Biomedical subjects

Dirk G Snijdelaar

Publications and source records attributed to Dirk G Snijdelaar.

4 recordsLinked to original sources

PubMed2005

Effects of pre-treatment with amantadine on morphine induced antinociception during second phase formalin responses in rats.

The clinically available NMDA-receptor antagonist drug, amantadine, has been shown to result in morphine sparing effects in humans after surgery. However, no data are available to describe the exact form of interaction. The present study aims to profile the possible effects of amantadine (0, 12.5, 25 or 50 mgkg(-1) i.p.) pre-treatment on morphine (0, 0.63, 1.25, 2.5 or 5 mgkg(-1) s.c.) induced antinociception in rats. The (automated) formalin test (5% formalin, 50 microl) was used to assess if amantadine enhances the antinociceptive activity of morphine. Possible motor impairment was assessed with a rotarod test. Morphine was measured in serum of amantadine or vehicle treated rats to search for possible pharmacokinetic interactions between amantadine and morphine. Isobolographic analysis provided evidence for a synergistic interaction between amantadine and morphine in the second phase of the formalin test. No evidence was found to indicate that amantadine induced motor impairment at the doses potentiating morphine during the second phase of the formalin test. There was no evidence for a pharmacokinetic interaction between amantadine and morphine. Since, the second phase of the formalin test is dependent on activation of the NMDA receptor system it is concluded that an antagonistic activity of amantadine at the NMDA receptor most likely contributes to the synergistic interaction observed between amantadine and morphine in rats.

Amantadine↗

PubMed2004

Pre-emptive analgesia using intravenous fentanyl plus low-dose ketamine for radical prostatectomy under general anesthesia does not produce short-term or long-term reductions in pain or analgesic use.

The aim of the study was to evaluate post-operative pain and analgesic use after pre-operative or post-incisional i.v. fentanyl plus low dose i.v. ketamine vs. a standard treatment receiving i.v. fentanyl but not ketamine. Men undergoing radical prostatectomy under general anesthesia were randomly assigned in a double-blinded manner to one of three groups. Patients received i.v. fentanyl before incision followed by an i.v. bolus dose (0.2 ml kg(-1)) and an i.v. infusion (0.0025 ml kg(-1)min(-1)) of 1 mg ml(-1) ketamine (group 1) or normal saline (groups 2 and 3). Seventy minutes after incision, patients received i.v. fentanyl followed by an i.v. bolus dose (0.2 ml kg(-1)) and an i.v. infusion (0.0025 ml kg(-1)min(-1)) of saline (groups 1 and 3) or ketamine (group 2). Pain, von Frey pain thresholds, and cumulative morphine consumption using patient-controlled analgesia (PCA) were assessed up to 72 h after surgery. 143 patients completed the study (group 1, n = 47, group 2, n = 50, group 3, n = 46). Cumulative PCA morphine (mean+/-SD) did not differ significantly among groups (group 1, 92.3+/-45.9 mg; group 2, 107.2+/-58.4 mg; group 3, 103.6+/-50.4 mg; P = 0.08 for groups 1 vs. 2, and groups 1 vs. 3). On day 3, the hourly rate (mean+/-SEM) of morphine consumption was significantly lower (p < 0.0009) in group 1 (0.61+/-0.013 mg h(-1)) than group 2 (0.86+/-0.011 mg h(-1)) and group 3 (0.89+/-0.008 mg h(-1)). Pain scores and von Frey pain thresholds did not differ significantly among groups. Two-week and 6-month follow-ups did not reveal significant group differences in pain incidence, intensity, disability or mental health. Pre-operative, low-dose administration of i.v. ketamine did not result in a clinically meaningful reduction in pain or morphine consumption when compared with post-incisional administration of ketamine or a saline control condition.

Aged↗

PubMed2004

Effects of perioperative oral amantadine on postoperative pain and morphine consumption in patients after radical prostatectomy: results of a preliminary study.

BACKGROUND: Amantadine is known to be a noncompetitive N-methyl-D-aspartate receptor antagonist and may be useful in preventing postoperative central sensitization, acute opioid tolerance, and opioid-induced hyperalgesia, thereby decreasing pain and analgesic requirements. The aim of this pilot study was to evaluate the effects of perioperative oral amantadine on postoperative pain and analgesic consumption. METHODS: Twenty-four patients scheduled to undergo radical prostatectomy were given oral amantadine before and after surgery in a randomized, double-blind, placebo-controlled manner. After surgery, patients received intravenous patient-controlled analgesia with morphine for 48 h. Wound pain intensity, sensitivity to mechanical pressure around the surgical wound, and incidence of bladder spasm pain were assessed. Blood samples were drawn for analysis of amantadine, morphine, and the morphine metabolites. Adverse effects and patient satisfaction were assessed. RESULTS: The cumulative morphine consumption was significantly lower in the amantadine group at all time points (except at 48 h), amounting to a 32% reduction over the 48-h period. Forty-eight hours after surgery, visual analog pain scores to pressure applied near the wound were significantly lower in the amantadine group than in the placebo group. In addition, the number of patients reporting bladder spasm pain was significantly lower in the amantadine group. Plasma concentration of morphine-3-glucuronide was significantly lower at the end of surgery in the amantadine group. Pharmacokinetic analyses showed that the plasma clearance of morphine at 22-24 h after surgery was also significantly lower in the amantadine group. CONCLUSION: The results suggest that perioperative oral amantadine reduces postoperative opioid consumption by pharmacokinetic mechanisms, although additional pharmacodynamic interactions may also be involved.

Adolescent↗

PubMedDate not supplied

Methadone for phantom limb pain.

OBJECTIVE: The objective of this case series was to determine if severe phantom limb pain could be reduced with oral methadone. DESIGN: Four cases of phantom limb pain refractory to multiple treatment modalities were treated with oral methadone. SETTING: Pain clinic at a major university medical center. PATIENTS: Four patients with severe, intractable phantom limb pain. INTERVENTION: Oral methadone was administered, starting with a low dose of 2 to 5 mg twice a day or three times a day and slowly titrated upward to achieve pain relief. OUTCOME MEASURES: Repeated administration of a visual analog scale for pain. RESULTS AND CONCLUSIONS: Administration of oral methadone may be of value in the treatment of phantom limb pain; controlled clinical trials would be appropriate to verify this observation.

Administration, Oral↗