Caudal Epidural Administration Research Articles

Comparative evaluation of sedative and anti-nociceptive effects of epidural romifidine, romifidine-lidocaine, and lidocaine in donkeys (Equus asinus).

Local and regional anesthetic procedures are valuable tools in veterinary practice. Caudal epidural administration of local anesthetic agents is widely reported for surgical interventions of the tail, anus, rectum, vulva, vagina, urethra, and bladder in the standing horse. Epidural analgesia is also obtained using various drugs such as alpha-2 adrenoceptor agonists, dissociative anesthetics, and opioids. The present study evaluates the anti-nociceptive and sedative effects of epidural administration of romifidine, a romifidine-lidocaine combination, and lidocaine alone in donkeys. In a randomized prospective study, twenty-four healthy adult donkeys were assigned to four groups (three experimental and one control; n = 6) received either 50 μg/kg of romifidine, 0.30 mg/kg of lidocaine, combined romifidine (50 μg/kg) and lidocaine (0.30 mg/kg) diluted in 0.9% sterile normal saline solution to a total injection volume of 12 ml, or an equivalent volume of sterile saline epidurally. After epidural injection of each treatment, the onset, degree, and duration of sedation and anatomical extension of anti-nociception were documented. Observations began immediately (time 0) pre-administration and at 5, 15, 30, 45, 60, and 30-min intervals subsequently until 210 min after drug injection. Time to onset of perineal analgesia was documented every minute after the epidural injection by evaluating the animal's response to pinpricks. Only romifidine and romifidine-lidocaine induced mild to moderate sedation. Romifidine, romifidine-lidocaine, and lidocaine induced complete bilateral caudal epidural analgesia with loss of sensation in the perineum, tail, inguinal region, caudal aspect of the upper hind limb, chest areas, and extended distally to the dorsal metatarsal area. Sedation lasted longer (p < 0.05) with romifidine (160 ± 15.4 min) than with romifidine-lidocaine (141.6 ± 13.2 min). Longer-lasting analgesia (p < 0.05) was obtained with romifidine (158.3 ± 9.8 min) and romifidine-lidocaine (165 ± 9.4 min) than with lidocaine (75.8 ± 8 min). Epidural administration of a single dose of romifidine or a combination of romifidine-lidocaine produced mild to moderate sedation and complete anti-nociception in the perineal and inguinal regions of donkeys. The clinical usefulness of epidural romifidine or romifidine-lidocaine combinations to perform obstetric procedures in donkeys needs to be assessed.

Comparative Evaluation of the Sedative and Analgesic Effects of Caudal Epidural Administration of Lidocaine Alone or in Combination With Xylazine, Detomidine, Medetomidine, and Dexmedetomidine in Mediterranean Miniature Donkeys

The present study aimed to compare the sedative and analgesic effects of caudal epidural administration of lidocaine alone or in combination with four different α2-adrenergic agonists in Mediterranean miniature donkeys. A total of ten clinically healthy (five males and five females) Mediterranean miniature donkeys with an age of 5 ± 1 years, a weight of 100 ± 2 kg and a height at the withers of 0.8 ± 0.06 m (mean ± standard deviation) were used in experimental, crossover (Latin square), randomized, and blinded study. Animals were assigned to five treatment groups including lidocaine alone (0.22 mg kg−1), or associated with one among xylazine (0.17 mg kg−1), detomidine (30 μg kg−1), medetomidine (15 μg kg−1), dexmedetomidine (5 μg kg−1) with a minimum washout period of 8 days between treatments. The degree of sedation was investigated using a simple descriptive scale of 0–3. Sedation scores were compared at each time using nonparametric (Kruskal–Wallis and Mann–Whitney U) tests. Analgesia was assessed by pinprick test. Sedation was greater in lidocaine and/or α2-adrenergic agonist groups than in lidocaine group at 45–75 minutes after drug administration (P < .05). There were no significant differences among groups in time to onset of analgesia and ataxia and also in number of animals with complete perineal analgesia and ataxia. Duration of analgesia and ataxia were longer in lidocaine and/or α2-adrenergic agonist groups than in lidocaine (P < .05). There were no significant differences among lidocaine and/or α2-adrenergic agonist groups in sedation score and duration of analgesia and ataxia. No significant differences were observed in heart and respiratory rate and also rectal temperature at any time points between groups and within groups. Caudal epidural administration of α2- adrenergic agonists associated with lidocaine resulted in sedative effects on Mediterranean miniature donkeys, while lidocaine alone did not induce sedation. These drugs associations should be considered when superior analgesia is advocated.

Role of Epidural Steroid Injection in Lumbar Spinal Stenosis—A Randomized Controlled Trial

Abstract Background Degenerative lumbar spinal stenosis (DLSS) is an important cause of pain and disability among the elderly and common indication for spinal surgery. However, due to age-related comorbidities, it becomes difficult for elderly patients of DLSS to immediately go for operative treatment. Caudal epidural steroid injection (CESI) can be an effective procedure for a selected group of patients who have chronic function-limiting lower back and lower extremity pain secondary to DLSS. The aim of this study was to compare the effects of CESI with physical therapy in patients afflicted with DLSS. Materials and Methods It is a single center, open-label randomized controlled trial conducted in department of Physical Medicine and Rehabilitation at a tertiary care center of northern India from January 2016 to August 2017 among DLSS patients. Trial was registered under the clinical trial registry of India. Patients were randomized in two groups–32 in intervention group A (CESI with local anesthetic and physical therapy) and 32 in control group B (physical therapy alone). Outcome measures were numerical pain rating scale (NPRS), Oswestry disability index (ODI), and mean claudication distance (MCD) at 3, 6, 12, and 24 weeks. Results NPRS and ODI showed significant improvement at 3, 6, 12, and 24 weeks (group A &gt;&gt; group B). Improvement in MCD was seen at each follow-up from baseline (group A &gt;&gt; group B). Conclusion Caudal epidural steroid administration can ameliorate pain, disability and claudication distance in DLSS patients, which provides them a window period for further definitive management.

Presumed generalised seizure following caudal epidural administration of morphine and detomidine in a pony

SummaryA 9‐year‐old show pony mare became acutely lame following removal of a bone sequestrum of the distal phalanx of the right thoracic limb. The mare also suffered from ongoing right dorsal colitis secondary to previous long‐term nonsteroidal anti‐inflammatory drug (NSAID) use. To avoid further NSAID use, a protocol for caudal epidural administration of morphine and detomidine in an increased volume was used to provide analgesia to the thoracic limbs. A total volume of 50 mL (0.2 mL/kg bwt) was administered over approximately 90 s. Immediately following the injection, the pony collapsed into lateral recumbency and experienced an apparent generalised seizure characterised by loss of consciousness and frantic paddling of all four limbs. The pony recovered rapidly without intervention, and no residual neurological deficits were noted. The epidural analgesia resulted in a marked improvement in comfort levels. The speed of injection is thought to have caused a change in epidural and intracranial pressures resulting in a generalised seizure and highlights the importance of administering large volumes slowly.

Comparative evaluation of hematobiochemical effects of caudal epidural administration of detomidine, lidocaine, and lidocaine/detomidine in dromedary calf camels

The present study aims to comparatively evaluate the effects of caudal epidural detomidine, lidocaine, and lidocaine/detomidine on hematobiochemical parameters in dromedary calf camels. A total of ten male dromedary calf camels (Camelus dromedarius) with the age of 20 ± 2 weeks and weight of 85 ± 5.5 kg were used for the study. The animals were enrolled to five groups (4 experimental and 1 control group) in a randomized, crossover Latin square design, with a minimum washout period of 7 days between treatments. Calves in groups DL and DH received epidural low (25 μg kg−1) and high (50 μg kg−1) dose of detomidine, respectively. Groups L and L/D received epidural lidocaine (0.22 mg kg−1) and lidocaine/detomidine (0.22 mg kg−1/50 μg kg−1), respectively. Calves in the control group were assigned to receive epidural normal saline. Correct spinal needle (18-gauge, 3.7 cm) insertion in the epidural space was confirmed by hanging drop method and loss of resistance to the drug injection. Blood samples were collected at T0 (baseline), T2, and T24 hours and were divided into two parts: one for hematological evaluation and the other one for serological analyses. Sera were analyzed for sodium (Na+), potassium (K+), calcium (Ca2+), creatinine (Cr), blood urea nitrogen (BUN), glucose (Glu), alanine transaminase (ALT), and aspartate transaminase (AST). One-way ANOVA with Tukey’s post hoc tests was used to compare mean values of hematobiochemical indices at similar times among different groups of studies. Except for packed cell volume (PCV), all hematological parameters showed no statistically significant changes during our experiment. At T24, PCV value decreased significantly in DH and L/D groups, compared with DL, L, and control groups (p ≤ 0.001). Serum concentrations of biochemical variables including Na+, Ca2+, ALT, AST, Cr, and BUN were not significantly different among all groups during the experiment (p > 0.05). At T24 hours, serum concentrations of K+ and Glu showed a significant increase in DH and L/D groups, compared with other studies groups (p < 0.05). Therefore, epidural high dose detomidine in combination with lidocaine is not recommended for calf camels suffering from conditions including hematological, metabolic, acid-base, and electrolyte problems.

Role of Caudal Epidural Block in enhanced recovery after pediatric oncologic surgery. Article

Introduction. Enhanced recovery after surgery and the early initiation of chemotherapy is a significant advantage of laparoscopic surgeries for malignant tumors of abdominal cavity in children. Despite the extensive experience in using caudal block in pediatric patients, it has not yet been determined whether the use of ultrasound navigation provides any clinical advantage in post-operative recovery after laparoscopic surgeries in pediatric oncology. Materials and methods. The study included 40 patients of Pediatric Oncology and Hematology, Federal Blokhin National Medical Research Center, ASA II–III, who underwent laparoscopic surgeries for malignant tumors of the abdominal cavity during 2017–2019. Patients were divided randomly into 2 groups. The CB (caudal blockade) group included 23 children. In CB group caudal epidural block as a regional component of combined anesthesia was used (CB group n = 23). GA (general anesthesia) group included 17 children who underwent general anesthesia (GA group, n = 17). Results. The median of the total dose of fentanyl in the CB group was 7.29 (6; 9.25) μg/kg, in the GA group — 10.7 (7.6; 12.5) μg/kg (р ≤ 0.012). In the postoperative period, patients in CB group didn’t require additional analgesia for 24 hours after caudal-epidural administration of morphine. After caudal-epidural administration of trimeperidin, 12 hours later. Enteral nutrition in children in the CB group was started in 4.7 ± 0.5 hours. In the GA group, enteral nutrition in 10 (59 %) patients was started in 20 hours after the end of the surgery. 5 children developed Conclusions. This study demonstrates that caudal epidural block for laparoscopic surgeries performed under ultrasound navigation provides effective analgesia in both perioperative and postoperative periods, promotes early start of enteral nutrition, minimizing the frequency of postoperative nausea and vomiting. Ultrasound navigation increases the likelihood of success and safety of the caudal epidural block.

Analgesic and sedative effects of caudal epidural tramadol in dromedary camels

This study aimed to investigate the analgesic efficacy of caudal epidural administration of tramadol in dromedary camels (Camelus dromedarius). A total of 10 dromedary camels of both sexes were selected and randomly assigned to one of two groups to receive epidurally either 1 mg/kg or 2 mg/kg of tramadol hydrochloride. The injections were made into the epidural space at first intercoccygeal junction. Using a pinprick method, analgesia was tested. Duration and onset of complete perineal analgesia were determined. Ataxia and sedation were also assessed and recorded. Clinical parameters including heart rate, respiratory rate and rectal temperature were measured. The lower dose (1 mg/kg) of tramadol induced analgesia only in the tail but the higher dose produced complete antinociception in the tail, anus and perineum. Analgesia of the hind limbs was not achieved after either doses of tramadol. The mean times to onset and duration of complete analgesia in camels receiving epidural tramadol at a dose of 2 mg/kg were 22±2.55 min and 65±8.66 min, respectively. Various degrees of ataxia occurred in all camels. Mild to deep sedation was observed following both doses. Mean heart rate, respiratory rate, and rectal temperature tended to increase for the first 15 or 30 min after injection. Based on the results of this study, analgesic effects of caudal epidural tramadol were dose dependent. Epidural tramadol at a dose of 2 mg/kg would provide suitable postoperative analgesia for various manipulations in the tail, anus and perineum in standing dromedary camels.

Evaluation of Low-Level Laser Effects on Epidural Anesthesia in Horse

Abstract Objective: To evaluate and compare the analgesic effects of caudal epidural administration of lidocaine (LIDO), caudal laser radiation and epidural lidocaine plus laser radiation in horses. Study design: A blinded, randomized, prospective, experimental cross-over study. Animals: Five healthy horses, 15.7 +/- 4.9 years of age, weighing 240 +/- 37 kg. Methods: The horses were randomly assigned to receive four treatments (group NS: saline (0.9% NaCl) solution via caudal epidural injection,group L: lidocaine( 2 mg/kg of body weight) via caudal epidural injection, group LLL: laser radiation (3000hrtz- for 10 minute) and group LL: caudal epidural lidocaine injection plus laser radiation at intervals of at least 1 week. Motor and sensory blockade evaluations used by TENS machine. perineal analgesia Anal and vaginal tone was recorded. Positive pain responses were defined as purposeful avoidance movements of the head, neck, trunk, limbs and tail. Absence of attempts to kick, bite and turning of the head toward the stimulation site were used to indicate analgesia. Results:.Analgesia produced in the tail, perineum and upper hind limb in all horses received lidocaine. Statistical analyses assessed sensory and motor stimulation and did not show a significant difference between horses in groups 1, 2, 3, 4 in right and left sides. Conclusion and clinical Relevance: We concluded that low level laser in combination with caudal epidural lidocaine treatments provided sufficient analgesia in horses, and this treatment is offered a longer duration of analgesia than laser, lidocaine caudal administration although the sensory and motor stimulation did not show significant difference between groups. Low level laser may be effective adjuvants in caudal epidural anesthesia in horses. Our results showed that LLL plus lidocaine may be preferable to a high dose of epidural lidocaine.

Effects of a Caudal Epidural Anesthesia Using Midazolam With or Without Lidocaine to Perform an Endometrial Biopsy in Mares

The aim of the study was to evaluate the effectiveness of midazolam in combination with lidocaine to induce caudal analgesia and cervical dilation to facilitate endometrial biopsy procedures. Eighteen mares undergoing endometrial biopsy were randomly allocated to three treatments groups that received epidural anesthesia (n = 6): 0.9% saline solution (SS) (6 mL, control group); midazolam maleate (MID) (0.05 mg/kg); and midazolam maleate (0.05 mg/kg) plus 2% lidocaine (MIDLID) (0.1 mg/kg). Systemic parameters, behavior, and motor blockade were measured at baseline and at 10, 30, and 60 minutes after treatments. A subjective score system was used to assess pain and cervical dilation during the reproductive procedures at the same time points. Satisfactory analgesia was recorded for both epidural midazolam treatment groups 8 ± 4 minutes postadministration of the drug; analgesia remained satisfactory until the end of the trial period (60 minutes, P > .05). All animals in the control group showed evident pain (P = .001) due to the analgesic tests and reproductive procedures. Cervical dilation (P = .0001) occurred 20 minutes after epidural injections for both treatment groups with midazolam, but this effect did not occur in the control treatment group. Systemic effects were not observed (P > .05) in baseline values or among treatment groups following caudal epidural administration of midazolam or midazolam/lidocaine treatments. Epidural analgesia using midazolam alone or the combination of midazolam and lidocaine may be a good alternative for painful reproductive and gynecologic procedures in mares.

Changes in Neuroglial Activity in Multiple Spinal Segments after Caudal Epidural Pulsed Radiofrequency in a Rat Model of Lumbar Disc Herniation

Background: Herniated lumbar discs can induce sciatica by mechanical compression and/ or chemical irritation. It was recently reported that neuroglial cellular activity after pulsed radiofrequency (PRF) application to a single dorsal root ganglion (DRG) attenuated neuroglial activity at the corresponding spinal dorsal horn. Recently, caudal epidural PRF has been used to manage neuropathic pain, but evidence of molecular changes after the administration of caudal epidural PRF to attenuate neuropathic pain is lacking, and it has not been determined whether caudal epidural PRF affects neuroglial activity at different spinal levels. Objectives: Using immunohistochemical methods in a rat model of lumbar disc herniation, the authors investigated the effects of caudal epidural PRF administration on pain-related behavior, on the activations of microglia and astrocytes in spinal cord, and on the expressions of calcitonin gene-related peptide (CGRP) and Transient receptor potential vanilloid 1(TRPV1) in the DRG at the L3, L4, L5, L6, and S1 levels. Study Design: Controlled animal trial. Setting: University hospital laboratory. Methods: Forty-five Sprague-Dawley rats were randomly assigned to a sham-operated group (n = 10) or a nucleus pulposus (NP)-exposed group (n = 35). Rats in the NP-exposed group were further subdivided into a NP-exposed with sham stimulation group (the NP-nonPRF group; n = 13) or a NP exposed with caudal epidural PRF stimulation group (the NP-PRF group; n = 22). Pulsed radiofrequency was administered on postoperative day 10 (POD 10) by placing an electrode in the caudal epidural space through the sacral hiatus and administering 5 Hz of PRF current for 600 seconds (maximum tip temperature 42°C). Rats were tested for mechanical allodynia on POD 10 and on days 7 and 14 after caudal epidural PRF administration (post-PRF). At 14 days post-PRF, sections of the spinal cord from L3, L4, L5, L6, and S1 were immunostained for ionized calciumbinding adapter molecule 1 (Iba1) and glial fibrillary acidic protein (GFAP), and DRGs from the same levels were immunostained for CGRP and TRPV1. Results: Mechanical withdrawal thresholds increased at 7 days post-PRF (P = 0.04), and the immunohistochemical expression of Iba1 in the L5 spinal dorsal horn and of CGRP in the L5 DRG were quantitatively reduced (P &lt; 0.001) at 14 days post-PRF. Furthermore, the upregulations of Iba1 at L3, L4, L6, and S1 dorsal horns and CGRP at L6 DRG were also attenuated by caudal epidural PRF (P &lt; 0.001). Limitation: We examined molecular changes only in ipsilateral lumbar regions and at 14 days post-PRF. Conclusion: Caudal epidural PRF reduced mechanical allodynia and downregulated microglia activity and CGRP expression at the lumbar disc herniated level and in adjacent lumbar spinal levels in a rat model of lumbar disc herniation. Key words: Caudal, pulsed radiofrequency, multisegmental, lumbar disc herniation, microglia, calcitonin gene-related peptide

Ultrasound versus fluoroscopy-guided caudal epidural steroid injection for the treatment of chronic low back pain with radiculopathy: A randomised, controlled clinical trial

Background and Aims:Caudal epidural steroid administration is an effective treatment for chronic low back pain (LBP). Fluoroscopy guidance is the gold standard for pain procedures. Ultrasound guidance is recently being used in pain clinic procedures. We compared the fluoroscopy guidance and ultrasound guidance for caudal epidural steroid injection with respect to the time needed for correct placement of the needle and clinical effectiveness in patients with chronic LBP.Methods:Fifty patients with chronic LBP with radiculopathy, not responding to conventional medical management, were randomly allocated to receive injection depot methyl prednisolone (40 mg) through caudal route either using ultrasound guidance (Group U, n = 25) or fluoroscopy guidance (Group F, n = 25). Pre-procedural visual analogue scale (VAS) score and Oswestry Disability Index (ODI) were noted. During the procedure, the time needed for correct placement of needle was observed. Adverse events, if any, were also noted. All patients were followed up for next 2 months to evaluate Visual Analogue Scale (VAS) score and ODI at the 2nd week and again at the end of 1st and 2nd month.Results:The needle-placement time was less using ultrasound guidance as compared to fluoroscopy guidance (119 ± 7.66 vs. 222.28 ± 29.65 s, respectively, P < 0.001). Significant reduction in VAS score and ODI (clinical improvement) was noted in the follow-up time points and comparable between the groups at all time points.Conclusion:Ultrasound guidance can be a safe alternative tool for achieving faster needle placement in caudal epidural space. Clinical effectiveness (reduction of VAS and ODI scores) remains comparable between both the techniques.

Caudal epidural anti-nociception using lidocaine, bupivacaine or their combination in cows undergoing reproductive procedures

ObjectiveTo evaluate the anti-nociceptive effects of lidocaine, lidocaine-bupivacaine combination or bupivacaine following caudal epidural administration in cows undergoing reproductive procedures. Study designBlinded, randomized experimental study. AnimalsThirty seven healthy Holstein cows (mean weight ± SD, 633 ± 41 kg). MethodsAnimals were allocated randomly to receive one of four treatments: group LID, 0.2 mg kg−1 lidocaine 2%; group LID-BUP, lidocaine-bupivacaine mixture in a 1:1 volume ratio (0.1 mg kg−1 and 0.025 mg kg−1, respectively); group BUP-LD, 0.05 mg kg−1 bupivacaine 0.5%; and group BUP-HD, 0.06 mg kg−1 bupivacaine 0.5%. The onset and duration of perineal anti-nociception were determined using superficial and deep pin pricks and the number of cows with complete perineal anti-nociception was recorded. Parameters were compared using anova followed by Duncan's test where relevant. ResultsMean ± SD time to onset of anti-nociception following epidural administration of BUP-LD was significantly longer than for LID-BUP (p < 0.05). The duration (in minutes) of perineal anti-nociception was significantly longer following epidural administration of BUP-HD (247 ± 31) versus LID-BUP (181 ± 33) and LID (127 ± 25) minutes respectively. The % of cows with complete anti-nociception was increased in the group treated with BUP-HD compared to BUP-LD. Severe ataxia or recumbency did not occur in any groups. Conclusions and clinical relevanceEpidurally administered bupivacaine, at a dose of 0.06 mg kg−1, may provide satisfactory caudal epidural anti-nociception for longer-duration obstetric and surgical procedures.

Analgesic effects of tramadol hydrochloride administered via caudal epidural injection in healthy adult cattle

To evaluate the extent and duration of analgesic effects of tramadol hydrochloride administered epidurally in standing healthy adult cattle. Animals-5 mixed-breed adult female cattle. 1, 2, or 3 mg of tramadol/kg was injected into the first intercoccygeal space of each cow in random order at 1-week intervals. Analgesia, sedation, and ataxia were scored on scales of 0 (no effect) to 3 (complete analgesia or extreme sedation or ataxia) at 5-minute intervals beginning 5 minutes prior to injection and ending 120 minutes after injection. Analgesia was evaluated on the basis of response to pinprick stimuli over 9 caudal regions. Heart rate, respiratory rate, rectal temperature, and rumen motility were assessed 5 minutes before and at predetermined intervals for 120 minutes after tramadol injection. Analgesia induced via tramadol administration was dose dependent (eg, mean duration of complete analgesia at the perineum was 18 minutes when cows received the 1 mg/kg dose, 60 minutes when cows received the 2 mg/kg dose, and 92 minutes when cows received the 3 mg/kg dose). Slight to mild sedation and ataxia were observed when cows received 2 or 3 mg of tramadol/kg. No significant tramadol-associated changes in heart rate, respiratory rate, rectal temperature, or rumen motility were detected. Caudal epidural tramadol administration induced analgesia with slight to mild sedation and ataxia in cows. Analgesia in affected regions after administration of 2 or 3 mg of tramadol/kg was considered sufficient to allow common surgical procedures to be performed in standing cattle.

Pharmacokinetics of Tramadol after Epidural Administration in Horses

Tramadol is a centrally acting analgesic structurally related to codeine and morphine. The aim of the present study was to evaluate the pharmacokinetic of tramadol and its major metabolites after caudal epidural administration in the horse. Six gelding male adult horses were assigned to receive epidural administration of tramadol at 2 mg/kg. Plasma substances detection was achieved using a HPLC-FL method. Tramadol was detectable after 5 minutes up to 8 hours after epidural administration. Metabolites plasma concentrations were found under the limit of quantification of the method; however negligible amounts of M2 was detected from 30 min up to 1 hour in three subjects. In conclusion, this study shows that tramadol administered by caudal route in horses produces plasma concentrations within the extrapolated therapeutic range from humans for sufficient time to provide analgesia. Further study of the drug's safety and efficacy for the treatment of pain in horses is warranted.

Pharmacokinetics of lidocaine in serum and milk of mature Holstein cows

The purpose of this study was to evaluate the pharmacokinetics of lidocaine in mature Holstein cows following an inverted L and caudal epidural nerve block. Plasma and milk concentrations were determined using high-performance liquid chromatography assay. Pharmacokinetic parameters were estimated using a noncompartmental method. Following administration via inverted L nerve block, serum T(max) was 0.521 +/- 0.226 h and serum C(max) was 572 +/- 207 ng/mL. Serum AUC was 1348 +/- 335 ng.h/mL. Apparent serum t((1/2)beta) was 4.19 +/- 1.69 h and MRT was 5.13 +/- 2.33 h with clearance uncorrected for the extent of absorption of 2.75 +/- 0.68 L/kg/h. The last measurable time of lidocaine detection in serum was 8.5 +/- 1.4 h with a mean concentration of 51 +/- 30 ng/mL. Milk T(max) was detected at 1.75 +/- 0.46 h with C(max) of 300 +/- 139 ng/mL. Milk AUC till the last time was 1869 +/- 450 ng.h/mL with the mean AUC milk to AUC serum ratio of 1.439 +/- 0.374. The last measurable time of lidocaine detection in milk was 32.5 +/- 16.2 h with a mean concentration of 46 +/- 30 ng/mL. There was no detectable lidocaine concentration in any samples following caudal epidural administration.

Meperidine prolongs lidocaine caudal epidural anaesthesia in the horse

The aim of the study was to evaluate and compare the effects of caudal epidural administration of meperidine (MP), lidocaine (LD), and a combination of the two (MPLD) in six mature saddle horses. Horses were randomly assigned to receive three treatments (MP 0.3 mg/kg; LD 0.2 mg/kg; and MPLD: MP 0.3 mg/kg and LD 0.2 mg/kg), with at least 1 week between treatments. Drugs were injected into the epidural space between the first and second coccygeal areas in conscious standing horses. Analgesia, ataxia, sedation, cardiovascular and respiratory effects, and rectal temperature were recorded at different intervals before (baseline) and after administration. Epidural administration of MPLD resulted in a longer duration of analgesia of the tail, perineum, and upper hind limb regions than did administration of MP or LD alone.

Plasma and cerebrospinal fluid alfentanil, butorphanol, and morphine concentrations following caudal epidural administration in horses

This study was conducted with the objective of determining the plasma and cerebrospinal fluid (CSF) concentrations after epidurally administered alfentanil, butorphanol, and morphine in horses. Five clinically healthy adult horses were studied. Morphine 0.1mg kg-1, alfentanil 0.02mg kg-1, and butorphanol 0.08mg kg-1 in equal volumes (20ml) were epidurally injected. A 10-ml sample of CSF and blood were drawn at sampling times before the epidural administration and at 5, 10, 20, 30, 40, 50, 60 and 120 minutes, and hourly for 24 hours Enzyme-linked immonosorbent assay (ELISA) was used as the screening test to detect the injected opioids. ANOVA and Bonferroni’s test were used with a P values &lt;0.05 considered significant. The ELISA method was used and seemed to be efficient to detect plasma and CSF epidurally administered alfentanil, butorphanol, and morphine in horses. Epidurally administered alfentanil produces fast cerebrospinal fluid levels that are higher than plasma levels. Less lipid soluble drugs such as morphine and butorphanol produce higher plasma levels than CSF levels for the same time point.

Pharmacokinetics of levobupivacaine after caudal epidural administration in infants less than 3 months of age

There are few data describing levobupivacaine pharmacokinetics in infants (<3 months) after caudal administration. An open-label study was undertaken to examine the pharmacokinetics of levobupivacaine 2.5 mg ml(-1), 2 mg kg(-1) in children aged less than 3 months after single-shot caudal epidural administration. Plasma concentrations were determined at intervals from 0.5 to 4 h after injection. A population pharmacokinetic analysis of levobupivacaine time-concentration profiles (84 observations) from 22 infants with mean postnatal age (PNA) 2.0 (range 0.6-2.9) months was undertaken using non-linear mixed effects models (NONMEM). Time-concentration profiles were analysed using a one-compartment model with first-order input and first-order elimination. Estimates were standardized to a 70 kg adult using allometric size models. Population parameter estimates (between-subject variability) for total levobupivacaine were clearance (CLt) 12.8 [coefficient of variation (CV) 50.6%] litre h(-1) 70 kg(-1), volume of distribution (Vt) 202 (CV 31.6%) litre 70 kg(-1), absorption half-life (Tabs) 0.323 (CV 18.6%) h 70 kg(-1). Estimates for the unbound drug were clearance (CLfree) 104 (CV 43.5%) litre h(-1) 70 kg(-1), volume of distribution (Vfree) 1700 (CV 44.9%) litre 70 kg(-1), absorption half-life (Tabsfree) 0.175 (CV 83.7%) h 70 kg(-1). There was no effect attributable to PNA on CL or V. Time to peak plasma concentration (Tmax) was 0.82 (CV 18%) h. Peak plasma concentration (Cmax) was 0.69 (CV 25%) microg ml(-1) for total levobupivacaine and 0.09 (CV 37%) microg ml(-1) for unbound levobupivacaine. Clearance in infants is approximately half that described in adults, suggesting immaturity of P450 CYP3A4 and CYP1A2 enzyme isoforms that metabolize levobupivacaine in infants. This lower clearance delays Tmax, which was noted to occur approximately 50 min after administration of caudal epidural levobupivacaine.

Pharmacokinetics of levobupivacaine 0.25% following caudal administration in children under 2 years of age

Levobupivacaine, the S(-)enantiomer of racemic bupivacaine is less cardiotoxic than racemic bupivacaine and the R(+)enantiomer dexbupivacaine, while retaining similar local anaesthetic properties and potency to racemic bupivacaine. The pharmacokinetic profiles of the two bupivacaine enantiomers differs and that of racemic bupivacaine may be age dependent. We examined the pharmacokinetics of levobupivacaine after its single shot caudal epidural administration in children. An open-label phase 2 study was undertaken to examine the pharmacokinetics of levobupivacaine 0.25% 2 mg kg(-1) in 49 children aged less than 2 yr, after single shot caudal epidural administration. Plasma concentrations were determined at intervals up to 60 min after caudal injection. Time to peak plasma concentration (T(max)) ranged between 5 and 60 min (median 30 min) and was reached later in children aged less than 3 months (P<0.005). Peak plasma concentration (C(max)) ranged between 0.41 and 2.12 micro g ml(-1) (median 0.80, mean (SD) 0.91 (0.40) micro g ml(-1)). After the caudal epidural administration of levobupivacaine 2 mg kg(-1) in children less than 2 yr of age, C(max) was within the accepted safe range for racemic bupivacaine. T(max) varied and occurred later in some children, particularly those aged less than 3 months. Sampling in future pharmacokinetic studies in this age group should extend beyond 60 min.

A comparison of the analgesic effects of caudal epidural methadone and lidocaine in the horse

ObjectiveTo evaluate and compare the effects of caudal epidural administration of methadone (METH) and lidocaine (LIDO) on tolerance to thermal stimulation over the dermatomes of the perineal, sacral, lumbar and thoracic regions in the horse. Study designA blinded, randomized, prospective, experimental cross–over study. AnimalsSeven healthy horses, 15.7 ± 4.9 years (mean ± SD) of age, weighing 536 ± 37 kg. MethodsThe horses were randomly assigned to receive two treatments (group M: METH, 0.1 mg kg−1 or group L: LIDO, 0.35 mg kg−1) at intervals of at least 28 days. An 18–gauge 80–mm Tuohy epidural needle was placed in the first intercoccygeal space (Co1–Co2) in awake standing horses restrained in stocks. Analgesia was assessed by use of a probe maintained at a constant 62 °C by circulating hot water. The maximum stimulation time was 30 seconds. Bilateral stimulation was performed at five defined points. Before drug administration, baseline values of response time to thermal stimuli were obtained. Time to response was then measured 15 and 60 minutes after METH or LIDO administration and then hourly until the response returned to baseline at all stimulation points on two further assessments. Development of any ataxia and/or sedation was recorded. Positive pain responses were defined as purposeful avoidance movements of the head, neck, trunk, limbs and tail. Absence of attempts to kick, bite and turning of the head toward the stimulation site were used to indicate analgesia. ResultsCaudal epidural administration of METH and LIDO significantly increased reaction time to thermal stimulation (one–sample t–test; p = 0.05). Analgesia in the perineal region was present 15 minutes after both METH and LIDO administration and progressed from caudal to cranial dermatones with time. The duration of a significant increase in reaction time was 5 hours after METH injection compared to 3 hours following LIDO. All horses defaecated and urinated normally, and no excitement, sedation or ataxia were observed after METH administration. The horses were unable to defaecate normally and were moderately to severely ataxic with hindlimb weakness after LIDO. ConclusionsCaudal epidural administration of methadone has considerable potential in the management of perineal, lumbo–sacral and thoracic pain in horses. Regional differences exist in the onset, duration and intensity of the pain relief. Clinical relevanceEpidural methadone administration provides analgesia with no measured side effects in these healthy adult horses.