Urine pH and phencyclidine excretion

Hair as a Biological Indicator of Drug Use, Drug Abuse or Chronic Exposure to Environmental Toxicants

In recent years hair has become a fundamental biological specimen, alternative to the usual samples blood and urine, for drug testing in the fields of forensic toxicology, clinical toxicology and clinical chemistry. Moreover, hair-testing is now extensively used in workplace testing, as well as, on legal cases, historical research etc. This article reviews methodological and practical issues related to the application of hair as a biological indicator of drug use/abuse or of chronic exposure to environmental toxicants. Hair structure and the mechanisms of drug incorporation into it are commented. The usual preparation and extraction methods as well as the analytical techniques of hair samples are presented and commented on. The outcomes of hair analysis have been reviewed for the following categories: drugs of abuse (opiates, cocaine and related, amphetamines, cannabinoids), benzodiazepines, prescribed drugs, pesticides and organic pollutants, doping agents and other drugs or substances. Finally, the specific purpose of the hair testing is discussed along with the interpretation of hair analysis results regarding the limitations of the applied procedures.

Interpretation of oral fluid tests for drugs of abuse

Oral fluid testing for drugs of abuse offers significant advantages over urine as a test matrix. Collection can be performed under direct observation with reduced risk of adulteration and substitution. Drugs generally appear in oral fluid by passive diffusion from blood, but also may be deposited in the oral cavity during oral, smoked, and intranasal administration. Drug metabolites also can be detected in oral fluid. Unlike urine testing, there may be a close correspondence between drug and metabolite concentrations in oral fluid and in blood. Interpretation of oral fluid results for drugs of abuse should be an iterative process whereby one considers the test results in the context of program requirements and a broad scientific knowledge of the many factors involved in determining test outcome. This review delineates many of the chemical and metabolic processes involved in the disposition of drugs and metabolites in oral fluid that are important to the appropriate interpretation of oral fluid tests. Chemical, metabolic, kinetic, and analytic parameters are summarized for selected drugs of abuse, and general guidelines are offered for understanding the significance of oral fluid tests.

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.

"Designer drugs"--a current perspective

Since the late 1970s, in an effort to quench the ever burgeoning appetite for pharmacological substances of abuse and to satiate their own need for profit, unscrupulous chemists have set up clandestine laboratories to produce and market new drugs for street sale. Using fairly common industrial chemicals, they have altered or modified preexisting controlled substances such as fentanyl, meperidine, mescaline, amphetamine, and phencyclidine, producing derivatives of these parent compounds that, up until 1986, were able to temporarily elude the guidelines of the Federal Controlled Substances Act due to their new and unique chemical structures. Unsuspecting users continue to use the drugs recreationally. This article will present a comprehensive review of these "Designer Drugs" looking at historical data, pharmacokinetics, treatment, abuse trends, and some of the more recent additions to the social pharmacopoeia.

Modification of phencyclidine intoxification and biodisposition by charcoal and other treatments

Studies were conducted to determine whether single or combination treatments of charcoal, paraffin, cholestyramine, and/or ammonium chloride (NH4Cl), would alter the rotarod-measured motor dysfunction induced by 10 to 90 mg/kg of phencyclidine (PCP). Additionally, the effect of NH4Cl/charcoal treatment of the biodisposition of 50 mg/kg PCP was evaluated in order to assess whether amelioration of behavioral effects could be correlated to alterations in brain levels, plasma levels, and/or the renal clearance of PCP and metabolites. NH4Cl/charcoal treatment proved more effective at reducing intoxication than either treatment singly, though effectiveness was reduced by larger doses of PCP. NH4Cl/charcoal treatment reduced intoxification by 40, 16, and 21% at PCP doses of 10, 25, and 50 mg/kg. However, the reduction in motor dysfunction observed at 25 and 50 mg/kg PCP was greater than the sum of the individual treatments. In contrast, the effect of combined NH4Cl and charcoal treatment on the biodisposition of 50 mg/kg PCP is not synergistic, but appears instead to be due simply to the additive effects of the individual treatments. Thus the amelioration of PCP intoxication cannot be fully explained by alterations in PCP biodisposition.

Effects of magnesium oxide on trichlormethiazide bioavailability

The effect of an antacid, magnesium oxide (MgO), on the bioavailability of a thiazide diuretic, trichlormethiazide, was studied in 10 healthy subjects who fasted overnight. A single oral dose of 4 mg of 1 alone or in combination with 0.5 g of MgO was given in a two-way Latin-square crossover design. Urine concentrations of 1 during the 24 h after each dose were determined by an HPLC method. There were no significant differences for drug alone versus drug with MgO in the mean percentage recovery (60 versus 62%) and the cumulative amount excreted unchanged in urine over 24 h (2408 versus 2463 micrograms). However, coadministration of MgO increased the mean excretion rate of 1 at 0.75 h and 1.5 h (p less than 0.05), the cumulative amount excreted unchanged in urine over 2 h (p less than 0.05), and the absorption rate constant (p less than 0.05). Therefore, the extent of bioavailability was not influenced by MgO, but the rate of absorption was enhanced. The solubility of 1 increased remarkably by changing from pH 1.2 to 8.0 (141 to 1365 micrograms/mL). The dissolution rate of 4 mg of 1 in 500 mL of medium was not affected by an increase in pH. However, a 1.5-fold increase of the dissolution rate in 20 mL of medium was observed by changing from pH 1.2 to 7.3.(ABSTRACT TRUNCATED AT 250 WORDS)