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Biomedical subjects

L F Gram

Publications and source records attributed to L F Gram.

At least 73 records · Page 4Linked to original sources
PubMed1992

The effect of quinidine on the analgesic effect of codeine.

We have studied the hypoalgesic effect of codeine (100 mg) after blocking the hepatic O-demethylation of codeine to morphine via the sparteine oxygenase (CYP2D6) by quinidine (200 mg). The study was performed in 16 extensive metabolizers of sparteine, using a double-blind, randomized, four-way, cross-over design. The treatments given at 3 h intervals during the four sessions were placebo/placebo, quinidine/placebo, placebo/codeine, and quinidine/codeine. We measured pinprick pain and pain tolerance thresholds to high energy argon laser stimuli before and 1, 2, and 3 h after codeine or placebo. After codeine and placebo, the peak plasma concentration of morphine was 6-62 (median 18) nmol.l-1. When quinidine pre-treatment was given, no morphine could be detected (less than 4 nmol.l-1) after codeine. The pin-prick pain thresholds were significantly increased after placebo/codeine, but not after quinidine/codeine compared with placebo/placebo. Both placebo/codeine and quinidine/codeine increased pain tolerance thresholds significantly. Quinidine/codeine and quinidine/placebo did not differ significantly for either pin-prick or tolerance pain thresholds. These results are compatible with local CYP2D6 mediated formation of morphine in the brain, not being blocked by quinidine. Alternatively, a hypoalgesic effect of quinidine might have confounded the results.

Adult↗
PubMed1992

Steady-state plasma levels of clomipramine and its metabolites: impact of the sparteine/debrisoquine oxidation polymorphism. Danish University Antidepressant Group.

After an initial placebo week, 37 depressed inpatients were treated with the fixed dose of 75 mg clomipramine b.d. A sparteine test was carried out during the placebo period and again during the second week of active therapy. Blood for drug assay was collected at the end of the inter-dose interval in the (morning) at weekly intervals. Clomipramine and four metabolites (desmethylclomipramine, didesmethylclomipramine, 8-hydroxyclomipramine, and 8-hydroxydesmethylclomipramine) in plasma were assayed by reversed phase HPLC. The clomipramine and desmethylclomipramine steady-state plasma levels varied by factors of 11 and 9, respectively, and the clomipramine/8-hydroxyclomipramine and desmethylclomipramine/8-hydroxydesmethylclomipramine ratios both varied by 7-fold. During the placebo week, 36 patients were phenotyped as extensive metabolizers (EM) (metabolic ratio, MR, 0.1-2.0), and one patient was phenotyped as a poor metabolizer (PM) (MR > 300). During clomipramine treatment, one patient changed phenotype from EM to PM (MR = 140). In the EM, the median of the MR increased from 0.4 to 2.3. There was a statistically significant correlation between the MR before and during clomipramine treatment, even when the PM was excluded. Neither the steady-state plasma clomipramine levels nor the clomipramine/desmethylclomipramine ratios showed a significant correlation with the MR. In contrast, the desmethylclomipramine and didesmethylclomipramine steady-state levels and the desmethylclomipramine/8-hydroxydesmethylclomipramine and clomipramine/8-hydroxyclomipramine ratios showed a significant positive correlation with the MR. The PM had the highest steady-state plasma desmethylclomipramine level and the highest desmethylclomipramine/8-hydroxydesmethylclomipramine ratio. These correlation coefficients (rs) were generally increased when the correlation analyses were based on the MR obtained during clomipramine treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Benzodiazepine-induced sedation and cortisol suppression. A placebo-controlled comparison of oxazepam and nitrazepam in healthy male volunteers.

The sedative and cortisol suppressing properties of oxazepam (45 and 60 mg) and nitrazepam (10 and 15 mg) were examined in eight healthy male subjects. The most clear differences between oxazepam and nitrazepam were those seen with respect to the time course and until maximal effect (Tmax) of the different measurements. Nitrazepam showed maximal sedation after 1 h, maximal benzodiazepine level (RRA), and reaction time prolongation after 2 h, and maximal cortisol suppression after 3 h. Oxazepam showed maximal sedation after 2 h, maximal benzodiazepine levels, reaction time prolongation and cortisol suppression after 3 h. After administration of oxazepam (both doses) a transient return to baseline levels of cortisol was demonstrated. Whereas the degree of sedation correlated significantly within drug groups with the concurrent benzodiazepine levels, the Tmax of sedation was recorded 1 h earlier than the peak blood concentration (RRA) for both nitrazepam and oxazepam. The time course for cortisol suppression for the two compounds differed clearly from the other measurements and was not related to the peak blood concentration.

Affect↗
PubMed1992

Lack of effect of mianserin on the symptoms of diabetic neuropathy.

The effect of the non-tricyclic antidepressant mianserin on symptoms of diabetic neuropathy has been studied in 18 patients in a double-blind, cross-over study with imipramine as a positive control. The patients were treated with placebo, mianserin, and imipramine, each for two weeks, in randomized order, with 1-3 weeks between the treatments. The symptoms were assessed by observer and self-rating scales. Mianserin was given in the fixed dosage of 60 mg per day, whereas the dose of imipramine was adjusted to yield the optimal plasma concentration of imipramine plus desipramine of 400-600 nmol.l-1. The mianserin plus desmethylmianserin plasma concentration ranged from 85 to 850 nmol.l-1, with the highest concentration in a patient who was a poor metabolizer of both sparteine and mephenytoin. The symptoms of neuropathy were significantly reduced during imipramine treatment, although somewhat less than in earlier studies. In contrast, mianserin produced no change in symptoms in comparison with placebo. As there was no evidence that higher mianserin (plus metabolite) steady-state concentrations were associated with a more favourable effect, the negative outcome appeared not to be related to underdosing with mianserin. In contrast to drugs with documented effects on the symptoms of diabetic neuropathy, mianserin has a very weak or no inhibitory effect on 5-HT and noradrenaline reuptake and this may explain its poor clinical effect.

Adult↗
PubMed1992

The selective serotonin reuptake inhibitor citalopram relieves the symptoms of diabetic neuropathy.

The effect of the selective serotonin reuptake inhibitor citalopram on diabetic neuropathy symptoms was examined in a double-blind, placebo-controlled, crossover study for two 3-week periods. Citalopram was given as a fixed dose of 40 mg/day. Data from 15 patients could be included in the statistical analysis. Citalopram significantly relieved the symptoms of neuropathy as measured by both observer- and self-rating in comparison with placebo. The steady-state plasma concentration of citalopram was 10 to 890 nmol/L. There was no significant relationship between the plasma concentration of citalopram and the effect of treatment as measured by observer- or self-rating. Two of 17 patients, both receiving citalopram, left the study because of side effects (nausea and vomiting or gastric upset and diarrhea). Side-effect ratings were significantly higher during administration of citalopram than during administration of placebo, but citalopram was generally well tolerated. Compared with earlier results obtained with imipramine administered on the basis of plasma level monitoring, citalopram appeared to be less effective, but seemed to be better tolerated.

Adult↗
PubMed1992

The relationship between paroxetine and the sparteine oxidation polymorphism.

The relationship between the selective serotonin reuptake inhibitor paroxetine and the sparteine oxidation polymorphism was investigated in a combined single-dose (30 mg) and steady-state (30 mg/day for 2 weeks) study including a panel of nine extensive metabolizers and eight poor metabolizers of sparteine. The median area under the plasma concentration-time curve (AUC) after the first paroxetine dose was about seven times higher in poor metabolizers than in extensive metabolizers (3910 versus 550 nmol.hr/L), whereas at steady state the median AUCss tau interphenotype difference was only twofold (4410 versus 2550 nmol.hr/L). Plasma half-life and steady-state plasma concentration were significantly longer and higher, respectively, in poor metabolizers than in extensive metabolizers (41 versus 16 hours and 151 versus 81 nmol/L). Paroxetine pharmacokinetics were linear in poor metabolizers and nonlinear only in extensive metabolizers. Sparteine metabolic ratio (MR = 12 hour urinary ratio of sparteine/dehydrosparteine), increased during treatment with paroxetine in subjects who were extensive metabolizers, and after 14 days treatment two extensive metabolizers were phenotyped as poor metabolizers and the remaining extensive metabolizers were changed into extremely slow extensive metabolizers with sparteine MRs of 5.7 to 16.5. The inhibition of sparteine metabolism was rapidly reversed after cessation of paroxetine administration. In the poor metabolizers there were no significant changes in MRs during the study. It is concluded that paroxetine and sparteine metabolism cosegregates, but the interphenotype difference in metabolism was less prominent at steady state than after a single dose, presumably because of saturation of the sparteine oxygenase (CYP2D6) in subjects who were extensive metabolizers. Paroxetine is a potent inhibitor of sparteine oxidation by CYP2D6 in vivo.

Adult↗
PubMed1992

Pharmacokinetics of the selective serotonin reuptake inhibitor paroxetine: nonlinearity and relation to the sparteine oxidation polymorphism.

Steady-state plasma concentrations of paroxetine were studied at five or more paroxetine dose levels (10 to 70 mg/day) in each of 13 extensive metabolizers of sparteine and at three or four dose levels (10 to 40 mg/day) in each of three poor metabolizers of sparteine, all treated for diabetic neuropathy symptoms. On a dose of 30 mg/day there was a 25-fold variation in steady-state concentrations (25 to 670 nmol/L). The upper extreme of this variation was made up by the poor metabolizers of sparteine and the lower extreme by some fast extensive metabolizers. Further, within the extensive metabolizer group, steady-state levels showed a significant, positive correlation with sparteine metabolic ratio at all dose levels. On increasing doses, a disproportionate increase in plasma drug levels was observed in the majority of patients. In nearly all extensive metabolizers the concentration-dose data were best described by a pharmacokinetic model assuming elimination by at least two kinetically distinct processes, one a high-affinity saturable process and one a low-affinity linear process. Estimates of clearance at low drug levels of the high-affinity process showed a significant negative correlation with the sparteine metabolic ratio. Clearance of the low-affinity process was not related to the metabolic ratio and was of the same magnitude in extensive and poor metabolizers. The data thus confirmed that the metabolism of paroxetine and sparteine cosegregates and indicated that the enzyme responsible for a high-affinity saturable paroxetine elimination process is identical with CYP2D6, the source of the sparteine oxidation polymorphism.

Adult↗
PubMed1992

Plasma beta-endorphin is not affected by treatment with imipramine or paroxetine in patients with diabetic neuropathy symptoms.

To determine the possible role of endogenous opioid peptides in the action of imipramine and paroxetine in painful diabetic neuropathy, beta-endorphin concentrations in plasma were measured in 20 patients during a double-blind, placebo-controlled randomized three-way crossover trial. Despite a significant reduction in neuropathy symptoms during both imipramine and paroxetine treatment, the beta-endorphin level was unaltered throughout the study. The plasma concentration of beta-endorphin was not related to plasma drug concentrations. Thus, this study does not provide evidence of a role of endogenous opioid peptides in the mechanism of action of imipramine and paroxetine in painful diabetic neuropathy.

Adult↗
PubMed1992

Drug related admissions to medical wards: a population based survey.

1. In total 1999 consecutive admissions to six medical wards were subjected to a prospective high-intensity drug event monitoring scheme to assess the extent and pattern of admissions caused by adverse drug reactions (ADRs) or dose related therapeutic failures (TF), in a population-based design. The wards were sub-specialised in general medicine, geriatrics, endocrinology, cardiology, respiratory medicine and gastroenterology. 2. Considering definite, probable and possible drug events, the prevalence of drug related hospital admissions was 11.4% of which 8.4% were caused by ADRs and 3.0% by TFs. There were large inter-department differences. 3. The six classes of drugs most frequently involved in admissions caused by ADRs were anti-rheumatics and analgesics (27%), cardiovascular drugs (23%), psychotropic drugs (14%), anti-diabetics (12%), antibiotics (7%), and corticosteroids (5%). Noncompliance accounted for 66% of the TFs with diuretics and anti-asthmatics most frequently involved. 4. The pattern of drugs involved in ADRs was compared with the regional drug sales statistics. Drugs with a particularly high rate of ADR related admissions per unit dispensed were nitrofurantoin and insulin (617 and 182 admissions per 1,000,000 defined daily doses), while low rates were seen for diuretics and benzodiazepines (10 and 7 admissions per 1,000,000 defined daily doses). Confidence intervals were wide. 5. Patients who had their therapy prescribed by a hospital doctor had a slightly higher prevalence of drug events than those who were treated by a general practitioner (12.6% vs 11.8%). The reverse applied for drug events assessed as avoidable (3.3% vs 4.6%). Although these differences were not statistically significant, it may suggest general practitioners as the appropriate target for interventive measures.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Drug-related illness as a cause of admission to a department of respiratory medicine.

Three hundred and thirteen consecutive admissions to a department of respiratory medicine were evaluated in a prospective high-intensity monitoring scheme concerning adverse drug reactions or dose-related therapeutic failures as the contributing or sole cause of hospital admission. Eleven patients [3.5%, 95% confidence interval (CI) 2.0-6.2] were admitted because of adverse drug reactions. Only 3 of these patients manifested respiratory symptoms, while the remainder had various intercurrent nonpulmonary problems and were well known in the outpatient clinic, e.g. asthma or cancer patients. It is concluded that adverse drug reactions requiring admission rarely present as respiratory symptoms. Fourteen patient (4.5%, CI 2.7-7.4) were admitted because of dose-related therapeutic failures in all cases, except 2 with respiratory symptoms. Half of these were due to noncompliance. Analysis of theophylline samples taken on admission from 46 patients showed 25 (54%) to have concentrations below the therapeutic range of 55-110 microM, but contributed little to the identification of noncompliant patients. Eighty-three percent of the drug events were found to have been unavoidable. Nine patients admitted with acute asthma did not receive corticosteroids prior to admission (2.9%), all of which had therapy prescribed in general practice. The present study showed a comparatively low and hardly affectable prevalence of admissions caused by adverse drug reactions and dose-related therapeutic failure. However, therapeutic failure due to inappropriate choice of asthma medication, which was not included in this estimate, may be an important avoidable cause of admissions.

Adverse Drug Reaction Reporting Systems↗
PubMed1991

The mephenytoin oxidation polymorphism is partially responsible for the N-demethylation of imipramine.

The metabolism of imipramine in six poor metabolizers of mephenytoin was compared with the metabolism of 16 extensive metabolizers of mephenytoin from an earlier study. Each subject was given single doses of 100 mg imipramine hydrochloride and 100 mg desipramine hydrochloride on separate occasions. Imipramine demethylation clearance was 0.74 L.min-1 (mean; range, 0.31-1.24) in poor metabolizers of mephenytoin compared with 1.43 L.min-1 (mean; range, 0.61-3.81) in extensive metabolizers of mephenytoin (p = 0.01, Mann-Whitney U test). It has previously been shown that the imipramine clearance by way of other pathways and desipramine oral clearance, both largely representing 2-hydroxylation, are considerably lower in poor metabolizers of sparteine than in extensive metabolizers of sparteine. In contrast, five subjects who were poor metabolizers of mephenytoin and extensive metabolizers of sparteine and a control group of 11 subjects who were extensive metabolizers of mephenytoin and sparteine showed no statistically significant difference with regard to these parameters. One subject who was a poor metabolizer of mephenytoin and sparteine had the lowest imipramine oral clearance of all 22 subjects studied. In conclusion, this and an earlier study show that the oxidation of imipramine is mediated by means of two different polymorphic P450 isozymes, 2-hydroxylation by way of the sparteine oxygenase (P450IID6) and demethylation by way of the mephenytoin oxygenase (P450IIC8).

Adult↗
PubMed1991

Sparteine and mephenytoin oxidation: genetic polymorphisms in east and west Greenland.

The oxidation of sparteine and mephenytoin was examined in a group of subjects living in Greenland: 300 in East Greenland and 171 in West Greenland. The distribution of the ratio between the chromatographic peak areas of S- and R-mephenytoin in the urine, the S/R ratio was clearly bimodal in both populations. Thus 9.3% of the East Greenlanders had S/R ratios of 0.9 or more and were phenotyped as poor metabolizers of mephenytoin. In the West Greenlanders, 2.9% of the sample had S/R ratios of 0.90 or more and were accordingly phenotyped as poor metabolizers. The intraethnic difference with regard to the frequency of the mephenytoin poor metabolizer is probably attributable in part to a much higher proportion of admixed Caucasian genes in the West Greenlanders than in the East Greenlanders. In both the East and the West Greenlanders, the sparteine metabolic ratio displayed marked interindividual differences without a clear bimodal distribution. Poor metabolizers arbitrarily defined as subjects with an metabolic ratio of 20 or more made up 3.3% of the East Greenlanders and 2.3% of the West Greenlanders, but the difference between the two groups was not statistically significant.

Adolescent↗