Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0344307 (analgesia)
 28,200 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Whether morphine and ketamine induced cross-tolerance to some of their common pharmacological and biochemical effects, namely analgesia and enhancement of metabolites of dopamine (DA) in the striatum and limbic area of the rat was analysed. Ketamine was given at the dose of 100 mg/kg, twice a day for 8 days. After this treatment, a challenge dose of morphine (15 mg/kg, i.p.) still induced analgesia comparable to that induced by morphine alone, showing no cross-tolerance to this effect. In contrast, the challenge dose of morphine given to ketamine-tolerant rats no longer enhanced metabolism of DA, indicating the appearance of cross-tolerance to this effect. A high degree of tolerance to morphine was obtained after the subcutaneous implantation of rats with pellets of morphine; a challenge dose of ketamine to morphine-tolerant rats induced marked analgesia, with no cross-tolerance to this pharmacological effect, while cross-tolerance was present to the biochemical effect. The existence of a high degree of reciprocal cross-tolerance in both areas and on both metabolites of DA is consistent with the hypothesis of action at a common receptor; the lack of cross-tolerance to the analgesic effect indicates that analgesia is achieved by a different mechanism for the two drugs.
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PMID:Cross tolerance between ketamine and morphine to some pharmacological and biochemical effects. 402 68

Ketamine 25 mg/kg was administered to five foxhounds by the intravenous, intramuscular or rectal route. Plasma concentrations were measured by gas-chromatography and analgesia was tested by two techniques. Intravenous application gave reliable analgesia and well reproducible plasma levels in all subjects. Distribution and elimination half lives were found to be 6 min and 55 min, respectively. Intramuscular injection resulted in peak-plasma levels around the twentieth minute, elimination half life was fifty-two minutes, bioavailability 90%. Analgesia proved satisfactory in four out of the five subjects and lasted longer than after intravenous injection. The rectal route produced a wide range of peak-plasma levels, the average peak appearing after 40 min. We found an elimination halflife of 43 min and a bioavailability of 30%. Analgesia was poor in four out of the five subjects. The low plasma levels following rectal application are due to the poor bioavailability and this appears to be the reason for the unsatisfactory results with this route of administration. Bioavailability depends on the site of application (drainage mainly through the vena cava or portal vein) and the pH of the rectum.
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PMID:[Comparative study of analgesia and plasma level following rectal, intramuscular and intravenous administration of ketamine]. 403 84

Ketamine, 40 ml 0.5% solution, was used in the technique of intravenous regional anaesthesia in 14 patients undergoing upper limb surgery. Satisfactory analgesia was obtained in 12 of the patients. The method is limited by the fact that all patients became unconscious within a few minutes of tourniquet release, and that this could not be prevented by naloxone.
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PMID:Intravenous regional anaesthesia with ketamine. 405 Nov 56

1 The interaction of naloxone with various anaesthetics was studied both in vivo and in vitro.2 Naloxone (10 mg/kg) did not significantly alter the anaesthetic duration of halothane, diethylether, ketamine, pentobarbitone or Althesin.3 Naloxone (10 mg/kg) reduced the analgesic activity of nitrous oxide, ketamine and morphine in the rat tail-flick test. With the exception of pentobarbitone and Althesin, the other anaesthetic agents also induced analgesia but were not antagonized by naloxone.4 Specific [(3)H]-dihydromorphine binding was displaced by the opiates naloxone (IC(50) = 7.6 nm), methionine-enkephalin (Met-enkephalin, IC(50) = 40 nm) and morphine (IC(50) = 54 nm). Similarly, displacement was observed with xylazine (IC(50) = 9 mum), ketamine (IC(50) = 130 mum) and Althesin (IC(50) = 150 mum); other anaesthetics agents tested were inactive in mm concentrations.5 Ketamine (IC(50) = 200 mum) and xylazine (IC(50) = 9.5 mum) were also capable of displacing specific [(3)H]-D-Ala(2)-enkephalin (D-Leu) binding, as were morphine (IC(50) = 95 nm) and Met-enkephalin (IC(50) = 40 nm).6 On the stimulated guinea-pig ileum, Met-enkephalin and morphine inhibited the contractions, the IC(50) values were 30 nm and 50 nm respectively. The anaesthetics ketamine (IC(50) = 10 mum) and Althesin (IC(50) = 8 mum) were active. Xylazine (IC(50) = 12 nm) exhibited considerable potency in inhibiting the contractions on this preparation. Naloxone 0.5 mum produced a 1000 fold shift in the opiate dose-response curve but the anaesthetic responses showed only slight sensitivity to antagonism by naloxone.7 The activity of Althesin was found to be due to the vehicle in which this anaesthetic is solubilised.8 Whilst several anaesthetic agents showed analgesic activity, specific dihydromorphine binding displacement or guinea pig ileum inhibiting activity, these effects showed variable sensitivity to naloxone.
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PMID:Opiate-like analgesic activity in general anaesthetics. 611 17

Ketamine, an anesthetic agent endowed with several morphine-like effects, failed to displace 3H-dihydromorphine or 3H-methionine-enkephalin from opiate receptors in the rat brain synaptosomal-mitochondrial membrane preparations. Furthermore, ketamine-induced analgesia in rats was not antagonized by naloxone, suggesting that this effect is not mediated by opiate receptors.
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PMID:Failure of ketamine to interact with opiate receptors. 624 94

Anesthetic (120 and 160 mg/kg. i.p.) and subanesthetic (80 mg/kg) doses of ketamine HCl were found to prevent completely the depletion of whole brain serotonin (5-HT) by p-chloramphetamine (PCA). Furthermore, ketamine HCl (160 mg/kg) completely blocked the depletion of 5-HT by PCA in every individual brain region studied (Midbrain-thalamus, hypothalamus, striatum, hippocampus and cortex). Administration of ketamine alone had no effect on brain 5-HT levels. Nialamide (a monoamine oxidase (MAO) inhibitor) and fluoxetine (a selective 5-HT uptake inhibitor) also prevented the depletion of 5-HT by PCA. However, of these three agents, only nialamide prevented the depletion of 5-HT by reserpine. These results suggest that ketamine blocks PCA-induced 5-HT depletion by inhibiting 5-HT uptake and not by inhibiting MAO. Ketamine only weakly affected either [3H]5-HT or [3H]spiroperidol binding to 5-HT1 and 5-HT2 receptors respectively even at concentrations as high as 1 mM. These data support the contention that the primary direct effect of ketamine on serotonergic systems is the blockade of 5-HT uptake and that blockade of 5-HT uptake may mediate some of the behavioral effects of ketamine, such as analgesia.
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PMID:Ketamine inhibits serotonin uptake in vivo. 646 Sep 44

The following three regimens of anesthesia in mice were compared: (1) Ketamine 100 mg--xylazine 5 mg/kg b.wt. i.m., (2) pentobarbitone 50 mg/kg b.wt. i.p., and (3) carfentanyl 0.003 mg--etomidate 15 mg/kg b.wt. i.m. For these dosage rates the respiratory variables, i.e., respiratory rate, paO2, paCO2, pHa, BEa, HCO-3a, and the circulatory parameters, i.e., heart rate, mean arterial pressure and hematocrit, were determined during the conscious state, during surgical anesthesia, and at waking time. With ketamine and xylazine, the respiration was moderately decreased whereas the cardiovascular system was strongly depressed. Pentobarbitone induced a high respiratory depression but a lesser degree of circulatory depression. Analgesia was inadequate. Although there was a moderate respiratory and circulatory depression during anesthesia with carfentanyl and etomidate the drug-induced excitation and muscle spasms do not recommend this anesthetic combination for mice. Of these three methods, the combination of ketamine and xylazine is considered the most reliable for anesthesia of mice.
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PMID:A comparative study with various anesthetics in mice (pentobarbitone, ketamine-xylazine, carfentanyl-etomidate). 647 5

Intrathecal ketamine, which has not previously been described in man, has been administered to 16 patients with war injuries of the lower limbs. The first five received varying doses from 5 to 50 mg in a volume of 3 ml of 5% dextrose, to determine a dose-response curve (Group 1). The optimal dose was then administered to a further 11 patients who received ketamine 50 mg in a volume of 3 ml in 5% dextrose with the addition of adrenaline 0.1 mg (Group 2). A distinct sensory level was obtained in all patients. In Group 2, nine of the eleven patients obtained satisfactory surgical analgesia and two required supplementation with local anaesthetic. Central effects (drowsiness, dizziness, and nystagmus) also occurred in nine patients, but they remained conscious throughout; one patient experienced no central effects, and one patient developed dissociative anaesthesia. Central effects were more intense the higher level of block. There were no significant changes in mean systolic arterial blood pressure, pulse, or respiratory rates. Surgical analgesia for the blocked dermatomes lasted for a mean of 58 minutes (range 45-90), and recovery was complete and uncomplicated; mild generalised analgesia persisted for a further one to three hours following return of sensation. Ketamine alone did not produce motor block, but addition of adrenaline resulted in complete motor block, and may have intensified sensory blockade. Motor loss persisted for the same duration as surgical analgesia. Adrenaline neither delayed the onset of central effects, nor reduced their intensity.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Intrathecal ketamine for war surgery. A preliminary study under field conditions. 649 99

Ketamine was used on 80 occasions to induce anaesthesia in 77 animals. Xylazine premedication was used alone on 75 occasions, in conjunction with methadone once, in conjunction with methadone and acepromazine once and, on three occasions, methadone and acepromazine only were used. Anaesthesia was maintained in seven cases with halothane and oxygen. Premedication with xylazine 5 mins previously or concurrently with ketamine gave similar results but an interval of more than 5 mins between the drugs produced less deep anaesthesia and this protocol is, therefore, not advised. Induction and recovery were judged to be good in 82 per cent and 78 per cent of cases, respectively, and analgesia and muscle relaxation were judged as adequate in 79 per cent of cases.
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PMID:A field trial of ketamine anaesthesia in the horse. 673 82

Ketamine HCl was evaluated as a general anesthetic alone and in combination with chlorpromazine HCl on the basis of sedative and cardiovascular effects in 40 buffalo calves (Bubalus bubalis). Calves were rapidly immobilized after IV administration of ketamine HCl (2 mg/kg of body weight). Preanesthetic treatment of calves with chlorpromazine increased the duration of analgesia, standing and recovery times, and the degree of muscle relaxation. The duration and degree of analgesia obtained were adequate for short-term surgical procedures. All animals survived the anesthetic trials, and recovery was smooth and rapid. Hemodynamic studies revealed increases in heart rate, mean blood pressure, cardiac output, and peripheral vascular resistance during maximal depth of anesthesia. The venous pressure decreased initially and then increased progressively. Increases and decreases in these measurements were transient, and the measurements returned to base-line values within 30 minutes after ketamine administration. Definite trends were not seen on ECG tracings, except for elevations and depressions of ST segment, T-wave changes, and wandering pacemaker in a few animals, and sinus tachycardia in all animals.
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PMID:Anesthetic and hemodynamic effects of ketamine hydrochloride in buffalo calves (Bubalus bubalis). 709 52


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