G. John Digregorio

Diazepam concentrations in parotid saliva, mixed saliva, and plasma

The concentration of diazepam in the plasma and saliva of 9 normal human subjects receiving a single oral dose of diazepam (10 mg) over an 8‐hr period was determined by gas‐liquid chromatography/electron capture analysis. In addition, the binding of diazepam to plasma protein in these subjects was determined using equilibrium dialysis at specific time intervals corresponding to periods of plasma and saliva collection. A linear relationship was found between diazepam concentration in plasma and that in both mixed and parotid saliva, over plasma concentrations ranging from 196 ± 16.4 to 74.8 ± 10.3 ng/ml. The elimination constants (−Ke) were 0.13, 0.17, 0.18 for diazepam disappearance from plasma, parotid saliva, and mixed saliva, respectively. The mean parotid concentration ratio was 0.035 and the mixed saliva/plasma diazepam concentration ratio was 0.029. These were not affected by variations in plasma diazepam levels. The percentage of the plasma diazepam concentration in both parotid saliva (3.5%) and mixed saliva (2.9%) was of the same order as the fraction of diazepam found to be free from plasma protein in these subjects (2.0% to 3.5%). The results indicate that there is no significant difference between parotid saliva and mixed saliva concentrations over a period of 8 hr after a single oral dose of diazepam. The results strongly suggest that the appearance of diazepam in saliva may provide an alternate, non invasive method of determining plasma diazepam levels.

The presence of cocaine and benzoylecgonine in rat cerebrospinal fluid after the intravenous administration of cocaine.

Cocaine hydrochloride, in doses of 0.5, 1.0, 2.0 and 4.0 mg/kg, iv, was administered to male Sprague-Dawley rats. Cerebrospinal fluid (CSF) was collected from the cisterna magna over a 20 min period and blood samples were obtained at 20 min after cocaine administration. In addition, blood samples for the 1 mg/kg dose of cocaine were collected at 2, 10, 20 and 30 min following drug injection. Gas chromatography/mass spectrometry was used for the analysis of cocaine and its metabolites in plasma and CSF. The disappearance of cocaine (1 mg/kg) from the plasma exhibited first order kinetics with a half-life of 18.11 +/- 3.22 min. Cocaine and benzoylecgonine were found in CSF and the concentrations of cocaine and benzoylecgonine increased in CSF as the doses of cocaine were increased. CSF flow rates were not altered by the iv administration of cocaine or benzoylecgonine. The CSF-to-plasma ratios for cocaine were quite similar to each other over the dosage range of cocaine that was administered; however, the CSF-to-plasma ratios for benzoylecgonine decreased as the concentrations of benzoylecgonine increased in plasma and CSF. When benzoylecgonine (2 mg/kg, iv) was given, the compound was detected in CSF indicating that benzoylecgonine can enter into the central nervous system from the peripheral blood. This investigation shows that cocaine and benzoylecgonine can be assayed in CSF and that the plasma levels of these compounds correlate with their concentrations in CSF.

Lead and δ-aminolevulinic acid concentrations in human parotid saliva

Abstract Quantitative values of lead and δ-aminolevulinic acid in normal human parotid saliva were determined and were found to be 3.1 (±0.5) and 10.2 (±0.6) μg/100 ml, respectively. The relationship of salivary lead concentration to blood lead concentration was examined. For the experimental population studied, parotid saliva was estimated to contain approximately 13% of the blood lead concentration. No significant difference was found between parotid saliva and plasma δ-aminolevulinic acid concentrations.

Correlations of parotid saliva and blood ethanol concentrations

Abstract This paper is devoted to the detection and quantitation of blood and parotid saliva ethanol in both human subjects and rats. The human ethanol saliva-plasma ratio has been determined to be 1.04 utilizing a collection technique which is non-invasive and easily performed. The rat ethanol saliva-plasma ratio has been found to be 1.21 with a direct cannulation technique of the parotid duct. Differences between the human and rat ratios have been attributed to the method of salivary gland stimulation. The human parotid gland was stimulated by a reflex action of an organe-flavored lozenge, whereas the rat parotid gland was stimulated by a direct infusion of pilocarpine. The results indicate that the rat parotid secretion of ethanol is very similar to the human secretions, and the rat could possibly be utilized as an animal model for future alcohol salivary studies.

Pharmacokinetics of theophylline in rats with biliary stasis.

catecholamines from adrenergic neural endings in the Borda, E., Agostini, M. C., Sterin-Borda, L., Gimeno, M., rat uterus, an organ with a high sensitivity for noradreGimeno, A. (1981) naline (Borda et al 1981). Brimblecombe, R. W., Duncan, W. A. M., Owen, D. A. This indirect action should be taken into account A., Parsons, M. E. (1976) Fred. Proc. Fed. Am. SOC. when using these drugs as a tool in the pharmacological ExP. Bid. 35: 1931-1934 characterization of the receptors involved in the Goyal, R. K., Verma, s. c. (1981) Agents Actions 11: response to histamine in the isolated uterus of the rat. 312-317 J . Pharmacol. 69: 55-62

Excretion of Barbiturates into Induced Parotid Saliva of the Rat

Anesthetic doses of barbiturates administered to rats were excreted into the parotid saliva. Plasma-saliva concentration ratios were compared to several physicochemical parameters-lipid-water partition coefficient (L/W), degree of ionization, and plasma protein binding-of which L/W appears to correlate best with the excretion of barbiturates into parotid saliva.

A small animal model utilizing salivary drug excretion for pharmacokinetic determinations

Abstract The use of small laboratory animals for pharmacologic research is well established. The need for more and varied information demands extensive data from these small animal experiments. Pharmacokinetic investigations, in particular, require frequent sampling of various biological fluids for drug level information. Such multiple/sequential sample collection has heretofore been possible only in larger animals and humans. The method presented here allows sequential collection of whole blood, parotid saliva, and cardiovascular information in a small animal model. Furthermore, this study demonstrates the usefulness of such a model for investigating drug interactions resulting from competition at plasma protein binding sites. Male Wistar rats received pentobarbital anesthesia and underwent a surgical procedure to facilitate stimulation and collection of parotid salivary secretions. Saliva and simultaneously collected whole blood samples were analyzed for pentobarbital content in the presence and absence of phenylbutazone, a highly competitive protein binding agent. In addition, arterial blood pressure was monitored to determine the effects of such drug displacement interactions on the cardiovascular system. Results indicate that pentobarbital levels in plasma decrease, while levels in saliva increase, following intravenous infusion of phenylbutazone. This effect was attributed to a displacement of pentobarbital from plasma protein binding sites by the more highly bound phenylbutazone. This shift in drug concentration correlated well with depressions in arterial blood pressure noted after phenylbutazone administration. It is apparent from these findings that phenylbutazone causes a relative increase in the free (nonprotein bound) levels of pentobarbital in plasma that are immediately available for transport to peripheral tissues, including the salivary glands and the central nervous system, where it depresses cardiovascular tone. We believe that this model provides a reliable mechanism for the study of a variety of problems that require multiple and/or sequential sampling of biological fluids in small animals. Additionally, this method is particularly useful in investigations requiring cardiovascular data to supplement drug level information. Possible applications of our method include bioassay and bioavailability studies of cardiotonic drugs, pressor and depressor agents. Of special interest is the ability of this method to elucidate mechanisms of drug interactions in vivo as demonstrated in our experiment.

In vitro study of antispasmodic effects of dicyclomine hydrochloride on vesicourethral smooth muscle of guinea pig and rabbit

Dicyclomine inhibition of acetylcholine-induced and barium chloride-induced isotonic contractions of the smooth muscle from three segments of the lower urinary tract (bladder body, bladder base, and proximal urethra) of the guinea pig and the rabbit was studied in vitro. In the guinea pig dicyclomine caused competitive inhibition of acetylcholine-induced contraction of the bladder body (1 x 10(-7) M to 1 x 10(-5) M) and the bladder base (1 x 10(-6) M, 1 X 10(-5) M) and was less potent than atropine and propantheline. In the rabbit significant blockade of acetylcholine-induced contractions occurred at dicyclomine concentrations of 5 x 10(-6) M to 3 x 10(-5) M in the bladder body and at 1 x 10(-5) M and 3 x 10(-5) M in the bladder base. In both species dicyclomine inhibitory effects were most marked in the bladder body, moderate in the bladder base, and minimal in the proximal urethra. Dicyclomine failed to cause inhibition of the barium chloride-induced contractions in the guinea pig vesicourethral smooth muscle. In rabbits, however, significant antagonism P less than 0.01) of barium chloride-induced muscle contraction was observed with dicyclomine at concentration 1 x 10(-5) M in both bladder body and the bladder base. The clinical implication of such properties of dicyclomine are discussed.

Radioimmunoassay of amphetamines in rat parotid saliva

Amphetamines, a commonly abused class of drugs, have been detected in various biological specimens, in particular, urine and blood. However, little information is available concerning the detection of these drugs in saliva. This investigation, utilizing the rat salivary secretions, has been attempted to establish the ability of amphetamines to be secreted in saliva and to determine the feasibility of using radioimmunoassay (RIA) for drug detection in saliva. The results of this investigation showed that (1) d-amphetamine and methamphetamine decreased salivary flow, (2) after d-amphetamine RIA tests were demonstrated in both saliva and plasma for a period of fifty minutes, and (3) positive RIA reactions were obtained by the following metamphetamine metabolites: amphetamine, 4-hydroxynorephedrine and 4-hydroxyamphetamine. Methamphetamine and 4-hydroxy-N-methylamphetamine were found to be non-reactive in the radioimmunoassay procedure. The results indicate that saliva could be radioimmunoassayed for the detection of amphetamine or amphetamine derivatives after the administration of either d-amphetamine and methamphetamine.

Quantitation and comparison of phenobarbital levels in the plasma, saliva, and cerebrospinal fluid of the rat, and the demonstration of an alteration of drug passage by ethanol.

In this study, the ability and extent of three biological fluids--plasma, saliva, and cerebrospinal fluid--to compartmentalize intravenously administered phenobarbital was examined and correlated. The three fluid compartments show markedly different levels of phenobarbital, though this probably does not reflect qualitative differences in the barriers that separate them, but rather in the nature of the compartments themselves. In addition to the quantitation and correlation of drug levels in the various compartments, intravenous administration of 400 mg/kg ethanol following the intravenous administration of 20 mg/kg phenobarbital was shown to alter the passage of phenobarbital into the different fluid compartments, causing a significant increase in the phenobarbital level of cerebrospinal fluid as compared to controls receiving no ethanol. Though the effect seen in the cerebrospinal fluid is significant, while the effect in saliva is not (though the trend was present), it is felt that the action of ethanol to alter drug passage is a non-specific effect on the vasculature. This finding of altered drug passage may help explain the observed synergistic interaction of ethanol and various sedative drugs.