Depression scores following migraine treatment in patients attending a specialized center for headache and neurology

OBJECTIVE

To determine the changes in clinical characteristics and depression levels among patients following treatment for migraine.

BACKGROUND

Epidemiologic studies have provided consistent evidence regarding an association between migraine and depression. In Puerto Rico, however, migraine has not yet been systematically investigated.

METHODS

A chart review of 144 Puerto Rican patients who presented with migraine, diagnosed according to the International Headache Society criteria, and depression over a 2-year period was performed. The level of depression, before and after migraine treatment, was evaluated using the Zung Self-rating Depression Scale.

RESULTS

The mean age of patients was 37.0 +/- 14.4 years; 77.1% were women. More than half (52.8%) reported severe headache and 56.9% reported a monthly frequency of five attacks or more. Nearly 9% were using antidepressant therapy and 8% were under psychiatric treatment. The mean Zung index score at baseline was 50.6 +/- 10.9. Following treatment with triptans, the intensity and frequency of migraine and the Zung index score decreased significantly (P<.00001). A trend for a greater reduction in Zung index scores among patients receiving triptan medications for more than a year was demonstrated (P =.07).

CONCLUSIONS

These results indicate that migraine treatment with triptans appears to be effective in decreasing the headache frequency and intensity, and depression levels, independent of antidepressant medication use or psychiatric treatment.

A novel role of neuregulin in skeletal muscle. Neuregulin stimulates glucose uptake, glucose transporter translocation, and transporter expression in muscle cells

Neuregulins regulate the expression of acetylcholine receptor genes and induce development of the neuromuscular junction in muscle. In studying whether neuregulins regulate glucose uptake in muscle, we analyzed the effect of a recombinant neuregulin, (r)heregulin-beta1-(177-244) (HRG), on L6E9 muscle cells, which express the neuregulin receptors ErbB2 and ErbB3. L6E9 responded acutely to HRG by a time- and concentration-dependent stimulation of 2-deoxyglucose uptake. HRG-induced stimulation of glucose transport was additive to the effect of insulin. The acute stimulation of the glucose transport induced by HRG was a consequence of the translocation of GLUT4, GLUT1, and GLUT3 glucose carriers to the cell surface. The effect of HRG on glucose transport was dependent on phosphatidylinositol 3-kinase activity. HRG also stimulated glucose transport in the incubated soleus muscle and was additive to the effect of insulin. Chronic exposure of L6E9 cells to HRG potentiated myogenic differentiation, and under these conditions, glucose transport was also stimulated. The activation of glucose transport after chronic HRG exposure was due to enhanced cell content of GLUT1 and GLUT3 and to increased abundance of these carriers at the plasma membrane. However, under these conditions, GLUT4 expression was markedly down-regulated. Muscle denervation is associated with GLUT1 induction and GLUT4 repression. In this connection, muscle denervation caused a marked increase in the content of ErbB2 and ErbB3 receptors, which occurred in the absence of alterations in neuregulin mRNA levels. This fact suggests that neuregulins regulate glucose transporter expression in denervated muscle. We conclude that neuregulins regulate glucose uptake in L6E9 muscle cells by mechanisms involving the recruitment of glucose transporters to the cell surface and modulation of their expression. Neuregulins may also participate in the adaptations in glucose transport that take place in the muscle fiber after denervation.

Posterior corneal curvature changes after myopic laser in situ keratomileusis

OBJECTIVE

To assess the posterior corneal power and asphericity changes after myopic laser in situ keratomileusis (LASIK) and to correlate these changes with the amount of correction and the residual stromal bed thickness.

DESIGN

Prospective nonrandomized (self-controlled) comparative study.

PARTICIPANTS

Fifty-seven eyes of 14 women and 15 men, mean age at the time of surgery 33 +/- 9 (range, 19-53) years with a spherical equivalent (SEQ) of -1.00 to -15.50 (mean, -5.07 +/- 2.81) diopters (DI).

INTERVENTION

All procedures were performed with the Keratom II Coherent-Schwind excimer laser and and the Moria Model One microkeratome (150-microm head). Subjective refractometry, Orbscan slit scanning corneal topography analysis and pachymetry were performed before and 3 months after LASIK for myopia (n=35, -1.00 to -15.50 D, mean -4.75 +/- -3.07 D) or myopic astigmatism (n=22, sphere 0.00 to -9.75 D, mean -4.75 +/- 2.36 D; cylinder -0.75 to -3.50 D, mean -1.68 +/- 0.86 D). Intended ablation depth ranged from 12 to 108 (mean, 48 +/- 22) microm. Topographic raw data were decomposed into a set of Zernike polynomials as published in detail previously, and parameters potentially indicative for detection of a "mild keratectasia" were derived.

MAIN OUTCOME MEASURES

Posterior central corneal power and asphericity before and after LASIK were compared, and changes of these variables were correlated with the SEQ change (deltaSEQ)and the residual corneal bed thickness RBT).

RESULTS

The mean RBT after LASIK was 280 +/- 42 microm. Overall, change of posterior power (-6.28 +/- 0.22 D/ -6.39 +/- 0.23 D, P=0.02) was statistically significant and change of asphericity (0.98 +/-0.07/1.14 +/- -.20, P<0.0001) was highly significant. In eyes with RBT < or =250 microm, the average change of posterior central power (-0.20 +/- 0.10 D vs. -0.08 +/- 0.18 D) was significantly greater than in eyes with RBT >250 microm (P=0.003). The change of posterior corneal power correlated significantly with deltaSEQ (P=0.004) and the RBT (P=0.002).

CONCLUSIONS

Increased negative keratometric diopters and oblate asphericity of the posterior corneal curvature suggest that mild "keratectesia" of the cornea may be common early after LASIK. Further stuudies with longer follow-up are required to clarify whether this biomechanical deformation is progressive and whether a residual bed thickness of >250 microm can completely prevent it.

Fragmentation of carbohydrate anomeric alkoxy radicals. synthesis of polyhydroxy piperidines and pyrrolidines related to carbohydrates

Imino sugars of the piperidine and pyrrolidine types can be specifically obtained when protected 5-amino-5-deoxyfuranopentoses, 5-amino-5-deoxyfuranohexoses, 6-amino-6-deoxyfuranohexoses, and 6-amino-6-deoxypyranohexoses undergo a tandem alkoxy radical beta-fragmentation-intramolecular cyclization reaction. The reaction is promoted by the system: iodosylbenzene-iodine under mild conditions. The tert-butoxycarbonyl, benzyloxycarbonyl, and diphenylphosphinoyl radicals have been studied as amino-protecting groups. Using this methodology, polyhydroxylated pyrrolidines of the D-erythrofuranoses 34 and 35, D-threofuranose 36, L-xylofuranose 42, and D-arabinofuranose 43 series and polyhydroxylated piperidines of the D-arabinopyranose type 37 and 38 were obtained.

Multicenter retrospective study of response to interferon in chronic hepatitis B

AIM

The only agent known to have a lasting beneficial effect in chronic hepatitis B is interferon alpha, which achieves long-term remission in 25-40% of the patients. The goals of treatment are to induce clearance of HBV DNA from serum, to return serum aminotransferases to normal, and to improve histological findings in the liver. The most important factors predictive of response to treatment are high serum aminotranferases levels, low serum HBV DNA concentrations, and active histologic changes on liver biopsy. The aim of this study was to assess the response to interferon alpha in patients with chronic hepatitis B and to analyze the factors predictive of response.

METHODS

We conducted a multicenter retrospective study to investigate the effect of interferon treatment in 132 patients with chronic hepatitis B in overall terms and based on HBeAg, and factors predictive of response.

RESULTS

A overall sustained response was noted in 59 of 132 interferon-treated patients (45%) and 61 patients were nonresponders (46%). 12 patients relapsed (9%). None of the patients had negative HBsAg. No difference was observed in the response rate between the two treatment groups (HBeAg-positive and HBeAg-negative patients). Overall, high initial levels of serum AST and ALT predicted a good response. Age and liver biopsy findings were factors predictive of response in HBeAg-positive and HBeAg-negative patients respectively. Sex, epidemiological factors, treatment and type of virus did not correlate with the response to interferon.

CONCLUSIONS

A sustained response to interferon alpha was observed in 45% of the patients with chronic hepatitis B. HBeAg seroconversion was found in up to 50% of HBeAg-positive patients. None of the patients had negative HBsAg. Overall, the response rate was higher in patients with high pretreatment serum aminotransferase levels. Age was the predictive factor in HBeAg-positive patients, and histological features were predictive in the HBeAg-negative group. However, further studies in a larger patient population are necessary to obtain well-substantiated conclusions.

Variations in the survival probabilities of the PVC-protected red mangrove propagules: testing the encased replanting technique

The EcoEléctrica Mangrove Planting Project, a five-year voluntary effort, has the purpose of testing a recently developed mangrove planting technique at the EcoEléctrica site in Peñuelas, Puerto Rico. The goal of the project is to provide empirical validation to promote or improve the technique to be used in recovering mangrove ecosystems in Puerto Rico and United States. The research presented herein analyzed the information collected on the first two years of the project. The proportions of remaining casings and seeds per study zone were compared using the chi-square distribution. Zone 1 had the least pipes lost while Zone 4 had the most (p < 0.05). Forty-three percent of the seeds in Zone 1 remained in the casing, while 26% remained in Zone 2 (p = 0.03). Median growth rates of seeds per study zone showed that Zone 1 had the highest median growth rates. Survival analysis described the survival experience of the seeds, and differences in survival probabilities were compared with the log-rank test. Zone 1 seeds had a better survival experience compared to Zones 2, 3 and 4 (p < 0.0001). Survival probabilities for being free of spots were over 60% during the whole study period. No significant differences were observed in the survival experience with the use-or-no use of casing extensions (p = 0.40), and the use-or-no use of nursed seeds (p = 0.26). Differences in survival probabilities might be attributed to variations in wave energy, depth or substrate conditions. This hypothesis will be evaluated in the second phase of the study.

[A comparative study of indinavir versus ritonavir for assessing the development of opportunistic diseases in adult AIDS patients]

This observational study compared the probability of developing the first opportunistic infection among AIDS adult patients attending the "Programa SIDA de San Juan" who received either indinavir plus zidovudine and lamivudine (n = 45) or ritonavir plus zidovudine and lamivudine (n = 16) between August 1, 1996 and July 31, 1997. No significant differences were observed with respect to appearance of an opportunistic infection, increase in CD4 levels and decrease in viral load between both groups during the study period. However, an increased probability of being free of opportunistic infection after 10 months was observed for the indinavir group (p > 0.05). In addition, the probability of changing or interrupting prescribed therapy was 2 times higher for patients under ritonavir (p < 0.05). These results suggest the need to confirm these findings in a larger group of patients in a controlled clinical trial and to assess the short-term and long-term effects of both therapies among Puerto Rican AIDS patients.

[Methodological aspects of biostatistics and epidemiology in a clinical trial]

Various methodological issues in biostatistics and epidemiology which are relevant for the development of a clinical trial are discussed. A brief set of definitions regarding clinical trials and methods for the assignment of treatments is presented. In addition, methods to reduce the possibility of bias that may be introduced into a clinical trial are summarized. The different elements that must be included in the informed consent form are defined. General considerations for data analysis and for sample size required to obtain an adequate statistical power are illustrated. Finally, critical questions that can be used for the review of the literature on clinical trials are suggested.

Serum protein binding of itraconazole and fluconazole in patients with diabetes mellitus

The protein binding of itraconazole and fluconazole in the serum of patients with insulin-dependent (IDDM) and non-insulin-dependent (NIDDM) diabetes mellitus was investigated in vitro. The unbound percentage of itraconazole in patients with IDDM and NIDDM was significantly higher than that in healthy volunteers. In contrast, there were no significant differences in fluconazole protein binding. A negative correlation was established between itraconazole protein binding and albumin concentration, and a positive correlation with free fatty acid concentration. The existence of a larger percentage of unbound itraconazole in diabetes patients could imply a change in drug disposition and an alteration in the effect of the drug. This should be taken into consideration in long duration treatment, especially in view of the non-linear kinetics of itraconazole.

The significance of lipoproteins in serum binding variations of propofol

The protein binding of propofol was investigated in vitro in isolated lipoprotein fractions (very low-density lipoprotein [VLDL], low-density lipoprotein [LDL], and high-density lipoprotein [HDL]) and in serum samples from the following subjects: healthy normolipemic volunteers (n = 16), hyperlipidemic subjects diagnosed with familiar polygenic hypercholesterolemia (n = 26) showing high levels of cholesterol, and elderly subjects (n = 15). Protein binding was determined by using ultrafiltration, and the concentration of unbound propofol was measured by using liquid chromatography. Levels of total cholesterol, triglycerides, VLDL cholesterol, LDL cholesterol, HDL cholesterol, albumin, and alpha1-acid glycoprotein were also measured. Propofol was extensively bound to the three lipoprotein fractions (88%+/-2% to VLDL, 93%+/-1% to LDL, and 91%+/-4% to HDL). The percentage of unbound propofol was significantly decreased (P < 0.0001) in hyperlipidemic (0.88%+/-0.20%) individuals whose levels of cholesterol and triglycerides were increased versus healthy subjects (1.26%+/-0.22%), whereas no significant difference was found in the elderly group (1.12%+/-0.23%). A positive relationship was found between serum protein binding of propofol and lipid levels. Multiple regression analysis, including all subjects, showed that changes in the levels of total cholesterol and triglycerides explained approximately 62% of the variability in the serum protein binding of propofol. These results stress the importance of triglycerides and cholesterol in the serum protein binding of propofol. We therefore suggest that these variations in lipid levels, and consequently in protein binding, may influence anesthetic practice with propofol.

IMPLICATIONS

We investigated the effect of serum lipids in the protein binding of propofol. We found that propofol binds extensively to all lipoprotein fractions. Propofol binding showed a significant relationship with the serum levels of cholesterol and triglycerides.

Serum protein binding of lerisetron, a novel specific 5HT3 antagonist, in patients with cancer

The aim of this study was, (1) to characterize the serum protein binding of lerisetron, a new 5-hydroxytryptamine (5-HT3) receptor antagonist under investigation as an antiemetic agent, and (2) to measure the percentage of unbound lerisetron in cancer patients. The binding parameters were determined in human serum albumin (HSA), alpha1-acid glycoprotein (AAG) and in pooled serum from six healthy volunteers. Concentrations of lerisetron ranging from 50 ng/ml to 2 microg/ml were used. The serum protein binding of 14C-lerisetron (2 microg/ml) was determined by ultrafiltration in three groups of individuals. Group I comprised healthy subjects (n = 11), group II comprised cancer patients undergoing radiotherapy (n = 9), and group III comprised cancer patients receiving chemotherapy (n = 18). The unbound concentration of lerisetron was measured in all samples by liquid scintillation counting. Concentrations of both AAG and HSA were also measured in all serum samples. The drug was extensively bound in pooled serum, involving a nonsaturated process. In HSA, lerisetron was also highly bound (4.04+/-0.8% unbound) and the protein binding was essentially unchanged within the studied concentration range of lerisetron. The extent of binding to AAG was high but significantly lower than in serum and in HSA and was also independent of lerisetron concentration. The unbound lerisetron was significantly decreased in group II cancer patients when compared with group I subjects (2.38+/-0.64% vs 3.70+/-0.70%; P < 0.001). No significant changes in lerisetron binding were observed in group III patients. HSA was diminished in both groups of patients and AAG was only significantly increased in group II. Unbound lerisetron was correlated with AAG in group II and with HSA in group III.

Differential expression of the p27Kip1 mRNA in IFN-sensitive and resistant cell lines

IFNs arrest the growth of a small cell lung cancer (SCLC) cell line NCI-H82 in the G1 phase but not the growth of the derived cell line NCI-H82R. Progression through the G1 phase is controlled by positive and negative regulatory genes. Oncoviral genes can override this control. In this study, we compared the effects of human IFN alpha 2b on the mRNA levels of the Cdk inhibitor p27Kip1 in NCI-H82, NCI-H82R and HPV 16 E7-transfected NCI-H82 cell lines. Induction of the 2-5 Oligoadenylate synthetase (2-5 OAS) gene was used as a marker of IFN-dependent signal transduction The expression of p27Kip1 mRNA increased at 48 and 72 hr after IFN alpha 2b addition in sensitive cells. In contrast, p27Kip1 mRNA had only slight variations in both the resistant and E7-transfected cells. Interestingly, the E7-transfected NCI-H82 cells became resistant to the IFN alpha 2b anti-proliferative effect. Our results suggest that p27Kip1 could be a key mediator of the IFN alpha 2b-induced growth arrest and that HPV 16 E7 might affect p27Kip1 inducibility, originating IFN alpha 2b-resistant cells.

Serum protein binding of propofol in critically ill patients

BACKGROUND

Disease-induced modifications in the level of serum proteins may change the degree of binding of drugs highly bound to serum proteins.

METHODS

The serum protein binding of propofol, an intravenous anaesthetic agent was studied in vitro in samples of serum from healthy volunteers (n=28) and from critically ill patients (n=17). The free fraction was obtained by the ultrafiltration technique and was measured by high-performance liquid chromatography. Concentrations of serum albumin, alpha1-acid-glycoprotein and free fatty acids were also measured in all samples.

RESULTS

The percentage of free propofol was significantly increased (P<0.001) in critically ill patients (1.31 (1.06-2.25)%) vs control subjects (1.07 (0.49-1.47)%). Albumin levels were significantly decreased (P<0.001) in patients (16.3 (8.8-24.6) g x l(-1) vs 45.8 (31.4-55.5) g x l[-1]), while levels of alpha1-acid-glycoprotein were increased (P<0.001) (1.9 (0.9-2.8) g x l(-1) vs 0.9 (0.5-1.4) g x l[-1]), as were levels of free fatty acids (0.68 (0.50-1.14) mmol x l(-1) vs 0.37 (0.11-1.05) mmol x l(-1); P<0.05 ). No correlation was found between levels of alpha1-acid-glycoprotein or free fatty acids and the bound/free ratio of propofol. However, a linear relationship was found between levels of albumin and the bound/free ratio (r2=0.25; P<0.001).

CONCLUSION

In conclusion, in these critically ill patients, an increase in the percentage of free propofol occurs. The significance of this observation remains uncertain, but may be validated in future studies. However, the observation supports the common idea that potent drugs should be given with great care in critically ill patients.

Pharmacokinetic-pharmacodynamic modeling of mivacurium in rats

The pharmacokinetic (PK) and pharmacodynamic (PD) characteristics of the neuromuscular blocking agent mivacurium were evaluated separately in two groups of rats receiving 0.6 mg kg-1 of mivacurium in a 2.5-min intravenous continuous (iv) infusion. The PK parameters for mivacurium were determined in the first group. A two-compartment model describes the kinetics of mivacurium in plasma. The estimates of the apparent volume of distribution at steady-state and plasma clearance [mean(SE)] were 650 (123) mL kg-1 and 9.9 (0.75) mL min-1 kg-1, respectively. In the second group, the evoked tibialis anterior muscle tension was monitored. The PK parameters derived from the first group were used to compute mivacurium plasma concentrations (C) at the times the PD measurements were recorded in the second group. The concentration-neuromuscular effect [% depression of initial twitch tension (E)] relationship was analyzed by two approaches. (1) The relationship of estimated effect site concentrations versus E; a sigmoidal Emax model described the effect compartment concentrations versus E relationship. The estimate [mean(SE)] of Cess50 (steady-state plasma concentration eliciting half of maximum E) was 0.65 (0.01) microgram mL-1. The value [mean-(SE)] of Keo (rate constant of equilibration between plasma and effect site) was estimated at 0.32 (0.03) min-1. (2) The relationship of descending limb C versus E; a sigmoidal Emax model described such relationship. The estimate [mean(SE)] of C50 (post-infusion C eliciting half of maximum E) was 0.57(0.03) microgram mL-1. The PD properties of mivacurium were also evaluated in another two groups of animals receiving either 5- or 10-min continuous iv infusion; PK and PD parameters obtained from the 2.5-min infusion experiments were used to predict the time course of E in the groups receiving 0.6 mg kg-1 of mivacurium in 5- and 10-min infusions; simulations using the estimated parameters adequately describe the time course of E in those groups. The effect of mivacurium on the mean arterial blood pressure (MAP) was also investigated; a 10% nonsignificant decrease (p > 0.05) in MAP was found in all groups.

Pneumocystis carinii pneumonia versus wasting syndrome among AIDS cases in Puerto Rico: a survival analysis

OBJECTIVE

To compare mortality of wasting syndrome (WS) versus Pneumocystis carinii pneumonia (PCP) in AIDS patients reported in Puerto Rico after controlling for gender, age, and CD4 levels.

METHODS

AIDS patients for which a diagnosis of WS (n = 1,180) or PCP (n = 765), who were reported to the AIDS Surveillance System of Puerto Rico between 1989 and 1992, were used to analyze the mortality risk among these diagnoses using a Cox's proportional hazard regression model.

RESULTS

Cox model showed that WS patients had a 14% to 33% reduction in mortality risk compared with PCP patients after adjusting for gender and age (95% confidence level). Mortality risks for males were 18% (95% CI: 1%, 39%) higher than females risk after adjusting for AIDS defining condition and age. It was shown that a decrease in 100 CD4 cells increased the mortality by 37% (95% CI: 16%, 62%) after adjusting for AIDS defining conditions, gender, and age.

Serum protein binding of propofol in patients with renal failure or hepatic cirrhosis

BACKGROUND

Serum protein binding is a limiting factor in the access of drugs to the central nervous system. Disease-induced modifications of the degree of binding may influence the effect of anesthetic drugs.

METHODS

The protein binding of propofol, an intravenous anaesthetic agent which is highly bound to serum albumin, has been investigated in serum samples from healthy volunteers, from patients with chronic renal failure not undergoing hemodialysis, from patients with chronic renal failure included in a regular hemodialysis program, and from patients with hepatic cirrhosis. Protein binding was determined by the ultrafiltration technique using an Amicon Micropartition System, MPS-1.

RESULTS

The percentage of unbound propofol (mean(SD)) in healthy volunteers (n = 16) was 0.98 (0.48) % showing a high interindividual variability. Chronic renal failure did not significantly modify serum protein binding of propofol. In the chronic renal failure group not undergoing regular hemodialysis (n = 9), unbound propofol was 0.92 (0.34) %. In addition, patients in periodic dialysis did not show changes in propofol binding either compared before (1.11 (0.33) %; n = 13) or after hemodialysis (0.87 (0.38) %; n = 12). A slight decrease in albumin concentration was found in all renal patients (P < 0.05) in comparison to healthy volunteers. Creatinine and urea concentrations were higher in these patients (P < 0.01) but in the postdialysis group, the differences in urea levels were not significant when compared with those of volunteers. No changes in the degree of propofol binding were observed in patients with hepatic cirrhosis (0.97 (0.30) %; n = 14) when compared with the group of healthy volunteers. Significant differences were observed in albumin (P < 0.01) and bilirubin (P < 0.05) concentrations. Considering all subjects, the degree of binding did not correlate with biomedical data.

CONCLUSION

Due to the absence of significant changes in the protein binding it is unlikely that there will be an exaggerated pharmacological response in patients with renal and hepatic disease following the administration of a standard propofol dose, although due to interpatient variability careful titration can be recommended.

Resistance to atracurium in rats with experimental inflammation: role of protein binding

The influence of altered protein binding on the neuromuscular effect of atracurium has been studied in rats with experimental inflammation induced by subcutaneous injection of turpentine oil. Doses of atracurium ranging from 0.45 to 1.5 mg.kg-1 were administered to control (n = 30) and to experimental inflammation induced rats (n = 30). Neuromuscular transmission was monitored by recording the twitch tension of the tibialis-anterior muscle elicited by stimulation of the sciatic nerve. Three effect parameters were recorded: (i) intensity of the effect, measured as percentage depression of baseline twitch tension, (ii) duration of drug action (min) and (iii) recovery time (min). The dose-intensity of the effect relationship was modelled using a sigmoid Emax model. The ED50 (effective dose eliciting 50% of the maximum effect) was significantly increased (P < 0.01) in the inflammation group as compared to the control group (0.94 vs. 0.68 mg.kg-1). This change was reflected in a shift of the dose-response curve to the right in the pretreated rats. For equipotent doses ED95 (defined as the effective dose eliciting 95% of maximum effect), no differences were found in recovery time and duration of action between the two groups of rats. Mucoproteins levels (index of alpha 1-acid glycoprotein (AAG) and protein binding were significantly increased in rats with experimental inflammation as compared to control rats. Based on these results, altered serum protein binding of atracurium appears to be responsible, at least in part, for the resistance to atracurium.

Altered methadone analgesia due to changes in plasma protein binding: role of the route of administration

1. The effect of experimental inflammation on methadone analgesia was evaluated in rats, by the tail-flick test, after single intravenous (0.35 mg/kg) and subcutaneous (3 mg/kg) doses. 2. After i.v. administration a significant decrease (P < 0.05) in the area under the methadone time-response curve was seen in rats with experimental inflammation, when compared with control. However, no differences in the analgesic response to methadone were detected between control rats and rats with inflammation when the drug was administered by s.c. injection. 3. Plasma mucoprotein levels were significantly increased (P < 0.001) and methadone free fraction was significantly decreased in rats with inflammation (P < 0.05). In addition, after i.v. methadone a decrease in brain uptake in rats with inflammation was detected. A significant correlation between brain uptake index and plasma free fraction was also observed. 4. These results suggest that a decreased immediate response to i.v. methadone may occur in circumstances in which there is an increase in alpha 1 acid glycoprotein, but that this is not likely to be observed when the absorption is not instantaneous.

Changes in the analgesic effects of mianserin associated with altered plasma protein binding in experimental cancer

In a group of mice bearing experimentally induced tumors, the protein binding of mianserin in vitro was measured and compared with a control group. The analgesic effect and the brain uptake of drug was also compared with a control group after an intraperitoneal dose of mianserin. The unbound percentage of mianserin in the plasma of mice with experimental cancer decreased with respect to control animals (5.20 +/- 0.12 vs 6.06 +/- 0.26; p<0.05) and alpha1-acid glycoprotein (AAG) levels, measured as plasma mucoprotein concentrations, were significantly increased (p<0.05). The brain/plasma drug concentration ratio of mianserin decreased in mice with experimental cancer when compared with control mice (1.11 +/- 0.03 vs 1.42 +/- 0.10; p<0.02). In both groups of mice, the mianserin analgesic effect was evaluated by the hot plate test after intraperitoneal drug administration. When the analgesia response-dose curve (0-60 mg/kg) was studied, a significant decrease in the response in mice with experimental cancer versus control mice was observed. These results suggest that resistance to the mianserin analgesic response may occur in animals with cancer disease. This resistance may be associated, in part, with an altered plasma protein binding, but other mechanisms could be involved.

Differential effect of cancer on the serum protein binding to mianserin and imipramine

Protein binding of mianserin and imipramine in vitro was determined in sera from 10 patients with cancer and from 28 drug-free normal subjects. alpha 1-acid glycoprotein (AAG) concentrations ranged from 0.91 +/- 0.04 g/l in control subjects to 2.17 +/- 0.18 g/l in cancer patients. Albumin concentrations ranged from 55.80 +/- 1.68 g/l in control subjects to 39.71 +/- 4.40 g/l, respectively. Serum samples containing concentrations of 100 ng/ml for mianserin and 500 ng/ml for imipramine were ultrafiltered and the free concentration were measured with scintillation spectrophotometer. The mean free percentage of mianserin was significantly less in patients with cancer (8.70 +/- 0.29% in patients vs 14.30 +/- 0.50% in control subjects P < 0.001). A multiple regression analysis revealed a significant contribution of plasma AAG (r2 = 0.56, P < 0.01), but not of albumin to the overall variability in mianserin binding. No correlation was observed between protein binding of imipramine and AAG concentrations in serum of cancer patients. No significant changes were observed for protein binding of imipramine in cancer patients as compared with control subjects. Our results suggest that for antidepressant (AD) drugs, of which the binding depends on AAG, variability in protein binding could be expected in cancer patients. Thus, in cancer therapy, changes in analgesic doses could be necessary with this kind of antidepressant drug.