Cardiovascular effects of tramadol in dogs anesthetized with sevoflurane

Tramadol versus codeine and the short-term risk of cardiovascular events in patients with non-cancer pain: A population-based cohort study

AIMS

The effect of tramadol on the cardiovascular system is largely unknown. There is concern that, with its multimodal mechanism of action to increase serotonin and norepinephrine levels in the body, it could increase the risk of arterial ischaemia and cardiovascular events. We aimed to compare the short-term risk of cardiovascular events with the use of tramadol to that of codeine among patients with non-cancer pain.

METHODS

We conducted a retrospective population-based cohort study using data from the Clinical Practice Research Datalink (CPRD) with new users of tramadol or codeine from April 1998 to March 2017. Exposure was defined using an approach analogous to an intention-to-treat, with a maximum follow-up of 30 days. The primary endpoint was myocardial infarction, and secondary endpoints were unstable angina, ischaemic stroke, coronary revascularization, cardiovascular death and all-cause mortality. Hazard ratios (HRs) were estimated using Cox proportional hazards models, adjusted for high-dimensional propensity score.

RESULTS

The final cohort included 123 394 tramadol users and 914 333 codeine users. When tramadol was compared to codeine, the adjusted hazard ratio (HR) of myocardial infarction was 1.00 (95% CI 0.81-1.24). There was also no evidence of elevated risks of unstable angina (0.92; 95% CI 0.67-1.27), ischaemic stroke (0.98; 95% CI 0.82-1.17), coronary revascularization (0.97; 95% CI 0.69-1.38), cardiovascular death (1.07; 95% CI 0.93-1.23) or all-cause mortality (1.03; 95% CI 0.94-1.14) when tramadol was compared to codeine.

CONCLUSIONS

Short-term use of tramadol, compared with codeine, was not associated with an increased risk of cardiac events among patients with non-cancer pain.

In Vitro and In Vivo Pharmaco-Toxicological Characterization of 1-Cyclohexyl-x-methoxybenzene Derivatives in Mice: Comparison with Tramadol and PCP

1-cyclohexyl-x-methoxybenzene is a novel psychoactive substance (NPS), first discovered in Europe in 2012 as unknown racemic mixture of its three stereoisomers: ortho, meta and para. Each of these has structural similarities with the analgesic tramadol and the dissociative anesthetic phencyclidine. In light of these structural analogies, and based on the fact that both tramadol and phencyclidine are substances that cause toxic effects in humans, the aim of this study was to investigate the in vitro and in vivo pharmacodynamic profile of these molecules, and to compare them with those caused by tramadol and phencyclidine. In vitro studies demonstrated that tramadol, ortho, meta and para were inactive at mu, kappa and delta opioid receptors. Systemic administration of the three stereoisomers impairs sensorimotor responses, modulates spontaneous motor activity, induces modest analgesia, and alters thermoregulation and cardiorespiratory responses in the mouse in some cases, with a similar profile to that of tramadol and phencyclidine. Naloxone partially prevents only the visual sensorimotor impairments caused by three stereoisomers, without preventing other effects. The present data show that 1-cyclohexyl-x-methoxybenzene derivatives cause pharmaco-toxicological effects by activating both opioid and non-opioid mechanisms and suggest that their use could potentially lead to abuse and bodily harm.

Comparison of sedative and some cardiopulmonary effects of intramuscular medetomidine or medetomidine-tramadol in dogs

OBJECTIVE

To evaluate the clinical and physiologic effects of intramuscular (IM) administration of medetomidine with and without tramadol in dogs.

STUDY DESIGN

Prospective experimental study.

ANIMALS

A group of eight mixed breed dogs of both sexes, aged 1-2 years, weighing 16.0 ± 0.6 kg.

METHODS

Each dog was studied twice at ≥1 week interval. Medetomidine (5 μg kg^-1; treatment M) was administered IM alone or with tramadol (4 mg kg^-1; treatment MT). Sedation was scored by a system that included vocalization, posture, appearance, interactive behaviors, resistance to restraint and response to noise. Times from drug administration to ataxia, impaired walking, head drop, sternal and lateral position and standing were recorded. Sedation score, heart rate, respiratory rate, rectal temperature, end-tidal carbon dioxide (Pe'CO₂), hemoglobin oxygen saturation and mean noninvasive blood pressure were recorded and compared 15 minutes before and 15, 30 and 45 minutes after drug administration.

RESULTS

Dogs administered MT had higher sedation scores than dogs administered M at 30 and 45 minutes after drug administration (p < 0.05). Times to ataxia, impaired walking, head drop and sternal recumbency were not different between the treatments. Time to lateral recumbency was longer in M than in MT (21.1 ± 1.0 versus 17.6 ± 0.7 minutes, respectively; p < 0.05). Time to standing was longer in MT than in M (67.9 ± 1.4 versus 54.5 ± 1.9 minutes, respectively; p < 0.001). Measured physiological variables did not differ between the treatments, with the exception of Pe'CO₂, which was higher in MT than in M at all post-treatment evaluation times (p < 0.001).

CONCLUSIONS AND CLINICAL RELEVANCE

Tramadol combined with medetomidine resulted in greater sedation scores (deeper sedation) than medetomidine alone in dogs, and minimal adverse changes in the physiologic variables were measured.

Evaluating the effects of continuous intravenous infusions of tramadol and tramadol-lidocaine on sevoflurane minimum alveolar concentration (MAC) and entropy values in dogs

The sparing effects of tramadol and tramadol-lidocaine infusion on the minimum alveolar concentration (MAC) of sevoflurane in dogs as well as the entropy indices were investigated. Anesthesia was induced in eight young, healthy German shepherds weighing 27.6 ± 3.2 kg (mean ± SD) and maintained with sevoflurane. A standard tail-clamp technique was used to determine sevoflurane MAC during infusion with: sevoflurane alone to measure baseline MAC (MAC_B); tramadol (intravenous loading dose of 1.5 mg/kg and constant rate infusion [CRI] of 2.6 mg/kg/hr; MAC_T); and tramadol-lidocaine (tramadol CRI of 2.6 mg/kg/hr; and lidocaine intravenous loading dose of 1.0 mg/kg and CRI of 6 mg/kg/hr; MAC_TL). The state entropy (SE), response entropy (RE), and RE-SE difference were recorded 5 min prior to and during tail clamping. MAC_B was 2.4 ± 0.2%. Tramadol and tramadol-lidocaine CRI decreased MAC to 2.2 ± 0.3% and 1.7 ± 0.3%, respectively. The MAC-sparing effect of tramadol-lidocaine was greater than that of tramadol alone (8.2 ± 8.9% vs. 30.1 ± 10.7%; P<0.01). SE and RE in all subjects, and RE-SE difference in most subjects, were increased (all P<0.05) when they responded purposefully to noxious stimulation. A tramadol-lidocaine combination infusion can reduce anesthetic requirements to a higher degree than tramadol alone. Furthermore, MACentropy, MAC required to prevent increased entropy in response to a painful stimulation, and MAC of sevoflurane were similar in dogs.

2015 AAHA/AAFP pain management guidelines for dogs and cats

RATIONALE

The robust advances in pain management for companion animals underlie the decision of the American Animal Hospital Association (AAHA) and American Association of Feline Practitioners (AAFP) to expand on the information provided in the 2007 AAHA/AAFP Pain Management Guidelines. The 2015 Guidelines summarize and offer a discriminating review of much of this new knowledge.

RELEVANCE

Pain management is central to veterinary practice, alleviating pain, improving patient outcomes, and enhancing both quality of life and the veterinarian-client-patient relationship. These Guidelines support veterinarians in incorporating pain management into practice, improving patient care.

APPROACHES

The management of pain requires a continuum of care that includes anticipation, early intervention, and evaluation of response on an individual patient basis. A team-oriented approach, including the owner, is essential for maximizing the recognition, prevention and treatment of pain in animals.

EVIDENCE BASE

The Guidelines include both pharmacologic and non-pharmacologic modalities to manage pain; they are evidence-based insofar as possible and otherwise represent a consensus of expert opinion. Behavioral changes are currently the principal indicator of pain and its course of improvement or progression, and the basis for recently validated pain scores. Post-surgical pain is eminently predictable but a strong body of evidence exists supporting strategies to mitigate adaptive as well as maladaptive forms. Chronic pain is dominated by degenerative joint disease (DJD), which is one of the most significant and under-diagnosed diseases of cats and dogs. DJD is ubiquitous, found in pets of all ages, and inevitably progresses over time; evidence-based strategies for management are established in dogs, and emerging in cats.

Adjunctive, pain-modifying, analgesic drugs

Outside the realm of nonsteroidal antiinflammatory drug(NSAID) and opioid exist a broad range of medications that exert an analgesic effect, or otherwise modify and protect against pain, by manipulating various targets along the nociceptive pathway. Strength of evidence for dogs and cats can vary widely, and this article will review the available literature that may guide clinical usage in these species.

Evaluation of anesthetic, analgesic, and cardiorespiratory effects in dogs after intramuscular administration of dexmedetomidine-butorphanol-tiletamine-zolazepam or dexmedetomidine-tramadol-ketamine drug combinations

OBJECTIVE

To compare anesthetic, analgesic, and cardiorespiratory effects in dogs after IM administration of dexmedetomidine (7.5 μg/kg)-butorphanol (0.15 mg/kg)-tiletamine-zolazepam (3.0 mg/kg; DBTZ) or dexmedetomidine (15.0 μg/kg)-tramadol (3.0 mg/kg)-ketamine (3.0 mg/kg; DTrK) combinations.

ANIMALS

6 healthy adult mixed-breed dogs.

PROCEDURES

Each dog received DBTZ and DTrK in a randomized, crossover-design study with a 5-day interval between treatments. Cardiorespiratory variables and duration and quality of sedation-anesthesia (assessed via auditory stimulation and sedation-anesthesia scoring) and analgesia (assessed via algometry and electrical nerve stimulation) were evaluated at predetermined intervals.

RESULTS

DBTZ or DTrK induced general anesthesia sufficient for endotracheal intubation ≤ 7 minutes after injection. Anesthetic quality and time from drug administration to standing recovery (131.5 vs 109.5 minutes after injection of DBTZ and DTrK, respectively) were similar between treatments. Duration of analgesia was significantly longer with DBTZ treatment, compared with DTrK treatment. Analgesic effects were significantly greater with DBTZ treatment than with DTrK treatment at several time points. Transient hypertension (mean arterial blood pressure > 135 mm Hg), bradycardia (heart rate < 60 beats/min), and hypoxemia (oxygen saturation < 90% via pulse oximetry) were detected during both treatments. Tidal volume decreased significantly from baseline with both treatments and was significantly lower after DBTZ administration, compared with DTrK, at several time points.

CONCLUSIONS AND CLINICAL RELEVANCE

DBTZ or DTrK rapidly induced short-term anesthesia and analgesia in healthy dogs. Further research is needed to assess efficacy of these drug combinations for surgical anesthesia. Supplemental 100% oxygen should be provided when DBTZ or DTrK are used.

Reduction of the sevoflurane minimum alveolar concentration induced by methadone, tramadol, butorphanol and morphine in rats

This study aimed to estimate the reduction in the minimum alveolar concentration (MAC) of sevoflurane induced by low and high doses of methadone (5 and 10 mg/kg), tramadol (25 and 50 mg/kg), butorphanol (5 and 10 mg/kg) or morphine (5 and 10 mg/kg) in the rat. A control group received normal saline. Sixty-three adult male Sprague-Dawley rats were anaesthetized with sevoflurane ( n = 7 per group). Sevoflurane MAC was then determined before and after intraperitoneal administration of the opioids or saline. The duration of the sevoflurane MAC reduction and basic cardiovascular and respiratory measurements were also recorded. The baseline MAC was 2.5 (0.3) vol%. Methadone, tramadol and morphine reduced the sevoflurane MAC (low dose: 31 ± 10, 38 ± 15 and 30 ± 13% respectively; high dose: 100 ± 0, 83 ± 17 and 77 ± 25%, respectively) in a dose-dependent manner. The low and high doses of butorphanol reduced the sevoflurane MAC to a similar extent (33 ± 7 and 31 ± 4%, low and high doses, respectively). Two rats developed apnoea following administration of high-dose butorphanol and methadone. These anaesthetic-sparing effects are clinically relevant and may reduce the adverse effects associated with higher doses of inhalational anaesthetics.