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Biomedical subjects

D A Kidwell

Publications and source records attributed to D A Kidwell.

At least 19 recordsLinked to original sources
PubMed2003

Comparison of daily urine, sweat, and skin swabs among cocaine users.

This study (1) compares urine, skin swabs, and PharmChek sweat patches for monitoring drug use; (2) measures possible environmental contamination in recent cocaine (COC) users; and (3) evaluates various immunoassays (IA) for screening COC in diverse matrices. Unique aspects include daily urine monitoring of 10 participants for 4 weeks, multiple monitoring methods, analysis for all specimens by IA and gas chromatography (GC)/mass spectrometry (MS), and the potential for continued illicit drug use by participants. Urine served as the "gold standard" specimen for determining drug use. Only cocaine and related substances were detected. Trace amounts of drugs were found on the skin (<50 ng per swab) of urine-negative participants' hands or forehead. In contrast, larger quantities of COC were found on the skin of individuals with BE-positive urines or individuals living with drug users (up to 20 microg per swab). Patch COC amounts among the three regular users (250-9000, 0-240, 160-22,000 ng per patch) exceeded BE (50-950, none, 30-2200 ng per patch). Pre-swabs, valuable for interpreting the source or time frame of positive patch results, contained substantial COC (38-1160, 0-152, 34-762 ng per swab) prior to patch application; therefore, patch results may represent current use, prior use, contamination, or a combination. In three individuals with no indication of cocaine use, false positives (defined as sweat patch positive when urine specimens were <300ng BE/ml) occurred at a 7% rate. Proposed cut-off concentrations of 75 ng cocaine per patch and 300 ng BE/ml urine curtail the incidence of false positives in this limited population. Three immunoassays were compared to screen specimens for cocaine: a modified, manual Microgenics CEDIA; a Cozart ELISA; and an OraSure ELISA. CEDIA's limit of detection (LOD) was 81ng/ml, compared with LODs of 4 ng/ml for the Cozart ELISA and 1.5 ng/ml for the OraSure ELISA. Cozart correlated with OraSure results for COC concentrations <2000 ng per swab (n=117), r(2)=0.79.

Adult↗
PubMed2001

Susceptibility of PharmChek drugs of abuse patch to environmental contamination.

The key component of the PharmChek sweat patch, the membrane, has been tested for the passage of externally applied materials. Drugs in the uncharged state rapidly penetrated the membrane but charged species were greatly slowed. In basic media, detectable concentrations of cocaine, methamphetamine, and heroin were observed at the earliest collection time (ca. 30 s), after drugs were placed on the outside of the membrane. Drug concentrations increased over the 2 h time course, when amounts detected (1710 ng cocaine, 1060 ng methamphetamine, 550 ng heroin per pad at 2 h) represented 5-17% of the drug deposited on the surface of the sweat patch. Drugs externally applied to human skin were shown to bind readily. Drugs deposited on the skin of drug-free volunteers several days prior to application of the sweat patch were not completely removed by normal hygiene or the cleaning procedures recommended before application of the sweat patch. Even 6 days of normal hygiene did not remove all drugs from externally contaminated skin and positive sweat patches resulted. A mechanism for passage of drugs through the sweat patch membrane, a mechanism for retention of drugs on skin, and a redesign of the sweat patch and modification of its use to reduce external contamination are proposed. Appropriate care should be taken in the interpretation of positive results from a sweat patch test until more research is conducted.

Bandages↗
PubMed2000

Evidence for bias in hair testing and procedures to correct bias.

A number of in vitro experiments show that different hair samples incorporate differing amounts of drugs under identical conditions. Incorporation of cocaine and morphine tends to be correlated with race, in that the hair of African American females incorporates higher concentrations of cocaine than does the hair of Caucasian males or females. Extrapolation of these data into populations has been fraught with difficulties because the dosages of drugs and their use patterns are unknown. Cosmetic treatments and hygiene alter drug binding, which must be considered in comparing populations because cosmetic treatments are often group dependent. Four reasons are proposed that account for the uptake and retention of drugs by hair and that may differ among groups: (1) permeability and other characteristics of the hair due to genetic influences, (2) cosmetic hair treatments and hair care habits (which may be culturally influenced), (3) drug removal during personal hygiene, and (4) manner and route of drug administration which can affect passive exposure to residual drugs in the environment. The data supporting bias in hair testing are reviewed and methods are proposed that use either the uptake of dyes or the incorporation of drug homologs to reduce bias.

Bias↗
PubMed2000

The incorporation of dyes into hair as a model for drug binding.

The binding of charged substances from external aqueous media to hair has been investigated through the use of fluorescence microscopy. Eleven hair samples, reflecting various ethnic groups and cosmetic treatments, were tested. Rhodamine 6G, a cationic dye representative of drugs such as cocaine and opiates, showed incorporation throughout the hair of all samples except one. In contrast, fluorescein, an anionic dye representative of drugs such as THC carboxylic acid, was not readily incorporated. The incorporation of rhodamine 6G was faster for chemically 'straightened' and bleached African-American female hair than for untreated hair. Incorporation of rhodamine 6G followed a pH dependence, but an ionic strength dependence could not be established. These studies support three postulates: (1) electrostatic interactions explain the preferential binding of cationic drugs of abuse to hair; (2) the hair matrix, or the non-helical portion of hair, is accessible to external solutions and thus subject to contamination; and (3) cosmetic treatments may alter the helical portion of hair thereby increasing its accessibility to external contamination.

Black or African American↗
PubMed1998

Testing for drugs of abuse in saliva and sweat.

The detection of marijuana, cocaine, opiates, amphetamines, benzodiazepines, barbiturates, PCP, alcohol and nicotine in saliva and sweat is reviewed, with emphasis on forensic applications. The short window of detection and lower levels of drugs present compared to levels found in urine limits the applications of sweat and saliva screening for drug use determination. However, these matrices may be applicable for use in driving while intoxicated and surveying populations for illicit drug use. Although not an illicit drug, the detection of ethanol is reviewed because of its importance in driving under the influence. Only with alcohol may saliva be used to estimate blood levels and the degree of impairment because of the problems with oral contamination and drug concentrations varying depending upon how the saliva is obtained. The detection of nicotine and cotinine (from smoking tobacco) is also covered because of its use in life insurance screening and surveying for passive exposure.

Biological Transport↗
PubMed1997

Cocaine detection in a university population by hair analysis and skin swab testing.

The ability to detect cocaine use/exposure by either hair or sweat analysis was compared in a random population of adults at a major US university. Sweat was obtained by wiping the forehead with a cosmetic puff containing isopropanol. Using cut-off levels for sweat of 2.2 ng cocaine/wipe and of hair of 0.05 ng cocaine/mg hair, sweat detected two times more cocaine use/exposure than did hair. Sweat analysis detected a use rate of 12% compared to a 6% rate by hair analysis, both greater than the 2% that would be expected in this population. The high rate of detection was surprising and suggests that use of, if not exposure to, cocaine is underreported. Controlled experiments showed that cocaine could remain on the skin for about 3 days after external exposure. At the current state of knowledge, sweat appears to measure both use and exposure. Nevertheless, sweat testing could be used in several scenarios (such as roadside driving while intoxicated) where the case of collection and testing of sweat could outweigh the passive exposure considerations. Cocaine concentrations in skin swabs > 15 ng/swab would appear to indicate recent use/exposure.

Adolescent↗
PubMed1996

Cocaine in hair, saliva, skin swabs, and urine of cocaine users' children.

The concentrations of cocaine and benzoylecgonine (BE) in the hair, saliva, skin secretions, and urine samples of cocaine-using mothers, their children, and other adults living in the same environment were compared. Subjects were screened from urban cocaine dependence treatment patients. Drug using adults had mean hair concentrations of 2.4 ng cocaine/mg hair (range = 0-12.2, sigma = 3.1, 15/16 positive) and 0.39 ng BE/mg hair (range = 0-1.9, sigma = 0.62), compared with children's mean hair concentrations of 2.4 ng cocaine/mg of hair (range = 0-14.4, sigma = 3.8, 22/24 positive) and 0.74 ng benzoylecgonine/mg hair (range = 0-5.4 sigma = 1.3). None of the children's urine specimens (0/22) were positive above 300 ng BE/ml. In contrast, 3/16 adult urine specimens were positive, even though they were enrolled in drug treatment. Saliva had detectable levels of BE for only one child (1/17) and one adult (1/17). Forehead swabs contained measurable quantities of cocaine for most children (19/26) and adults (15/17) and BE for children (7/26) and adults (7/17). Unlike urine results, overall hair cocaine concentrations for adults paralleled those of children and a clear cut-off concentration could not be established to differentiate these two groups.

Adolescent↗
PubMed1995

Decontamination procedures for drugs of abuse in hair: are they sufficient?

This paper reviews the methods for decontaminating hair exposed to external solutions of drugs of abuse. Exposure of hair to cocaine at 1 microgram/ml for 5 min is sufficient to contaminate hair, yet decontamination is a very slow process. Using externally contaminated hair, a number of decontamination procedures were attempted, and none removed all the contamination. The percentage of external contamination removed depended on the hair type, with thick black hair being the most resistant to decontamination. Hair treated by dying incorporated externally applied drugs differently, depending on the hair type. Thick black hair became more absorbent whereas thin brown hair became less absorbent. Kinetic wash criteria are evaluated for their ability/inability to determine if hair has been contaminated from external sources. A theoretical framework for the incorporation and removal of drugs from hair is discussed, and the hypothesis that inaccessible domains exist in hair which trap drugs is critically examined. The results presented in this paper strongly suggest that much more information on the decontamination of hair and the differentiation of exogenously and endogenously incorporated drugs is needed before hair analysis can be employed in most forensic applications. We propose that the radioactive tracer methods discussed herein are well suited for evaluating any new decontamination or extraction technique.

Decontamination↗
PubMed1993

External contamination of hair by cocaine: an issue in forensic interpretation.

This paper explores the variables by which hair samples may become contaminated with cocaine and thereby generate false positives during analysis of hair samples. A novel method for following the incorporation and removal of cocaine from hair was developed. This method allowed a large number of specimens to be analysed under a variety of conditions with high precision. The quantity of cocaine was carefully followed in each step of a published procedure. Regardless of washing technique, a substantial amount of cocaine could still be found in the final hair digest. Very few of our externally contaminated samples could be identified as externally contaminated by previously published criteria and washing procedures. Attempts to further decontaminate this hair were without success. Our data strongly suggest that external contamination of hair by drugs of abuse may make the interpretation of forensic results problematical.

Cocaine↗
PubMed1993

Analysis of phencyclidine and cocaine in human hair by tandem mass spectrometry.

A confirmation procedure for the analysis of cocaine, benzoylecgonine, ecgonine, and phencyclidine (PCP) in human hair using tandem mass spectrometry has been developed. This procedure requires no solvent extraction and thus can examine the metabolites of drugs such as cocaine. Hairs from six cocaine users were examined and the amount of cocaine and its ratio to the metabolites was not correlated to the reported use pattern. Only PCP was detected in the hair from a PCP user, no metabolites were found. In passive exposure experiments, hair was found to tightly absorb PCP from aqueous solutions, which mimics the incorporation of PCP by the body. These results indicate that drugs may be absorbed onto the hair of nonusers and become tightly bound.

Cocaine↗
PubMed1992

Discussion: caveats in testing for drugs of abuse.

Four mass screening techniques for drugs of abuse (TLC, RIA, EMIT, and FPI) have been described. For small-scale screening, TLC is the most cost-effective. Although it cannot achieve the sensitivity of the other three immunologically based techniques, TLC is sufficient for many purposes. All screening techniques are subject to interferences that can generate false-negatives or false-positives. These results must be taken into account in analysis of the research data. In applying technology in new areas of research, one has to be aware of the basis and limits of that technology. Testing of drugs of abuse in urine is a well-known technology in which most of the problems have been discovered. This technology is less proven for other media, such as hair, saliva, or meconium, leaving potential pitfalls for the unwary researcher.

Humans↗
PubMed1991

Chromogenic substrates for horseradish peroxidase.

Two new detection systems for horseradish peroxidase (HRP) have been developed for the staining of membranes used in immunoassays. These systems use dimethyl or diethyl analogues of p-phenylenediamine with 4-chloro-1-naphthol to generate a blue product or 3-methyl-2-benzothiazolinone hydrazone with 4-chloro-1-naphthol to generate a red product. These reagents offer increased sensitivity and lower background staining than currently available chromogenic detection substrates. In addition, the incorporation of these substrates increases the sensitivity of HRP labels to be comparable to that of alkaline phosphatase with the 5-bromo-4-chloro-3-indolyl phosphate + nitro blue tetrazolium substrate.

Alkaline Phosphatase↗
PubMed1991

Isomeric amphetamines--a problem for urinalysis?

Alkyl amphetamine isomers (amphetamine, 1-phenyl-2-butylamine (PBA), methamphetamine, N-methyl-PBA, N,N-dimethylamphetamine, N-ethylamphetamine, N-ethyl-PBA and N,N-diethylamphetamine) were purchased or synthesized and tested by immunoassay and GC/MS for their detectability in urine. Some cross reactivity was observed with PBA, N-methyl-PBA N-ethylamphetamine, and N-ethyl-PBA when analyzed using a series of commercial amphetamine and methamphetamine immunoassays. Chromatographic co-elution problems were observed for the underivatized isomeric group N,N-dimethylamphetamine, N-ethylamphetamine, and N-methyl-PBA under GC/MS conditions used; and their GC/MS spectra were quite similar. Of the potential derivatives, pentafluoropropionyl (PFP) anhydride and heptafluorobutyryl (HFB) anhydride provided adequate separation and easily distinguishable spectra using the electron-impact GC/MS conditions specified.

Amphetamines↗
PubMed1989

Superabsorbent polymers--media for the enzymatic detection of ethyl alcohol in urine.

Superabsorbent polymers are shown to be an excellent medium for the detection of enzymes used in enzyme assays. They offer increased sensitivity of 2-10 times over conventional blotter medium. Their usefulness is demonstrated with a quick, inexpensive, visual test for alcohol in urine with sensitivity approaching 0.001% (w/v). Alcohol levels in 500 random urine samples were determined and the levels ranged from 0.06 to less than 0.001%, with the majority of positives being near 0.005%.

Absorption↗
PubMed1985

Enhanced detection of drugs in complex mixtures by derivatization/secondary ion mass spectrometry.

Derivatization/secondary ion (SI) mass spectrometry is a sensitive surface analysis technique. It can detect ppm levels of selected compounds in complex mixtures, as can tandem mass spectrometry. However, unlike tandem mass spectrometry it uses simpler instrumentation, since chemistry is used to select the compound of interest instead of a mass spectrometer. The application of derivatization/SI mass spectrometry is discussed regarding the analysis of drugs in aqueous media, tablets or human urine.

Chemical Phenomena↗