Effects of kava (Kava-kava, 'Awa, Yaqona, Piper methysticum) on c-DNA-expressed cytochrome P450 enzymes and human cryopreserved hepatocytes.

The effects of the herbal product kava (Kava kava, 'Awa, Yaqona, Piper methysticum) on human P450 isoforms were studied in vitro using both cDNA-expressed human enzymes and cryopreserved human hepatocytes. Increasing concentrations of an ethanolic extract of dried kava root and three purified kava lactones (methysticin, desmethoxyyangonin, and yangonin) were tested for their ability to inhibit the catalytic activity of a panel of P450 isoforms (1A2, 2A6, 2C9, C2C19, 2D6, 2E1, and 3A4) present as c-DNA expressed-enzymes and in previously cryopreserved human hepatocytes. In addition, the test compounds' effect on hepatocyte viability was evaluated by measuring cellular ATP content. In both models, the kava extract and the three kava lactones were found to be potent inhibitors of CYPs 1A2, 2C9, 2C19, 2E1, and 3A4 with IC50 values of approximately 10 microM. The test compounds were also moderately cytotoxic to human hepatocytes (EC50 values of approximately 50 microM). Methysticin was the most potent enzyme inhibitor as well as the most cytotoxic, followed by (in order of potency:) the kava root extract, desmethoxyyangonin, and yangonin. Our results suggest that the drug interaction and hepatotoxic potential of kava should be further investigated.

Effects of herbal components on cDNA-expressed cytochrome P450 enzyme catalytic activity.

We evaluated the effects of 25 purified components of commonly used herbal products on the catalytic activity of cDNA-expressed cytochrome P450 isoforms in in vitro experiments. Increasing concentrations of the compounds were incubated with a panel of recombinant human CYP isoforms (CYP1A2, CYP2C9, CYP2C19, CYP2D6 and CYP3A4) and their effects on the conversion of specific surrogate substrates measured fluorometrically in a 96-well plate format. For each test substance, the IC50 (the concentration required to inhibit metabolism of surrogate substrates by 50%) was estimated and compared with IC50's for the positive control inhibitory drugs furafylline, sulfaphenazole, tranylcypromine, quinidine, and ketoconazole. Constituents of Ginkgo biloba (ginkgolic acids I and II), kava (desmethoxyyangonin, dihydromethysticin, and methysticin), garlic (allicin), evening primrose oil (cis-linoleic acid), and St. John's wort (hyperforin and quercetin) significantly inhibited one or more of the cDNA human P450 isoforms at concentrations of less than 10 uM. Some of the test compounds (components of Ginkgo biloba, kava, and St. John's wort) were more potent inhibitors of the isoforms 1A2, 2C19, and 2C19 than the positive controls used in each assay (furafylline, sulfaphenazole, and tranylcypromine, respectively), which are known to produce clinically significant drug interactions. The enzyme most sensitive to the inhibitory of effects of these compounds was CYP2C19, while the isoform least effected was CYP2D6. These data suggest that herbal products containing evening primrose oil, Ginkgo biloba, kava, and St. John's Wort could potentially inhibit the metabolism of co-administered medications whose primary route of elimination is via cytochrome P450.

Effects of intrinsic fluorescence and quenching on fluorescence-based screening of natural products.

To evaluate the effects of intrinsic (natural) fluorescence and quenching as confounding variables in fluorescence-based enzyme inhibition assays of natural products, we measured the fluorescence and quenching properties of 25 components of popular herbal products. The analyses were performed under conditions typically employed in drug-drug interaction studies that use c-DNA-derived P450 isoforms and surrogate fluorogenic substrates. Four of the 25 compounds tested (isorhamnetin, quercetin, vitexin, and yangonin) fluoresced or quenched sufficiently to interfere with these assays. Intrinsic fluorescence had a greater effect on these assays than quenching and for one compound, yangonin, was sufficient to mask inhibition and potentially produce a false negative result. Quenching had less of an effect on these assays, but was significant enough for one compound, quercetin, to mimic "weak" inhibition. Therefore, because intrinsic fluorescence or quenching could render some natural products unsuitable for testing in certain fluorometric assays, it would be prudent to include an evaluation of these properties in experimental protocols.

Quantitative determination of ginsenosides by high-performance liquid chromatography-tandem mass spectrometry.

An HPLC-MS/MS method was developed for the quantitative determination of ginsenosides, which are the marker compounds for herbal products containing Panax ginseng (Korean or Chinese ginseng) and P. quinquefolius (American ginseng). Samples were extracted with BondElut C18 HF extraction columns and the concentrations of seven major ginsenosides (Rb1, Rb2, Rc, Rd, Re, Rf, and Rg1) were determined by reversed-phase HPLC-MS/MS employing a quadrupole-ion trap mass spectrometer. Both positive and negative electrospray ionisation techniques were evaluated. Positive ionisation spectra of these compounds gave strong sodium adduct molecular and sodium adduct dimer ions. Negative ionisation yielded the molecular ion primarily and was, therefore, used for analysis: quantitative determination was based on the most abundant product ions for each ginsenoside. The method was used to extract and analyse commercial samples of P. ginseng and P. quinquefolius.

Variability in commercial ginseng products: an analysis of 25 preparations.

BACKGROUND: Because dietary supplements are not subject to the same regulations that pharmaceuticals are, there is concern among medical professionals that these products may lack purity or potency. OBJECTIVE: To determine the variability in a range of ginseng herbal products available in the United States, we identified and measured the concentration of marker compounds by using HPLC and liquid chromatography-tandem mass spectrometry. DESIGN: Twenty-five commercial ginseng preparations from the genera Panax or Eleutherococcus were obtained from a local health food store and analyzed for 7 ginsenosides (marker compounds for Panax species, which include Asian and American ginseng) and 2 eleutherosides (marker compounds for Eleutherococcus senticosus, also known as Siberian ginseng). RESULTS: All plant products were correctly identified by botanical plant species (ie, Panax species or E. senticosus); however, concentrations of marker compounds differed significantly from labeled amounts. There was also significant product-to-product variability: concentrations of ginsenosides varied by 15- and 36-fold in capsules and liquids, respectively, and concentrations of eleutherosides varied by 43- and 200-fold in capsules and liquids, respectively. Although a systematic search for adulterants was not conducted, review of the HPLC and liquid chromatography-tandem mass spectrometry data suggest that no substances other than ginsenosides or eleutherosides were extracted from the plant material. CONCLUSION: Our data suggest that US ginseng products are correctly labeled as to plant genus; however, variability in concentrations of marker compounds suggests that standardization may be necessary for quality assurance and that characterization of herbal products should be considered in the design and evaluation of studies on herbal products.

Shosaiko-to and other Kampo (Japanese herbal) medicines: a review of their immunomodulatory activities.

The use of alternative medicine, including consumption of herbal products and dietary supplements, has been increasing substantially both in the United States and in Western Europe. One area that is garnering increased attention is the use of Oriental Medicine including Kampo, or Japanese herbal medicine. Herein, we review representative examples of research available on the most common use of Kampo medicinals, namely to improve the immune response. We also provide an extensive background on the history of Kampo. There are more than 210 different Kampo formulae used in Japan and most uses of Kampo are to modulate the immune response, i.e. to improve immunity. We have extracted data on seven common Kampo medicinals, and the data are reviewed with respect to in vitro and in vivo activities for both humans and experimental animals; the ingredients as well as the problems with classification of these materials are presented. Research suggests that Kampo herbals are biologically active and may have therapeutic potential. While it is believed that Kampo medicines have few side effects, there is a paucity of data on their toxicity as well as a relative lack of knowledge of the bioactive constituents and potential drug interactions of these agents.

Effects of ginseng components on c-DNA-expressed cytochrome P450 enzyme catalytic activity.

Because little is known about the interactions between herbal products and standard medications, the effects of seven ginsenosides and two eleutherosides (active components of the ginseng root) on the catalytic activity of c-DNA expressed cytochrome P450 isoforms were studied in in vitro experiments. Increasing concentrations of ginsenosides Rb1, Rb2, Rc, Rd, Re, Rf, and Rg1 and eleutherosides B and E were incubated with a panel of recombinant human CYP isoforms (CYP1A2, CYP2C9, CYP2C19, CYP2D6 and CYP3A4) and their effects on the conversion of specific surrogate substrates measured fluorometrically in a 96-well plate format. For each test substance, the IC50 (the concentration required to inhibit the metabolism of the surrogate substrates by 50%) was estimated and this value compared with that obtained for positive control inhibitory drugs furafylline, sulfaphenazole, tryanylcypromine, quinidine, and ketoconizole. Of the components tested, three ginsenosides (Rd, Rc, and Rf) modified the activity of the recombinant enzymes. Ginsenoside Rd produced weak inhibitory activity against the surrogate substrates for CYP3A4 and CYP2D6 and even weaker inhibitory activity against the surrogate substrates for CYP2C19 and CYP2C9. The IC50 values of 58 and 74 uM for the two substrates for CYP3A4 are orders of magnitude higher than that for the potent inhibitor ketoconazole used as a positive control. Ginsenoside Rc produced an increase in the activity of CYP2C9 (70% at 200 uM) and ginsenoside Rf produced an increase in the activity of CYP3A4 (54% at 200 uM). The biological significance of this is unclear at this time. Enzyme "activation", the process by which direct addition of one compound to an enzyme enhances the rate of reaction of the substrate, has been observed in a number of cases with P450 enzymes; however, a matrix effect caused by the test compound fluorescing at the same wavelength as the metabolite of the marker substrate cannot be ruled out. In summary, these studies suggest that the ginsenosides and eleutherosides tested are not likely to inhibit the metabolism of coadministered medications in which the primary route of elimination is via cytochrome P450; the potential of ginsenosides to enhance the catalysis of certain substrates requires further investigation.

Incorporation of isotopically labeled cocaine into human hair: race as a factor.

In order to evaluate race as a possible factor affecting the incorporation of drugs into human hair, 2 mg/kg deuterium-labeled cocaine (cocaine-d5) was administered intranasally to nine male non-Caucasian volunteers under controlled laboratory conditions. Sequential blood samples were collected for up to three days, and scalp hair samples were collected at 24 and 72 h after dosing and at monthly intervals for up to 12 months. The samples were then analyzed by gas chromatography-mass spectrometry for cocaine-d5 and benzoylegonine-d5 (BZE-d5). The amounts of cocaine-d5 found in the hair of these non-Caucasian subjects were compared with the amounts of cocaine-d5 found in the hair of Caucasian subjects who received the same cocaine dose under identical conditions as part of a study we reported previously. The non-Caucasians in the present study had approximately 2.7 times more cocaine-d5 in their hair than the Caucasian subjects in the earlier study. In five of the non-Caucasian subjects, cocaine-d5 could be detected in hair within 24 h after dosing. Curiously, we were unable to detect any cocaine-d5 in one of the non-Caucasian subject's hair at any time after dosing even though cocaine-d5 was in plasma at the expected levels. The results from these studies suggest there may be a racial bias in the incorporation of cocaine into human hair; however, the data are not conclusive because of the relatively small sample size.

The effect of chronic cocaine exposure during pregnancy on maternal and infant outcomes in the rhesus monkey.

To explore the effects of gestational cocaine exposure in a nonhuman primate model, pregnant rhesus monkeys were treated from about 1 month of gestation until term with either 0 (N = 3), 0.3 (N = 3), 1.0 (N = 3), or escalating doses up to 8.5 (N = 3) mg/kg (IM), three times per day, 5 consecutive days per week. Despite these differences in cocaine exposure, the experimental groups did not differ significantly with respect to maternal outcome, as measured by body weight gain during pregnancy and length of pregnancy. A clear dose-response relationship was observed between the cumulative dose of cocaine administered during gestation and the levels of both cocaine and its major metabolite, benzoylecgonine, in samples of infant hair taken at birth. However, the experimental groups did not differ significantly with respect to infant outcome, as measured at birth by body weight, overall length, crown-to-rump length, rump-to-heel length, biparietal diameter, and crown circumference. Furthermore, the experimental groups did not differ significantly with respect to the integrity of a variety of infant reflexes tested at birth. It was concluded that, in a rhesus monkey model, chronic cocaine exposure during pregnancy had no significant effect on maternal and infant outcomes as assessed in this investigation.

Incorporation of isotopically labeled cocaine and metabolites into human hair: 1. dose-response relationships.

Deuterium-labeled cocaine (cocaine-d5) was administered intravenously and/or intranasally in doses of 0.6-4.2 mg/kg to 25 human volunteers under laboratory clinical conditions. Sequential blood samples were collected for up to 3 days, and hair samples were collected for up to 10 months. Samples were analyzed by gas chromatography-mass spectrometry (GC-MS) for cocaine-d5 and its major metabolite, benzoylecgonine-d5 (BZE-d5). The parent drug, cocaine-d5, was the predominant analyte in hair, whereas BZE-d5 was the major analyte in blood, especially at later time periods. The amount of cocaine-d5 incorporated into hair ranged from 0.1 to 5 ng/mg hair, whereas the amount of BZE-d5 was approximately one-sixth of that concentration. The threshold dose for detection was estimated to be 25-35 mg of drug administered intravenously. A single dose could be detected for 2-6 months. Subjects receiving the same dose differed (from two to 12 times as much depending upon how it was measured) in the amount of cocaine-d5 incorporated into their hair. Non-Caucasians, in particular, incorporated more cocaine-d5 in hair than did Caucasians. Also, segmental analysis of the samples revealed considerable intersubject variability in the time drug first appeared in hair and the rate at which the drug moved along the hair shaft with time. These interindividual differences could not be explained by differences in plasma pharmacokinetics. Considered together, these results suggest that cocaine incorporation into hair may occur by way of multiple mechanisms--by way of sweat and sebum, for example--and at various times during the hair growth cycle. Thus, hair analysis using GC-MS appears to be a very sensitive method for detecting cocaine ingestion. However, within the range of doses used in the present study, hair does not provide a particularly accurate record of either the amount, time, or duration of drug use.

Metabolism of 4-methylaminorex ("EU4EA") in the rat.

Metabolism studies were conducted on 4-methylaminorex (4,5-dihydro-4-methyl-5-phenyl-2-oxazolamine [4-MAX]), a potent central nervous system stimulant that has emerged as a drug of abuse under the name "EU4EA", "EU4Euh", and "Ice". Tritiated norephedrine was cyclized with cyanogen bromide to form 3H-4-MAX, which was administered to rats at a dose of 10 mg/kg orally and intravenously. Radioactivity was excreted almost entirely in urine (40% of the dose was excreted by 24 h), primarily as the parent drug (60% of the total excretions were as the parent compound). Three metabolites were identified by high-performance liquid chromatography-tandem mass spectrometry with thermospray ionization: norephedrine, 5-phenyl-4-methyl-2-oxazolidinone, and 2-amino-5-(p-hydroxyphenyl)-4-methyl-2-oxazoline. Stability studies showed that 4-MAX in aqueous solution degraded very slightly to norephedrine upon standing. There was no evidence for glucuronide or sulfate conjugation. These results suggest that the metabolic fate of 4-MAX is similar to that of the amphetamines in that it is eliminated primarily unchanged but undergoes some slight oxidative deamination and aromatic hydroxylation. Hydrolytic degradation back to the synthetic precursor can also occur. There was no evidence for the hydrolysis of the oxazolamine ring to form a urea that has been reported for the demethylated congener aminorex. This suggests that 4-methyl substitution of the oxazoline ring may inhibit metabolism similar to the alpha-methyl substitution of beta-phenylethylamines.

Mechanisms of drug incorporation into hair.

The model generally proposed to explain the incorporation of drugs into hair is one in which drugs enter hair only by passive diffusion from the blood stream into the growing cells at the base of the hair follicle. However, this model may be over-simplified. More recent experimental findings suggest that drugs may enter hair from multiple sites, via multiple mechanisms, and at various times during the hair growth cycle. A more complex model is proposed in which drugs and metabolites are incorporated into hair during formation of the hair shaft (via diffusion from blood to the actively growing follicle), after formation (via secretions of the apocrine and sebaceous glands), and after hair has emerged from the skin (from the external environment). Further, drugs can be transferred to hair from multiple body compartments or pools located in tissues surrounding the hair follicle. These mechanisms could also be drug-specific. A more precise understanding of the mechanisms involved in the incorporation of drugs into hair is critical for forensic scientists in order to interpret the results of hair analysis properly.

Cocaine and metabolite concentrations in the hair of South American coca chewers.

Hair samples obtained from South American Indians who were identified as daily chewers of coca leaves were analyzed by a sensitive gas chromatography/mass spectrometry (GC/MS) method for cocaine, benzoylecognine (BE), and ecognine methyl ester (EME). The mean cocaine concentration in the hair of these five subjects was 15.2 ng/mg hair +/- 11.0 (range = 1.0-28.9 ng/mg), mean BE concentration was 2.8 +/- 1.6 ng/mg hair (range = 0.3-4.4 ng/mg hair), and mean EME concentration was 1.6 +/- 1.7 (range = 0.0-4.4 ng/mg hair). The finding that cocaine was present at approximately 5 times higher concentration than BE and approximately 12 times higher than EME is surprising in light of the much longer plasma half lives of these metabolites. Washing the hair before analysis with 1% dodecyl sulfate, methanol, and distilled water reduced the concentration of cocaine in the hair but also reduced the concentrations of the metabolites. These data suggest that factors other than the drug concentration in blood may be important in determining the amount of drug incorporated into hair.

Simultaneous quantitation of cocaine and its major metabolites in human hair by gas chromatography/chemical ionization mass spectrometry.

A sensitive method for the simultaneous analysis of cocaine, benzoylecgonine (BE), and ecgonine methyl ester (EME) in human hair by gas chromatography/chemical ionization mass spectroscopy (GC/CIMS) is described. Hair samples are cut into 1-cm sections, washed with 1% sodium dodecylsulfate, rinsed with deionized water and methanol, and then digested overnight in a solution containing Tris buffer, sodium dodecylsulfate, Proteinase K, and dithiothreitol. Digested hair samples are extracted with Bond Elut Certify solid-phase extraction columns, derivatized with N-methyl-N-(tert-butyldimethylsilyl)-trifluoroacetamide (MTBSTFA), and analyzed by GC/CIMS using isobutane as reagent gas. This method is quantitative, does not cause degradation of cocaine, and requires as little as 5 mg of hair. Analysis is performed on a Finnigan ITS-40 ion trap mass spectrometer interfaced with a Varian 3400 gas chromatograph equipped with a Model 1075 split/splitless injector and a J&W DB-5 capillary column. Full scan spectra are used for identification of cocaine and its metabolites. Quantitation is based on peak area ratios of the MH+ ions, as follows: 304 for cocaine, 404 for BE-TBDMS, 314 for EME-TBDMS, and 340 for the internal standard, difluorococaine. This method can be used to quantitate cocaine at concentrations of 0.1 to 100 ng/mg hair. The coefficients of variation (%CV) at a drug concentration of 1 ng/mg hair are 10.3, 16.3, and 27.7% for cocaine, BE, and EME, respectively.

Fentanyl-related deaths: demographics, circumstances, and toxicology of 112 cases.

Since 1979, the potent narcotic analgesic fentanyl and its analogs have been synthesized in clandestine laboratories and sold as heroin substitutes. At least 112 overdose deaths have been associated with their use. In this study, toxicology data, autopsy findings, and coroners' investigative reports were reviewed in order to construct a profile of the typical fentanyl overdose victim and to identify any factors that might heighten the risk of death from fentanyl use. The "typical" fentanyl overdose victim was 32.5 +/- 6.7 years of age (range, 19 to 57 years), male (78%, compared with 22% female), and Caucasian (50%, compared with 29% Hispanic, 20% Black, and 0.9% Asian). With the exception of his or her age, the typical fentanyl overdose victim is quite similar to the typical heroin user. Nearly all the deaths (94%) occurred in California, yet within the state they were widely distributed throughout 17 counties and 44 cities. Pulmonary edema and congestion and needle puncture sites were consistent postmortem findings. No preexisting medical conditions were identified as possible risk factors. Although most of the fentanyl victims had a prior history of intravenous drug use, morphine or codeine were not commonly found, which suggests that the victims had little or no opiate tolerance. Ethanol was present in 38% of the cases and is thought to be a significant risk factor. Mean fentanyl concentrations in the body fluids were quite low: 3.0 +/- 3.1 ng/mL (0.3 +/- 0.31 micrograms/dL) in blood and 3.9 +/- 4.3 ng/mL (0.39 +/- 0.43 micrograms/dL) in urine, measured by radioimmunoassay. Although the potency of the analogs and the purity of street samples varies considerably, it is probably the general availability of the drug rather than the potency of a particular analog that determines the incidence of overdose deaths.

Rapid screening of fentanyl (China White) powder samples by solid-phase radioimmunoassay.

We report the use of a solid-phase radioimmunoassay (RIA) to rapidly screen powder samples for various illicit fentanyl analogs. A 10-mg sample is dissolved in water, serial dilutions are made over a range of 1:10 to 1:100,000, and then duplicate 50-microL aliquots are analyzed by RIA. This method was verified by analyzing 18 "China White" samples, first by RIA and then by gas chromatography/mass spectrometry (GC/MS) with the spectrometrist blind to the results of the RIA. Of the samples, 11 were positive by radioimmunoassay and all were confirmed by GC/MS and found to contain fentanyl, alpha-methylfentanyl, fluorofentanyl, cis- and trans-3-methylfentanyl, thienylfentanyl, or cis- and trans-3-methylthienylfentanyl. The seven samples that were negative by RIA contained a variety of substances typically found in street drug samples--caffeine, codeine, and heroin--but none of the fentanyls. Differences in fentanyl concentration between samples were quite large, up to 300-fold; however, the drug seems to be uniformly distributed within a single sample. Thus, accidental overdose is more likely to result from the large intersample variability in drug concentration rather than the "clumping" of fentanyl within a sample. This solid-phase RIA provides a simple, rapid, and reliable screening method for detecting fentanyl and its illicit analogs in powder samples.

Analyzing normetabolites of the fentanyls by gas chromatography/electron capture detection.

A selective and sensitive gas-liquid chromatographic (GC) method has been developed for analyzing the normetabolites of fentanyl and 3-methylfentanyl in urine. The method employs differential pH extraction of 1 mL samples, extractive acylation with pentafluoropropionic anhydride (PFPA), GC separation on a fused-silica capillary column (DB-1701), and detection by electron capture detector (ECD) or mass spectroscopy (MS). Limit of sensitivity for this method is 2 ng/mL for norfentanyl (NF) and nor-3-methylfentanyl (N-3-MF) using a 1-mL urine sample and a 2-microL injection from a final volume of 20 microL. Within-run precision, expressed as the coefficient of variation (CV), was 14% and 5% for 4 ng/mL and 16 ng/mL of NF and 9% and 4% for the same concentrations of N-3-MF. Between-run precision was 30% and 12% for NF and 11% and 10% for N-3-MF, at 4 ng/mL and 16 ng/mL, respectively. Metabolites are stable in urine for at least one month at room temperature (25 degrees C) or -20 degrees C. PFP-derivatives of the metabolites were confirmed by high-resolution MS in the electron-impact mode. Three characteristic ions for each metabolite were identified-m/z 392 (molecular ion), m/z 336 (loss of propionyl), and m/z 244 (loss of propionanilide) for N-3-MF-PFP and m/z 378 (molecular ion), m/z 322 (loss of propionyl), and m/z 230 (loss of propionanilide) for NF-PFP, suitable for use in GC/MS with selected ion monitoring as a complimentary confirming technique. This method was validated by analyzing urine samples from individuals suspected of using fentanyl or 3-methylfentanyl.(ABSTRACT TRUNCATED AT 250 WORDS)

Designer drugs: past history and future prospects.

Historically, drugs of abuse have come from two sources: plant products and diverted pharmaceuticals. Today, new, totally synthetic drugs produced by clandestine laboratories have become an increasingly important source of abused substances. Of particular concern are the fentanyls, a family of very potent narcotic analgesics, which first appeared on the streets in California in 1979 under the name "China White". At least 10 different analogs have been identified to date and are thought to be responsible for over 100 overdose deaths. The fentanyls are not used by any particular ethic or age group, but rather by the general heroin using population. Their use, however, does seem to be restricted to suburban, rather than urban areas, and almost exclusively to the state of California. The most potent analogs, the 3-methyl- and beta-hydroxy-fentanyls, may be up to 1000 times as potent as heroin, but are not chemically related to the opiates and therefore not detected by conventional narcotic screening tests. However, using a sensitive radioimmunoassay highly specific for the fentanyls they can be measured at the very low concentrations observed in body fluids, generally less than 10 ng/mL. It is likely that, as efforts to restrict the importation of natural products and prevent diversion of pharmaceuticals become more effective, the fentanyls and other synthetics will become increasingly important drugs of abuse.

Tocainide suppression of immune-complex-mediated dermal inflammation: comparison with prostaglandin E1.

Local anesthetic agents have been shown to alter a variety of polymorphonuclear leukocyte (PMN) functions and may be useful as anti-inflammatory agents. We compared the anti-inflammatory effects of therapeutic doses of the recently released local anesthetic-antiarrythmic drug tocainide to pharmacologic doses of prostaglandin E1 (PGE1) on immune-complex-mediated dermal inflammation in female Sprague-Dawley rats. Intense dermal inflammation was produced using a classic reverse passive Arthus reaction, and the inhibition of PMN accumulation in the subdermis was quantitated in biopsy samples taken 2.5 hr after the reaction was initiated and the drug was given. Using a light microscope with a counting grid, biopsy sections were randomly sampled in a blinded fashion and an inflammation index equal to the ratio of PMNs to fibroblasts was determined for each animal. The mean inflammation index in 10 animals given 25 mg of tocainide (mean serum level = 14.6 micrograms/ml) was 9.3 +/- 1.2 (+/- SEM), which was significantly less than the index of 17.7 +/- 2.5 in 10 control animals (P less than 0.025). Similarly, the five animals that received either 500 or 250 micrograms of PGE1 had a significantly reduced index, with the effect of 250 micrograms PGE1 comparable to the effect of the tocainide. These findings suggest that therapeutic levels of tocainide reduce the accumulation of PMNs in immune-complex-mediated dermal inflammation; thus, local anesthetic agents may be useful in the treatment of certain inflammatory disorders.