Diclofenac readily penetrates the cerebrospinal fluid in children

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

Diclofenac, a nonselective nonsteroidal anti-inflammatory drug,, exerts analgesic action both in the peripheral tissues and in the central nervous system by inhibiting cyclooxygenase enzymes COX-1/2, but central nervous system penetration of diclofenac has not been evaluated in humans.

WHAT THIS STUDY ADDS

Diclofenac penetrates the cerebrospinal fluid rapidly, and after a single intravenous dose of 1 mg kg(-1), sufficient concentrations to inhibit COX-1/2 are sustained for up to 4 h.

AIMS

The primary aim was to study the cerebrospinal fluid (CSF) penetration of intravenous diclofenac in children. The secondary aim was to evaluate the plasma diclofenac concentration at the onset of wound pain after inguinal surgery in children.

METHODS

A total of 31 children (24 boys) aged 3 months to 12 years received a single intravenous injection of diclofenac 1 mg kg(-1). Paired CSF and blood samples were obtained 5 min to 22 h (median 69 min) later. In children having inguinal surgery a second blood sample was obtained at the time that the children felt wound pain for the first time after surgery. Diclofenac concentrations in CSF, plasma and protein free plasma were measured by gas chromatography with mass spectrometric detection.

RESULTS

In the 28 CSF samples obtained at 5 min to 3 h 43 min after injection, diclofenac concentrations ranged between 0.5 and 4.7 microg l(-1). At 5.5 h the CSF concentration was 0.1 microg l(-1), and no diclofenac was detected in the two CSF samples obtained at 22 h. The median of plasma diclofenac concentration at the time when pain returned after inguinal surgery was 104 microg l(-1) (range 70-272 microg l(-1)). No serious or unexpected adverse effects were reported.

CONCLUSIONS

Diclofenac penetrates the CSF rapidly, and a sufficient concentration to inhibit cyclooxygenase enzymes is sustained for up to 4 h.

How readily does ketorolac penetrate cerebrospinal fluid in children?

Ketorolac is a potent nonsteroidal anti-inflammatory analgesic used in postoperative pain management. Ketorolac elicits its analgesic action by inhibiting the cyclo-oxygenase enzyme in peripheral tissues and in the spinal cord. Central nervous system penetration of parenteral ketorolac has been evaluated in adults but not in children. In the present study we investigated ketorolac cerebrospinal fluid penetration via spinal anesthesia in 30 healthy children undergoing surgery in the lower part of the body. A single cerebrospinal fluid and blood sample was obtained between 11 minutes and 6 hours after receiving ketorolac 0.5 mg x kg(-1) IV. Ketorolac concentrations were determined by gas chromatography with mass spectrometric detection. Ketorolac was detected from 22 of the 30 cerebrospinal fluid samples, and the concentrations ranged between 0.2 and 7.6 microg x L(-1) (median, 0.6 microg x L(-1)). The cerebrospinal fluid to unbound plasma concentration-ratio ranged between 0.01 and 0.69 (median, 0.08). These low concentrations indicate that ketorolac does not readily penetrate cerebrospinal fluid in children.

Cerebrospinal fluid distribution of ibuprofen after intravenous administration in children

BACKGROUND

Ibuprofen is the most commonly used nonsteroidal, antipyretic, antiinflammatory analgesic in children. Nonsteroidal, antipyretic, antiinflammatory analgesics act in both the peripheral tissues and the central nervous system. The central nervous system penetration of ibuprofen has been described in adults but not in children.

OBJECTIVES

Our goals were to investigate the cerebrospinal fluid penetration of ibuprofen in children and evaluate the analgesic plasma concentration of ibuprofen after inguinal surgery in children.

MATERIALS AND METHODS

A total 36 healthy children (25 boys) aged 3 months to 12 years received a single intravenous injection of ibuprofen (10 mg/kg). A paired cerebrospinal fluid and blood sample was obtained 10 minutes to 8 hours after the injection. In children having inguinal surgery, a second blood sample was obtained at the time that the child first had wound pain.

RESULTS

The ibuprofen level was determined in all cerebrospinal fluid and plasma samples. Cerebrospinal fluid concentrations ranged between 15 and 541 microg/L, and the highest concentrations were measured 30 to 38 minutes after dosing. In all cerebrospinal fluid samples collected after 30 minutes, ibuprofen concentration exceeded that of unbound plasma. The plasma analgesic concentrations after inguinal surgery ranged between 10 and 25 mg/L.

CONCLUSIONS

Ibuprofen penetrates the cerebrospinal fluid readily, with peak concentrations attained 30 to 40 minutes after intravenous injection of a 10 mg/kg dose. The plasma analgesic concentration after inguinal surgery with spinal anesthesia is 10 to 25 mg/L.

Regular tramadol use does not affect the propofol dose requirement for induction of anaesthesia

BACKGROUND AND OBJECTIVES

An increased risk of awareness during general anaesthesia in patients receiving tramadol has been reported. We studied whether tramadol affects the amount of propofol required for induction of anaesthesia.

METHODS

In this prospective controlled study, we evaluated 46 patients, half of whom used tramadol regularly. Entropy indices, state entropy and response entropy, were used to assess the level of hypnosis. Patients were anaesthetized with a propofol infusion (1 mg kg(-1) min(-1)) until they first became unconscious, and further until they developed a burst suppression pattern in the electroencephalogram. The doses of propofol needed to reach these end-points were recorded.

RESULTS

The amount (median, (range)) of propofol required for loss of consciousness was 2.0 (1.0-5.5) mg kg(-1) and 2.4 (0.9-8.3) mg kg(-1) (P=0.95) in the tramadol users and controls, respectively. The amount of propofol required for burst suppression was 5.8 (3.9-12.7) mg kg(-1) and 6.4 (2.9-15.1) mg kg(-1) (P=0.89) in the tramadol users and controls. There was no difference between the groups in state entropy and response entropy during different stages of induction of anaesthesia.

CONCLUSIONS

Tramadol did not affect the dose of propofol required to achieve loss of consciousness or burst suppression pattern in electroencephalogram during induction of general anaesthesia. However, there was a ninefold inter-individual variation in propofol dose requirement for loss of consciousness and a fivefold variation for reaching burst suppression. Due to extensive inter-individual variability, monitoring the level of hypnosis during general anaesthesia using propofol may enhance the correct dosage.

Paracetamol (acetaminophen) penetrates readily into the cerebrospinal fluid of children after intravenous administration

INTRODUCTION

The main action of paracetamol (acetaminophen) is presumed to be in the central nervous system. The central nervous system penetration of paracetamol has been described in children with intracranial pathologies but not in children with an intact blood-brain barrier.

OBJECTIVE

We investigated the cerebrospinal fluid penetration of paracetamol in 32 healthy children, aged 3 months to 12 years, who were undergoing surgery in the lower body using spinal anesthesia.

MATERIALS AND METHODS

In this open-label prospective study, children were given a single intravenous injection of paracetamol (15 mg/kg). Cerebrospinal fluid and venous blood samples were obtained between 5 minutes and 5 hours after injection. Paracetamol concentrations were determined from the cerebrospinal fluid and plasma by using a fluorescence polarization immunoassay.

RESULTS

Paracetamol was detected in cerebrospinal fluid from the earliest sample at 5 minutes, although in this sample paracetamol concentration was below the limit of quantification of 1.0 mg/L. Subsequent paracetamol concentrations in cerebrospinal fluid ranged between 1.3 and 18 mg/L (median: 7.2 mg/L), plasma concentrations ranged between 2.4 and 33 mg/L, and cerebrospinal fluid/plasma ratios ranged between 0.06 and 2.0. The highest CSF paracetamol concentration was detected at 57 minutes.

CONCLUSIONS

Paracetamol permeates readily into the cerebrospinal fluid of children. This fast and extensive transfer enables the rapid central analgesic and antipyretic action of intravenous paracetamol.

Plasma and cerebrospinal fluid concentrations of indomethacin in children after intravenous administration

The objective of this study was to evaluate the cerebrospinal fluid (CSF) permeation of indomethacin in healthy children. The participants (n = 31, aged 4-144 months) received indomethacin (0.35 mg/kg) as a 10-minute intravenous infusion prior to surgery under spinal anaesthesia. A single CSF and plasma sample from each individual was collected 14 to 225 minutes after the infusion. Indomethacin concentrations were determined from the CSF, plasma, and protein-free plasma. Total plasma, protein-free plasma, and CSF concentrations of indomethacin ranged between 90 and 2200 ng/mL (median, 780 ng/mL), 0.3 and 0.8 ng/mL (median, 0.5 ng/mL), and 0.2 and 5.0 ng/mL (median, 1.4 ng/mL), respectively. The CSF to plasma concentration ratio remained less than 0.01. There was no correlation between the administration time and CSF concentrations. Eleven children developed 12 nonserious adverse effects, from which 5 were central nervous system (CNS) effects (agitation). In conclusion, indomethacin permeated into the CSF of children, which enables both desired and adverse CNS effects of indomethacin.

Effects of cigarette smoking on serum fluoride concentrations and renal function integrity after 1 MAC-h sevoflurane anaesthesia

BACKGROUND

Tobacco smoke contains various chemicals which may affect drug metabolism. Sevoflurane is metabolized to inorganic fluoride, and elevated serum fluoride concentrations (S-F(-)) may cause deterioration of renal function. Whether smokers develop high S-F(-) and associated disturbances in renal function is not known.

METHODS

We investigated sevoflurane metabolism in 25 non-smoking and 25 smoking (> 10 cigarettes/day) generally healthy women, aged 19-68 years, undergoing gynaecological elective surgery under one minimum alveolar concentration-hour (1 MAC-h) standardized sevoflurane anaesthesia. S-F(-) was measured for 24 h. Glomerular and tubular function was assessed by measuring serum and urine tumour-associated trypsin inhibitor (TATI), beta(2)-microglobulin and serum creatinine for 48 h after sevoflurane inhalation.

RESULTS

There were no differences between the two study groups with regard to S-F(-). It increased significantly in both groups: in non-smokers, from a baseline between 1.0 and 11 micromol/l (median, 1.6 micromol/l) to a maximum between 8.2 and 40 micromol/l (26 micromol/l) (P < 0.001) and, in smokers, from a baseline between 0.5 and 5.2 micromol/l (1.7 micromol/l) to a maximum between 19 and 71 micromol/l (25 micromol/l) (P < 0.001). In both groups, S-F(-) remained elevated for the entire sampling period (P < 0.001). In all five women (one non-smoker and four smokers) with a maximum S-F(-) of 40 micromol/l or higher and an area under the serum fluoride concentration-time curve (AUC(F0-24)) of 500 micromol/h/l or higher, serum TATI increased above the pathological concentration of 3.0 nmol/l, whereas only six of the 45 patients with S-F(-) below 40 micromol/l had serum TATI above 3.0 nmol/l (P < 0.001). Beta(2)-Microglobulin increased significantly (> 1 mg/l) in two patients with high S-F(-) relative to two of the 45 patients with S-F(-) below 40 micromol/l (P= 0.005). None of the patients developed clinically detectable renal dysfunction.

CONCLUSION

Smoking did not affect S-F(-) after sevoflurane anaesthesia. Glomerular dysfunction, seen as increased serum TATI, was noted in five women with S-F(-) above 40 micromol/l. Our results suggest that the renal toxic threshold of S-F(-) seems to be lower than the earlier reported value of 50 micromol/l.

Interpleural bupivacaine and intravenous oxycodone for pain treatment after thoracotomy in children

INTRODUCTION

The results of studies exploring the efficacy of interpleural analgesia in children post-thoracotomy have frequently been inconclusive. In this pilot study, we have evaluated the efficacy and safety of interpleural bupivacaine and intravenous (IV) oxycodone in pain treatment after thoracotomy in 10 generally healthy children, aged 10 months to 12 years, with patent ductus arteriosus who underwent thoracotomy.

METHODS

After surgery, all 10 children were given ibuprofen 10 mg/kg rectally every six hours. The first dose of interpleural bupivacaine (2 mg/kg) was given with epinephrine at the end of surgery, and thereafter plain bupivacaine (1 mg/kg) was given every two hours if the pain score was 4 or higher on an 11-point numeric rating scale (0 = no pain, 10 = worst possible pain). For rescue analgesia, children were provided oxycodone 0.1 mg/kg IV if pain was not relieved sufficiently with ibuprofen and bupivacaine. Vital signs, pain scores, and all adverse effects were monitored continuously for 24 hours.

RESULTS

All 10 children needed both interpleural bupivacaine and IV oxycodone. The number of bupivacaine doses ranged between three and 10 (mean = 6.1, SD = 2.3), and the number of oxycodone doses ranged between one and 12 (mean = 6.0, SD = 3.6). No cases of low respiratory rate or low peripheral oxygen saturation or any serious adverse events were recorded.

CONCLUSION

Scheduled nonopioid analgesic (ibuprofen) with interpleural bupivacaine did not provide sufficient analgesia for post-thoracotomy pain in young children. IV oxycodone was found to be an effective and safe opioid supplement to the pain regimen.

Cerebrospinal Fluid Distribution of Ketoprofen after Intravenous Administration in Young Children

OBJECTIVE

The purpose of this study was to evaluate the cerebrospinal fluid (CSF) distribution of an NSAID, ketoprofen, in children. Ketoprofen concentrations were determined from the CSF, plasma and protein-free plasma samples.

METHODS

Children (n = 21), aged 13-94 months, were given intravenous ketoprofen (1 mg/kg) prior to surgery under spinal anaesthesia. Single venous blood and CSF samples from each patient were collected simultaneously 7-67 minutes after the drug administration. Ketoprofen concentrations in the samples were determined using gas chromatography-mass spectrometry.

RESULTS

Ketoprofen entered the CSF and was detectable in all samples. However, CSF delivery was limited; the ratio of ketoprofen concentration in CSF to plasma remained below 0.006 at all times. Ketoprofen was highly bound (> 98%) to plasma proteins. The free ketoprofen fraction was not in equilibrium with the CSF, and no clear peak drug concentration in the CSF was observed.

CONCLUSION

This study shows that ketoprofen is able to enter the CSF of children, which enables central analgesic effects of ketoprofen. However, the slow distribution of ketoprofen into the CSF and the apparently low absolute concentrations has to be taken into account when central analgesic effects are desired.

High success rate and low incidence of headache and neurological symptoms with two spinal needle designs in children

BACKGROUND

In children, only a few trials have evaluated the use of spinal needles with special tip designs. In this study, we compared the success rate and incidence of post-dural puncture complaints of two small-gauge spinal needle designs used in children undergoing spinal anaesthesia (SA).

METHODS

Three hundred and three children aged 9 months to 17 years presenting for subumbilical surgery were randomly assigned to have a 26G Atraucan (n = 156) or 27G Whitacre (n = 147) spinal needle for SA. The number of attempts to obtain successful cerebrospinal fluid (CSF) return and the success rate of SA were recorded. The first week of recovery was recorded by a diary.

RESULTS

Both groups had a similar one-attempt success rate: 80% in the Atraucan group and 81% in the Whitacre group. Failure to obtain CSF occurred in one patient in the Atraucan group and in two patients in the Whitacre group. Paraesthesia was observed more commonly in the Whitacre group (10%) than in the Atraucan group (2%) (P = 0.004). The success rate of SA was 96%, with no differences between the two needles; one child was given general anaesthesia and 11 children (3%) a single dose of supplemental analgesia for the skin incision. Forty-one children (15%) developed a headache, 13 of which were classified as post-dural puncture headache (PDPH), seven cases (5%) in the Atraucan group and six (4%) in the Whitacre group; none of the children required a blood patch. Fifteen children (10%) in the Atraucan group and nine (7%) in the Whitacre group developed low back pain. Two children (1%) in the Atraucan group and four (3%) in the Whitacre group developed transient neurological symptoms (TNSs).

CONCLUSION

Both needles were associated with a high success rate and a low incidence of complaints.

Isobaric Ropivacaine 5 mg/mL for Spinal Anesthesia in Children

In this clinical trial, we evaluated the clinical effects of ropivacaine for spinal anesthesia in children. An open, prospective study was performed on 93 children, aged 1-17 yr, undergoing elective lower abdominal or lower limb surgery. A plain solution of ropivacaine 5 mg/mL at a dose of 0.5 mg/kg body weight (up to 20 mg) was administered via the L3-4 or L4-5 interspace with the patient in the lateral decubitus position. After injection, the patients were placed supine. The spread and duration of sensory analgesia and the degree of motor block were recorded. Satisfactory surgical anesthesia was achieved in 92 of the 93 children. Three children received general anesthesia; in one child spinal anesthesia failed, and in two cases surgery outlasted the duration of the sensory block. Four children received supplemental analgesia for skin incision. The mean highest level of sensory block was T6 (range, T2 to T12), and the mean time to the regression of sensory block to T10 was 96 min (range, 34-210 min). One child developed transient bradycardia and one hypotension. After discharge four children developed mild transient radiating neurologic symptoms and one epidural blood patch was performed for persistent position-dependent headache. We conclude that the block performance of intrathecal isobaric ropivacaine in children (>1 yr) is similar to that obtained in adults but the safety of the larger dose used in children warrants further studies.

Fluoride metabolism in smokers and non-smokers following enflurane anaesthesia

BACKGROUND

Inorganic fluoride is released by the metabolism of enflurane and the increased serum fluoride concentrations may impair renal function. Tobacco smoke consists of numerous reactive compounds that can either induce or inhibit drug metabolism. Studies on the interaction of smoking with anaesthetic drug metabolism and possible toxicity are warranted.

METHODS

Sixteen non-smoking and 17 smoking (>10 cigarettes day(-1)) generally healthy women undergoing elective gynaecological surgery were given 1 MAC (minimum alveolar concentration)-hour standardized anaesthesia with enflurane in oxygen-air mixture. The serum inorganic fluoride and renal function markers beta(2)-microglobulin, tumour-associated trypsin inhibitor (TATI) and serum creatinine were measured for 48 h.

RESULTS

The greatest inorganic fluoride concentration was between 8.4 and 21.0 (mean 13.8 (SD 3.4)) micromol litre(-1) in the non-smokers and between 8.6 and 38.0 (18.7 (7.0)) micromol litre(-1) in the smokers; the mean difference was 4.9 micromol litre(-1) (95% confidence interval (CI) 1.0-8.8, P<0.05). Serum beta(2)-microglobulin, TATI and creatinine were not increased. Serum inorganic fluoride concentrations were significantly greater in the smokers compared with the non- smokers 1, 2, 3 and 6 h after 1 MAC-hour inhalation with enflurane (P<0.05). Inorganic fluoride concentrations were still increased 24 h after anaesthesia in both groups. Urine beta(2)-microglobulin and TATI creatinine ratio remained at low values during the whole 48-h period in both groups.

CONCLUSIONS

Regular smoking is associated with an increase in serum inorganic fluoride concentration after anaesthesia with enflurane, but there are no signs of renal damage.

Clonidine provides opioid-sparing effect, stable hemodynamics, and renal integrity during laparoscopic cholecystectomy

BACKGROUND

Carbon dioxide pneumoperitoneum causes a hemodynamic stress response and decreases urine output because of an activated renin-angiotensin-aldosterone system (RAAS). Clonidine is a potent antihypertensive drug that suppresses RAAS.

METHODS

The effects of clonidine 4.5 mg/kg or saline on hemodynamics, neuroendocrine response, and renal parameters were compared in 30 healthy patients undergoing laparoscopic cholecystectomy.

RESULTS

Heart rate, arterial blood pressures, and plasma renin activity were lower during and after pneumoperitoneum in patients with clonidine. There were no differences in urine output, urine oxygen tension (reflecting medullary perfusion), or antidiuretic hormone between the groups. N-acetyl-b-D-glucosaminidase, a marker of proximal tubular damage, was minimally elevated after clonidine.

CONCLUSIONS

Clonidine enabled stable hemodynamics and prevented activation of RAAS seen as unchanged plasma renin activity. Clonidine may be beneficial during laparoscopy in patients with hypertension, cardiovascular, and/or renal diseases.

The effect of ketorolac and sevoflurane anesthesia on renal glomerular and tubular function

We assessed the renal effects of the combination of ketorolac and sevoflurane anesthesia by using sensitive and specific markers of renal proximal and distal tubular and glomerular function. Thirty women (ASA physical status I and II) undergoing breast surgery received either ketorolac 30 mg IM or saline at premedication, at the end, and 6 h after anesthesia maintained with sevoflurane. Peak levels of serum fluoride at 2 h after the end of anesthesia were 30.1 micromol/L (21.0-50.0 micromol/L) in the Ketorolac group and 33.3 micromol/L (13.0-38.0 micromol/L) in the Control group (mean and range, not significant). Urine alpha1-microglobulin indexed to urine creatinine was increased from 2 h after the start of anesthesia until the first postoperative day in the Ketorolac group (peak level, 0.8 +/- 0.4 mg/mmol; upper limit of normal, 0.7 mg/mmol) but did not change in the Control group. Urine glutathione-S-transferase (GST)-alpha indexed to urine creatinine (GST-alpha/creatinine) and GST-pi/creatinine were increased 2 h after anesthesia and returned to baseline values thereafter in both groups. There were no changes in serum cystatin C and urine kallikrein or urine output per hour between groups. The perioperative administration of ketorolac to healthy, well hydrated patients anesthetized with sevoflurane did not produce renal glomerular or tubular dysfunction.

IMPLICATIONS

Ketorolac 90 mg IM, given in divided doses over approximately 10 h to patients anesthetized with sevoflurane with a fresh gas flow rate of 4-6 L/min, did not result in clinically significant changes in renal glomerular or tubular function.

Ketorolac is not nephrotoxic in connection with sevoflurane anesthesia in patients undergoing breast surgery

Ketorolac, which may cause renal vasoconstriction by cyclooxygenase inhibition, is often administered to patients anesthetized with sevoflurane that is metabolized to inorganic fluoride (F(-)), another potential nephrotoxin. We assessed this possible interaction using urine N-acetyl-beta-D-glucosaminidase indexed to urinary creatinine (U-NAG/crea) as a marker of proximal tubular, beta2-microglobulin as a tubular, urine oxygen tension (P(u)O(2)) as a medullary, and erythropoietin as a marker of tubulointerstitial damage. Thirty women (ASA physical status I-II) undergoing breast surgery were included in our double-blinded study. They were allocated into two groups receiving either ketorolac 30 mg IM (Group K) or saline (Group C) at the time of premedication, at the end of, and 6 h after anesthesia maintained with sevoflurane. Urine output, U-NAG/crea, P(u)O(2,) serum creatinine, urea, and F(-) were assessed. Blood loss was larger in Group K (465 +/- 286 mL vs 240 +/- 149 mL, mean +/- SD, P < 0.05). The MAC-doses of sevoflurane were similar. U-NAG/crea increased during the first 2 h of anesthesia and serum F(-) peaked 2 h after the anesthesia without differences between the groups. There were no statistically significant changes in P(u)O(2), erythropoietin, beta2-microglobulin, serum creatinine, urea, or urine output during anesthesia or the recovery period in either group. Our results indicate that the kidneys are not affected by ketorolac administered in connection with sevoflurane anesthesia.

IMPLICATIONS

The different kinetics of N-acetyl-beta-D-glucosaminidase indexed to urinary creatinine and serum inorganic fluoride during and after sevoflurane anesthesia suggest that the observed mild renal tubular function deterioration is not caused by inorganic fluoride. Administration of ketorolac IM is therefore considered safe in adequately hydrated healthy adult patients given sevoflurane anesthesia.