea, death from circulatory failure with severe congestion of lungs, liver, kidney and recurrence of sedation after initial recovery have been reported.
Species not recordedOn-label (ON_LABEL)United States1 source record · View provenance
- Species not recorded · SPL section 34084-4 (ADVERSE REACTIONS SECTION) · United States · On-label (ON_LABEL) · Pending clinical review (PROPOSED) · Rule-based
These are counts of spontaneously reported events, not proven adverse effects, causal relationships, or incidence rates.
Bars compare report counts within each species; they do not show incidence.
More reportsFewer reportsDog
- Lack of efficacy - NOS278 reports
- Diarrhoea56 reports
- Sedation prolonged35 reports
- Bradycardia25 reports
- Vomiting24 reports
- Partial lack of efficacy22 reports
- Tachycardia21 reports
- Death19 reports
- Hypotension17 reports
- Vocalisation16 reports
- Involuntary defecation15 reports
- Twitching15 reports
Cat
- Tachycardia5 reports
- Death4 reports
- Blindness3 reports
- Cardiac arrest3 reports
- Fever3 reports
- Lethargy (see also Central nervous system depression in 'Neurological')3 reports
- Not eating3 reports
- Abnormal menace reflex test2 reports
- Adipsia2 reports
- Administration error NOS2 reports
- Anorexia2 reports
- Behavioural disorder NOS2 reports
Contraindications2
Do not use Zenalpha in dogs with cardiac disease, respiratory disorders, shock, severe debilitation, that have hypoglycemia or are at risk of developing hypoglycemia, or are stressed due to extreme heat, cold or fatigue. Zenalpha is contraindicated in dogs with a known sensitivity to medetomidine or vatinoxan.
Species not recordedOn-label (ON_LABEL)United States1 source record · View provenance
- Species not recorded · SPL section 34070-3 (CONTRAINDICATIONS SECTION) · United States · On-label (ON_LABEL) · Pending clinical review (PROPOSED) · Rule-based
Placadine should not be used in dogs with the following conditions: cardiac disease, respiratory disorders, liver or kidney diseases, dogs in shock, dogs which are severely debilitated, or dogs which are stressed due to extreme heat, cold or fatigue.
Species not recordedOn-label (ON_LABEL)United States1 source record · View provenance
- Species not recorded · SPL section 34070-3 (CONTRAINDICATIONS SECTION) · United States · On-label (ON_LABEL) · Pending clinical review (PROPOSED) · Rule-based
Precautions3
Federal law restricts this drug to use by or on the order of a licensed veterinarian.
Species not recordedOn-label (ON_LABEL)United States1 source record · View provenance
- Species not recorded · SPL section 34071-1 (WARNINGS SECTION) · United States · On-label (ON_LABEL) · Pending clinical review (PROPOSED) · Rule-based
Dogs should be monitored frequently during sedation for changes in heart rate, blood pressure, respiratory rate and body temperature. Tachycardia may occur in some dogs after recovery from sedation. In the event of hypoxia or apnea, supplemental oxygen should be administered. Following administration of Zenalpha, a decrease in body temperature may occur and an external heat source may be needed to maintain body temperature. Hypothermia may persist longer than sedation and analgesia. Effectiveness The analgesic effect of Zenalpha will not last longer than the sedative effects. Additional analgesic(s) should be administered as needed (see). Nervous, excited or agitated dogs with high levels of endogenous catecholamines may exhibit a reduced pharmacological response to Zenalpha (ineffectiveness). The onset of sedative/analgesic effects could be slowed, or the depth and duration of effects could be diminished or nonexistent. Therefore, allow the dog to rest quietly for 10 to 15 minutes after injection. 2 With the alpha-adrenoceptor agonist drug class, including Zenalpha, the potential for isolated cases of hypersensitivity, including paradoxical response (excitation) exists. Repeat dosing with Zenalpha has not been evaluated. Zenalpha has only been evaluated in fasted dogs; therefore, the effects on fed dogs (for example occurrence of vomiting) has not been characterized. The concurrent use of anticholinergic medications and Zenalpha has not been evaluated. Animal Safety Zenalpha may decrease serum glucose in healthy dogs and this effect may persist longer than sedation (see). The safe use of Zenalpha in dogs with hepatic or renal impairment has not been evaluated. The safe use of Zenalpha has not been evaluated in dogs younger than 4.5 months old. The safe use of Zenalpha has not been evaluated in dogs that are pregnant, lactating, or intended for breeding.
Species not recordedOn-label (ON_LABEL)United States1 source record · View provenance
- Species not recorded · SPL section 42232-9 (PRECAUTIONS SECTION) · United States · On-label (ON_LABEL) · Pending clinical review (PROPOSED) · Rule-based
2 In extremely nervous or excited dogs, levels of endogenous catecholamines are high due to the animal’s state of agitation. The pharmacological response elicited by α-agonists (e.g., medetomidine) in such animals is often reduced, with depth and duration of sedative/analgesic effects ranging from slightly diminished to nonexistent. Highly agitated dogs should therefore be put at ease and allowed to rest quietly prior to receiving Placadine. Allowing dogs to rest quietly for 10 to 15 minutes after injection may improve the response to Placadine. I n dogs not responding satisfactorily to treatment with Placadine, repeat dosing is not recommended. Caution should be exercised when handling sedated animals. Handling or any other sudden stimuli may cause a defense reaction in an animal that is sedated. 2 Placadine is a potent α-agonist which should be used with caution with other sedative or analgesic drugs. Additive or synergistic effects are likely, possibly resulting in overdose. Although bradycardia may be partially prevented by prior (at least 5 minutes before) intravenous administration of an anticholinergic agent, the administration of anticholinergic agents to treat bradycardia either simultaneously with medetomidine or following sedation with medetomidine could lead to adverse cardiovascular effects. Special care is recommended when treating very young animals and older animals. Information on the possible reproductive effects of medetomidine is limited; therefore, the drug is not recommended for use in dogs used for breeding purposes or in pregnant dogs.
Species not recordedOn-label (ON_LABEL)United States1 source record · View provenance
- Species not recorded · SPL section 42232-9 (PRECAUTIONS SECTION) · United States · On-label (ON_LABEL) · Pending clinical review (PROPOSED) · Rule-based
Pharmacokinetics2
2 2 2 Medetomidine is a potent non-narcotic alpha-adrenoceptor agonist which produces sedation and analgesia. These effects are dose dependent in depth and duration. Medetomidine is a racemic mixture containing the active enantiomer dexmedetomidine. Within the central nervous system, sympathetic neurotransmission is inhibited and the level of consciousness decreases. Respiratory rate and body temperature can also decrease. In the peripheral vasculature, medetomidine stimulates alpha-adrenoceptors within vascular smooth muscle which induces vasoconstriction and hypertension which consequently decreases the heart rate and cardiac output. Dexmedetomidine also induces a number of other alpha-adrenoceptor mediated effects, which include piloerection, depression of motor and secretory functions of the gastrointestinal tract, diuresis and hyperglycemia. 2 2 Vatinoxan is a peripherally selective alpha-adrenoceptor antagonist which lacks activity in the central nervous system. By limiting its effects to peripheral organ systems, vatinoxan will prevent or attenuate the cardiovascular and other effects of dexmedetomidine outside the central nervous system when administered simultaneously with the alpha-adrenoceptor agonist. The central effects of dexmedetomidine remain unaltered, although vatinoxan will reduce the duration of sedation and analgesia induced by dexmedetomidine, predominantly by increasing the clearance of the latter via improving the cardiovascular function. 2 2 2 2 No pharmacokinetic assessment was performed on Zenalpha [medetomidine (1 mg/m) + vatinoxan (20 mg/m)]. However, after IM administration of a pilot formulation of medetomidine (1 mg/m) + vatinoxan (30 mg/m), both medetomidine and vatinoxan were rapidly and highly absorbed from the injection site. Maximal plasma concentration was reached at 12.6 ± 4.7 (mean ± standard deviation) minutes and 17.5 ± 7.4 minutes for dexmedetomidine (the active enantiomer of medetomidine) and vatinoxan, respectively. Vatinoxan increased the volume of distribution and the clearance of dexmedetomidine. Thus, the clearance of dexmedetomidine was increased two-fold when given in combination with vatinoxan. The same phenomena were also observed with intravenous administration. Medetomidine plasma protein binding is high (85-90%). Medetomidine is mainly oxidized in the liver, a smaller amount undergoes methylation in the kidneys, and excretion is mainly via urine. Vatinoxan plasma protein binding is approximately 70%. Low levels are detectable in the central nervous system. Only a small amount (<5%) of vatinoxan dose has been found to be excreted via the urine.
Species not recordedOn-label (ON_LABEL)United States1 source record · View provenance
- Species not recorded · SPL section 34090-1 (CLINICAL PHARMACOLOGY SECTION) · United States · On-label (ON_LABEL) · Pending clinical review (PROPOSED) · Rule-based
2 Medetomidine is a potent non-narcotic α-adrenoreceptor agonist which produces sedation and analgesia. These effects are dose dependent in depth and duration. Profound sedation and recumbency, with reduced sensitivity to environmental stimuli (sounds, etc.), are seen with medetomidine. The pharmacological restraint and pain relief provided by medetomidine facilitates handling dogs and aids in the conduct of diagnostic or therapeutic procedures. It also facilitates minor surgical procedures (with or without local anesthesia) and dental care where intubation is not required. Spontaneous muscle contractions (twitching) can be expected in some dogs sedated with medetomidine. PRECAUTIONS With medetomidine administration, blood pressure is initially increased due to peripheral vasoconstriction and thereafter drops to normal or slightly below normal levels. The initial vasopressor response is accompanied by a compensatory marked decrease in heart rate mediated by a vagal baroreceptor mechanism. The bradycardia may be partially prevented by prior (at least 5 minutes before) intravenous administration of an anticholinergic agent (see). A transient change in the conductivity of the cardiac muscle may occur, as evidenced by atrioventricular blocks. Cardiovascular changes (such as profound bradycardia and second degree heart block) equally affect both heartworm negative and asymptomatic heartworm positive dogs. Respiratory responses include an initial slowing of respiration within a few seconds to 1–2 minutes after administration, increasing to normal within 120 minutes. An initial decrease in tidal volume is followed by an increase. When medetomidine was given at 3 and 5 times the recommended dose IV, and 5 and 10 times IM, effects were not intensified but were prolonged.
Species not recordedOn-label (ON_LABEL)United States1 source record · View provenance
- Species not recorded · SPL section 34090-1 (CLINICAL PHARMACOLOGY SECTION) · United States · On-label (ON_LABEL) · Pending clinical review (PROPOSED) · Rule-based
Literature references19
References are linked to this drug. Species applicability is not recorded here, so the species filter does not narrow this list. Imported dates do not retain their original precision; confirm dates in the original citation.
- Quality of domestic cat semen collected by urethral catheterization after the use of different alpha 2-adrenergic agonists.
Study summary not available in the imported record. Open the original citation to review the study.
- Cardiovascular effects of intravenous vatinoxan (MK-467) in medetomidine-tiletamine-zolazepam anaesthetised red deer (Cervus elaphus).
Study summary not available in the imported record. Open the original citation to review the study.
- Cardiovascular and sedation reversal effects of intramuscular administration of atipamezole in dogs treated with medetomidine hydrochloride with or without the peripheral α(2)-adrenoceptor antagonist vatinoxan hydrochloride.
Study summary not available in the imported record. Open the original citation to review the study.
- Effects of vatinoxan on cardiorespiratory function, fecal output and plasma drug concentrations in horses anesthetized with isoflurane and infusion of medetomidine.
Study summary not available in the imported record. Open the original citation to review the study.
- Effects of vatinoxan on cardiorespiratory function and gastrointestinal motility during constant-rate medetomidine infusion in standing horses.
Study summary not available in the imported record. Open the original citation to review the study.
Sources: DailyMed, U.S. National Library of Medicine; PubMed, National Library of Medicine; openFDA, U.S. Food and Drug Administration.
Available products
Products listed in the Health Canada Drug Product Database for this active ingredient. A listing does not establish that a product is authorized for the clinical uses described on this page.