Salicylate Concentrations Research Articles

Fluoroquinolone resistance ofSerratia marcescens: sucrose, salicylate, temperature, and pH induction of phenotypic resistance

Serratia marcescens is a nosocomial agent with a natural resistance to a broad spectrum of antibiotics, making the treatment of its infections very challenging. This study examines the influence of salicylate, sucrose, temperature, and pH variability on membrane permeability and susceptibility of S. marcescens to norfloxacin (hydrophilic fluoroquinolone) and nalidixic acid (hydrophobic quinolone). Resistance of wild-type S. marcescens UOC-67 (ATCC 13880) to norfloxacin and nalidixic acid was assessed by minimal inhibitory concentration (MIC) assays after growth in the presence of various concentrations of sucrose and salicylate and different temperatures and pH values. Norfloxacin and nalidixic acid accumulation was determined in the absence and presence of (i) carbonyl cyanide m-chlorophenylhydrazone (CCCP), a proton-motive-force collapser, and (ii) Phe-Arg beta-naphthylamide (PAbetaN), an efflux pump inhibitor. Accumulation of norfloxacin decreased when S. marcescens was grown in high concentrations of salicylate (8 mmol/L) and sucrose (10% m/v), at high temperature (42 degrees C), and at pH 6, and it was restored in the presence of CCCP because of the collapse of proton-gradient-dependent efflux in S. marcescens. Although nalidixic acid accumulation was observed, it was not affected by salicylate, sucrose, pH, or temperature changes. In the absence of PAbetaN, and either in the presence or absence of CCCP, a plateau was reached in the nalidixic acid accumulation for all environmental conditions. With the addition of 20 mg/L PAbetaN nalidixic acid accumulation is restored for all environmental conditions, suggesting that this quinolone is recognized by a yet to be identified S. marcescens pump that does not use proton motive force as its energy source.

Percutaneous Penetration, Melanin Activation and Toxicity Evaluation of a Phytotherapic Formulation for Vitiligo Therapeutic

The aim of this work was to apply photoacoustic spectroscopy for the ex vivo determination of the penetration rate of a phytotherapic formulation for vitiligo therapeutic, with or without salicylic acid as the promoter agent. In addition, the compound toxicity and morphophysiology effects were evaluated for different concentrations of salicylic acid. The experiments were performed as a function of the period of time of treatment in a well-controlled group of rabbits. Toxic effects were not observed with any of the tested products. All formulations containing salicylic acid induced cutaneous reaction which was dose dependent. The histological analysis showed that the use of the medication was associated with an increased comedogenic effect in relation to the control group, regardless of salicylic acid concentration. Inflammatory reactions and acanthosis were observed only in the animals treated with formulations containing higher concentrations of salicylic acid, while none of these effects were detected with the use of the formulation containing 2.5% (wt/vol) of salicylic acid. Photoacoustic depth monitoring showed that both formulations, with or without salicylic acid, propagated through the skin up to the melanocytes region, suggesting that the transport of the active agent may occur through the epithelial structure without the need of using queratinolitic substances, which are known to induce side effects in the animals.

Bark salicylates and condensed tannins reduce vole browsing amongst cultivated dark-leaved willows (Salix myrsinifolia)

Vole feeding amongst herbal willows that have a high concentration of salicylates in their bark and leaves, and may therefore be cultivated for use as raw material for herbal medicine was tested in the field and in laboratory conditions. Eight clones of dark-leaved willow (Salix myrsinifolia Salisb.) were cultivated for two years with six different methods combining three fertilisation levels (none, low and high), black plastic mulch applied for suppressing weed competition and unmulched control. Samples for the laboratory feeding trial were taken from the unfertilised plants during willow winter dormancy and twigs were fed to 16 voles as a multi-choice experiment. The bark area removed was calculated from image analysis of the material left by the voles. The diameter and the bark thickness of the twigs were measured. Concentrations of salicin, salicortin, HCH-salicortin, picein, triandrin, triandrin derivative, gallocatechin, (+)-catechin, luteolin-7-glucoside, hyperin, total condensed tannins and total nitrogen were measured from the twigs fed to voles in the laboratory. Browsing by a natural population of voles amongst winter-dormant willows was measured in the field. In the laboratory, voles browsed on 80% of the twigs and in the field voles browsed on 33% of the twigs. Vole feeding followed similar patterns in the field and in the laboratory experiment; feeding was clearly higher amongst the plants grown in unmulched control compared to those in plastic mulch. The same clones, 1, 2 and 6 were preferred in both experiments. Voles preferred thin twigs to thick ones. Feeding correlated negatively with concentrations of salicylates and tannins. As vole feeding seems to be highly affected by willow cultivation method and plant genotype, careful selection of cultivated clones and cultivation methods can enhance the reliability of herbal willow cultivation.

Effect of Intravenous Albumin Infusion on Brain Salicylate Concentration

Salicylate poisoning appears to result in death, despite supportive care, once a critical brain salicylate concentration is reached. The binding of salicylate to albumin is saturable; free plasma salicylate concentrations rise disproportionately to total drug levels. Because unbound salicylate distributes into the brain, the authors questioned whether an intravenous (i.v.) infusion of albumin would cause a redistribution of salicylate from the brain back into the plasma, which might allow enough time for hemodialysis to be instituted. To determine if i.v. albumin infusion would lower brain salicylate concentrations through redistribution in a porcine model of acute salicylate poisoning. In a randomized controlled trial, 17 swine under anesthesia and controlled ventilation received 400 mg/kg of sodium salicylate i.v. over 15 minutes. At 60 minutes, nine animals received 1.25 g/kg albumin (25% solution) i.v. over 15 minutes, while eight control animals received an equal volume of normal saline (5 mL/kg). Arterial pH was maintained between 7.45 and 7.55. Serial measurements of serum albumin as well as free and total salicylate concentrations were obtained, and urine was collected for measurement of total salicylate excretion. At 180 minutes, animals were killed and brains harvested for measurement of brain salicylate concentrations. Average peak serum total salicylate concentrations of 105.5 and 109 mg/dL were achieved in control and albumin-treated animals, respectively. Albumin infusion was accompanied by statistically significant increases in serum total salicylate concentrations (median from 79.5 to 86.9 mg/dL at 75 minutes), while levels decreased slightly in control animals. Serum free salicylate concentrations decreased slightly in albumin-treated animals, but the difference was not statistically significant. Median brain salicylate concentrations were about 14% lower in the albumin treatment group (17.8 mg/100 g brain) compared with controls (20.5 mg/100 g brain); this approached statistical significance (p = 0.075). Median urinary salicylate excretion was higher in the albumin-treated group (0.83 vs. 0.48 g; p = 0.072), with similar urinary pH and volumes in both groups. In this animal model of salicylate poisoning, i.v. infusion of 1.25 g/kg albumin was accompanied by a 14% decline in median brain salicylate concentrations, which approached statistical significance.

Attenuation of acute plasma cortisol response in calves following intravenous sodium salicylate administration prior to castration

Pain associated with castration in cattle is an animal welfare concern in beef production. This study examined the effect of oral aspirin and intravenous (i.v.) sodium salicylate on acute plasma cortisol response following surgical castration. Twenty bulls, randomly assigned to the following groups, (i) uncastrated, untreated controls, (ii) castrated, untreated controls, (iii) 50 mg/kg sodium salicylate i.v. precastration and (iv) 50 mg/kg aspirin (acetylsalicylic acid) per os precastration, were blood sampled at 3, 10, 20, 30, 40, 50 min and 1, 1.5, 2, 4, 6, 8, 10 and 12 h postcastration. Samples were analyzed by competitive chemiluminescent immunoassay and fluorescence polarization immunoassay for cortisol and salicylate, respectively. Data were analyzed using noncompartmental analysis, a simple cosine model, anova and t-tests. Intravenous salicylate V(d(ss)) was 0.18 L/kg, Cl(B) was 3.36 mL/min/kg and t(1/2 lambda) was 0.63 h. Plasma salicylate concentrations above 25 microg/mL coincided with significant attenuation in peak cortisol concentrations (P = 0.029). Peak salicylate concentrations following oral aspirin administration was <10 microg/mL and failed to attenuate cortisol response. Once salicylate concentrations decreased below 5 microg/mL, cortisol response in the castrated groups was significantly higher than uncastrated controls (P = 0.018). These findings have implications for designing drug regimens to provide analgesia during routine animal husbandry procedures.

Degradation kinetics of hydrolytically susceptible drugs in O/W emulsions—Effects of interfacial area and lecithin

To investigate the influence of the interfacial area and the emulsifier lecithin on the degradation rate of drugs prone to hydrolysis in parenteral lipid O/W emulsions we measured the degradation kinetics of phenyl salicylate in systems consisting of Miglyol as oil, buffered and isotonized aqueous phase and lecithin as emulsifier. Two-layer oil over water systems and emulsions of different oil droplet diameters and emulsifier contents were tested and a kinetic model was developed to interpret the results. The measurements showed a complex influence of interfacial area and liposomal concentration on the hydrolysis of phenyl salicylate. The interface between oil and water does not act as a diffusion barrier for phenyl salicylate, neither without nor with an interfacial layer of emulsifier. However, the presence of the layer and the formation of liposomes by the emulsifier lead to an overall acceleration of the hydrolysis. Three effects, partially counteracting each other, could be distinguished: the increase of phenyl salicylate concentration in the aqueous phase with increasing emulsifier concentration, the acceleration of hydrolysis with increasing interfacial area and the protection from hydrolysis by incorporation of phenyl salicylate into the emulsifier liposomes.

Plasma concentrations of sodium salicylate in nursery pigs treated orally

Plasma concentrations of sodium salicylate in nursery pigs treated orally

Salicylates Trigger Protein Synthesis Inhibition in a Protein Kinase R-like Endoplasmic Reticulum Kinase-dependent Manner

The non-steroidal anti-inflammatory drug aspirin and its metabolite, sodium salicylate, have profound effects on cellular protein synthesis and cell physiology. However, the underlying mechanism by which they cause these responses remains unclear. We show here that salicylates induce phosphorylation of the alpha-subunit of eukaryotic translation initiation factor 2 (eIF2alpha), resulting in the inhibition of mRNA translation in cells. Exposure of cells to acetyl salicylic acid resulted in strong activation of eIF2alpha stress-activated protein kinase R-like endoplasmic reticulum kinase (PERK). Analysis of fibroblasts with a targeted deletion of the perk gene revealed that PERK is indispensable for triggering the phosphorylation of eIF2alpha as well as the inhibition of protein synthesis induced by salicylates. Although salicylate treatment did not trigger activation of inositol-requiring enzyme 1, there was an increased expression of the pro-apoptotic transcription factor CHOP-(gadd153), a downstream event to eIF2alpha phosphorylation known to mediate endoplasmic reticulum stress-mediated responses. Thus, salicylates selectively trigger an endoplasmic reticulum stress-responsive signaling pathway initiated through activation of PERK to induce their cellular effects.

Characterization of transepithelial transport of salicylate by the Malpighian tubules of Drosophila melanogaster and the effects of changes in fluid secretion rate

Abstract A radioisotope tracer technique is used to study mechanisms and regulation of transepithelial transport of the plant allelochemical salicylate by the Malpighian tubules of Drosophila melanogaster. Transepithelial transport of salicylate is nearly abolished in Na+‐free saline, and inhibited by ouabain, low K+ or K+‐free bathing saline. In addition, the carboxylates probenecid, unlabelled salicylate, fluorescein, and p‐aminohippuric acid (PAH) significantly inhibit transepithelial transport of salicylate. The sulphonates taurocholate and phenol red also inhibit transepithelial transport of salicylate, whereas amaranth has no effect. Stimulation of fluid secretion by cAMP, cGMP or leucokinin I increases transepithelial transport of salicylate, particularly when the concentration of salicylate in the bathing saline is high. The correlation between the fluid secretion rate and transepithelial transport of salicylate shows that 64% of the changes in salicylate transport can be explained on the basis of changes in fluid secretion rate. The results show that naturally‐occurring plant secondary metabolite salicylate is transported into the lumen of the Mapighian tubules of D. melanogaster by a mechanism similar to that previously described for the prototypical organic anions PAH and fluorescein. In addition, the transepithelial transport of salicylate increases in response to increases in fluid secretion rate.

Are one or two dangerous? Methyl salicylate exposure in toddlers

Serious toxicity can result from exposure to small amounts of methyl salicylate. Methyl salicylate is widely available as a component in many over-the-counter brands of creams, ointments, lotions, liniments and medicated oils intended for topical application to relieve musculoskeletal aches and pains. Among the most potent forms of methyl salicylate is oil of wintergreen (98% methyl salicylate). Other products with varying concentrations of methyl salicylate are ubiquitous throughout many parts of the world, including a number of products marketed as Asian herbal remedies. The toxic potential of all of these formulations is often underestimated by health care providers and the general public. A comprehensive review of the existing medical literature on methyl salicylate poisoning was performed, and data compiled over the past two decades by the American Association of Poison Control Centers (AAPCC) was examined. Methyl salicylate continues to be a relatively common source of pediatric exposures. Persistent reports of life-threatening and fatal toxicity were found. In children less than 6 years of age, a teaspoon (5 mL) or less of oil of wintergreen has been implicated in several well-documented deaths. More needs to be done to educate both health care providers and the general public regarding the dangers of these widely available formulations.

Potentiometric coated wire electrode for salicylate based on zinc(II) acetylacetonate

A coated-wire ion selective electrode based on zinc(II) acetylacetonate as ionophore exhibited linear response with Nernstian slope of -59.6 ± 1.0 mV/decade over a wide concentration range (1.0´10-5-1.0´10-1 mol L-1). This electrode has 5.0´10-6 mol L-1 detection limit. The proposed electrodes has a response time between 5-10 s to achieve a 95% steady potential for salicylate concentrations. The electrode was suitable for use in aqueous solutions in a wide pH range of 2.7 to 7.8. The electrode life time was tested over a period of two months to investigate its stability. No significant change in the performance of the electrode was observed during this period, but after two months, a gradual decrease ocurred in the slope. The proposed electrode showed high selectivity for salicylate over a number of common inorganic and organic anions. The electrode was successfully applied to the determination of salicylate in pharmaceutical samples.

Non-steroidal anti-inflammatory drugs disrupt the heat shock response in rainbow trout

Non-steroidal anti-inflammatory drugs (NSAIDS) have been detected in the aquatic environment, but little is known about either their impact or mode of action in aquatic organisms. We tested the hypothesis that NSAIDs disrupt the evolutionarily conserved heat shock response, critical for defense against stressor-mediated proteotoxicity, in rainbow trout ( Oncorhynchus mykiss). Trout fry were exposed by immersion to a range of salicylate or ibuprofen concentrations (1, 10, 100 or 1000 μg/L) for 4 d. Ibuprofen, but not salicylate, at all concentrations induced heat shock protein 70 (hsp70) in trout liver. We used the highest concentration of the drugs to investigate their mode of action on the heat shock response. Fry were subjected to a standardized heat shock, 10 °C above ambient (13 °C) for 1 h, and the temporal changes in liver hsp70 mRNA and protein content as well as glucose dynamics during recovery from the heat stressor assessed. Ibuprofen exposure did not modify hsp70 mRNA abundance, but significantly depressed the heat shock-induced hsp70 protein expression in the liver and gill of trout. Salicylate exposure elevated hsp70 mRNA abundance and delayed the hsp70 expression after a heat shock. Liver glucose levels and the activities of hexokinase, pyruvate kinase and lactate dehydrogenase, were elevated by NSAIDs suggesting enhanced tissue glycolytic capacity. Effects on whole body glucose dynamics, induced by the heat shock, were either absent with ibuprofen or completely modified by salicylate. Overall, NSAIDs disrupt the heat shock response in rainbow trout, while the mode of action of salicylate and ibuprofen in impacting the cellular stress response appears distinct.

Suppression by ABA of salicylic acid and lignin accumulation and the expression of multiple genes, in Arabidopsis infected with Pseudomonas syringae pv. tomato

Abscisic acid (ABA) has been implicated in determining the outcome of interactions between many plants and their pathogens. We had previously shown that increased concentrations of ABA within leaves of Arabidopsis induced susceptibility towards an avirulent strain of Pseudomonas syringae pathovar (pv.) tomato. We now show that ABA induces susceptibility via suppression of the accumulation of components crucial for a resistance response. Lignin and salicylic acid concentrations in leaves were increased during a resistant interaction but reduced when plants were treated with ABA. The reduction in lignin and salicylic acid production was independent of the development of the hypersensitive response (HR), indicating that, in this host-pathogen system, HR is not required for resistance. Genome-wide gene expression analysis using microarrays showed that treatment with ABA suppressed the expression of many defence-related genes, including those important for phenylpropanoid biosynthesis and those encoding resistance-related proteins. Together, these results show that resistance induction in Arabidopsis to an avirulent strain of P. syringae pv. tomato is regulated by ABA.

Correlation between the analgesic and antipyretic effects of aspirin and salicylic acid concentration in rabbits

Correlation between the analgesic and antipyretic effects of aspirin and salicylic acid concentration in rabbits

Specificity of Phenolic Glycoside Induction in Willow Seedlings (Salix sericea) in Response to Herbivory

Salix sericea (Marsh.) (Salicaceae) seedlings were used to investigate phytochemical induction of phenolic glycosides following beetle herbivory. Seven-week-old full-sibling seedlings were subjected to one of three damage treatments: Plagiodera versicolora adults, P. versicolora larvae, or Calligrapha multipunctata bigsbyana adults. Salicylate concentrations were measured locally (within damaged leaves) and systemically (above and below damaged leaves) 4 d later. Herbivory caused differential salicylate induction; 2'-cinnamoylsalicortin was induced, whereas salicortin was not. The induction of 2'-cinnamoylsalicortin was not specific with regard to the species or developmental stage of beetle tested but did vary with leaf age: induction occurred in the younger undamaged leaves but not in the damaged leaves or in the older undamaged leaves. The amount of leaf area consumed had no detectable effect on induction, indicating an "all-or-none" response triggered by even small amounts of herbivory. Locally, herbivory caused a decrease in salicortin concentrations, probably because of degradation within the damaged leaves. These results suggest a specific but generalized induced response to these leaf-feeding beetles.

Influence of particle size on the quantitative determination of salicylic acid in a pharmaceutical ointment using FT-Raman spectroscopy

A second order polynomial calibration model was developed and statistically validated for the direct and non-destructive quantitative analysis – without sample preparation – of the active pharmaceutical ingredient (API) salicylic acid in a pharmaceutical ointment using FT-Raman spectroscopy. The calibration curve was modeled by plotting the peak intensity of the vector normalized spectral band between 757 and 784 cm −1 against the known salicylic acid concentrations in standards. At this band, no spectral interferences from the ointment vehiculum (white vaseline) are observed. For the validation of the polynomial model, its fit and its predictive properties were evaluated. The validated model was used for the quantification of 25 ointments, compounded by different retail pharmacists. The same standards and samples were used, both for development and validation of a regression model and for quantitative determination by HPLC – with sample preparation – as described for the related substances of salicylic acid in the Ph. Eur. IV. The quantification results obtained by the FT-Raman method corresponded with the HPLC results ( p = 0.22), provided that the particle size of salicylic acid in the standards is the same as in the analyzed samples. The non-destructive FT-Raman method is a reliable alternative for the destructive HPLC method, as it is faster and does not require sample pre-treatment procedures.

Direct determination of closely overlapping drug mixtures of diflunisal and salicylic acid in serum by means of derivative matrix isopotential synchronous fluorescence spectrometry

A direct method for the simultaneous fluorimetric determination of two anti-inflammatory drugs in serum is proposed. The combination of matrix isopotential synchronous fluorescence (MISF) and first derivative technique provides good analytical results and permits the simultaneous determination of diflunisal and salicylic acid in human serum. MISF spectra are obtained by calculating the isopotential trajectory in the three-dimensional fluorescence spectrum for a serum solution. In the spectral contour, the trajectory is taken to be the portion of the line that passes by the fluorescence maxima of both compounds ensuring a sensitivity level similar to that of a direct determination in absence of background fluorescence. Analysis was carried out in water using a pH of 7.2 provides by 0.1 M sodium dihydrogen phosphate buffer. Serum samples are diluted 100 times and provide linear calibration plots at diflunisal and salicylic acid concentrations up to 800 ng mL −1. The goodness of the analytical signal was checked by using variance analysis. Signals recorded throughout the calibration range were subjected to three calibrations per each analyte, both in the absence and in the presence of variable amounts of the other analyte. Differences between individual calibrations and slopes were compared with those within individual calibrations. Based on the results, diflunisal and salicylic acid can be accurately quantified in the presence of each other. The limit of detection calculated according to Clayton who uses error propagation throughout the calibration curve and a non-centralized security factor was 36.8 and 37.3 ng mL −1 for diflunisal and salicylic acid, respectively.

Therapeutic levels of aspirin and salicylate directly inhibit a model of angiogenesis through a Cox‐ independent mechanism

A range of antineoplastic properties is attributed to aspirin, thought to be due to inhibition of cyclooxygenase (Cox) enzymes in tumor cells. One important outcome is that by reducing angiogenic factor secretion by cancer cells, aspirin also inhibits angiogenesis, thereby restricting tumor growth. However, aspirin may also have direct effects on endothelial cells to regulate angiogenesis. Our aim was to quantitate these effects and determine whether they occurred through inhibiting Cox enzymes. The effects of aspirin, salicylate (the natural deacetylated form of aspirin), and the selective Cox inhibitors SC560 and Celecoxib on endothelial cell proliferation, viability, and angiogenesis were compared. Therapeutic aspirin concentrations (0.5 mM) had no detectable effect on endothelial cell viability or proliferation but caused a striking reduction in tubule formation in a three-dimensional collagen angiogenesis assay. This was also seen with equimolar concentrations of salicylate, while selective Cox inhibitors did not inhibit angiogenesis in this assay either alone or in combination. Furthermore, high doses of aspirin or salicylate (5 mM), well above therapeutic plasma concentrations, lead to endothelial cell apoptosis. We conclude that aspirin, at therapeutic concentrations, directly inhibits angiogenesis via a Cox-independent mechanism, which may significantly contribute to its neoplastic protective effects.

Preadministration of High-Dose Salicylates, Suppressors of NF-κB Activation, May Increase the Chemosensitivity of Many Cancers: An Example of Proapoptotic Signal Modulation Therapy

NF-kappaB activity is elevated in a high proportion of cancers, particularly advanced cancers that have been treated previously. Cytotoxic treatment selects for such up-regulation inasmuch as NF-kappaB promotes transcription of a large number of proteins that inhibit both the intrinsic and extrinsic pathways of apoptosis; NF-kappaB also boosts expression of mdr1, which expels many drugs from cells. Indeed, high NF-kappaB activity appears to be largely responsible for the chemo- and radioresistance of many cancers. Thus, agents that suppress NF-kappaB activity should be useful as adjuvants to cytotoxic cancer therapy. Of the compounds that are known to be NF-kappaB antagonists, the most practical for current use may be the nonsteroidal anti-inflammatory drugs aspirin, salicylic acid, and sulindac, each of which binds to and inhibits Ikappa kinase- beta, a central mediator of NF-kappa activation; the low millimolar plasma concentrations of salicylate required for effective inhibition of this kinase in vivo can be achieved with high-dose regimens traditionally used to manage rheumatic disorders. The gastrointestinal toxicity of such regimens could be minimized by using salsalate or enteric-coated sodium salicy-late or by administering misoprostol in conjunction with aspirin therapy. Presumably, best results would be seen if these agents were administered for several days prior to a course of chemo- or radiotherapy, continuing throughout the course. This concept should first be tested in nude mice bearing xenografts of chemoresistant human tumors known to have elevated NF-kappa activity. Ultimately, more complex adjuvant regimens can be envisioned in which salicylates are used in conjunction with other NF-kappa antagonists and/or agents that target other mediators of down-regulated apoptosis in cancer, such as Stat3; coadministration of salicylate and organic selenium may have intriguing potential in this regard. These strategies may also have potential as adjuvants to metronomic chemotherapy, which seeks to suppress angio-genesis by targeting cycling endothelial cells in tumors.

Quantitative assessment of seminal vesicle and prostate drug concentrations by use of a noninvasive method

The male genital tract is a complex collection of anatomically and biochemically distinct compartments that contribute to the ejaculate. Understanding the pharmacokinetics in these compartments should inform rational therapeutics involving these glands. Nineteen men were administered a single dose of 600 mg chloroquine (base) and 975 mg aspirin before providing a semen sample by masturbation with fractionation into a 5-compartment collection device. Fractions were assayed for fructose (unique seminal vesicle marker), prostate-specific antigen (unique prostate marker), salicylate, and chloroquine. Seminal vesicle and prostate concentrations of salicylate and chloroquine were estimated via a novel analytic method involving a multilevel latent-variable model implemented by use of Bayesian methods. The geometric mean chloroquine semen/blood ratio was 4.02 (95% confidence interval [CI], 2.36-6.86); for salicylate, the primary metabolite of aspirin, the semen/blood ratio was 0.10 (95% CI, 0.08-0.14). The estimated mean prostate/seminal vesicle ratio for salicylate, 0.38 (95% CI by Bayesian methods, 0.12-0.73), was consistent with our hypothesis that salicylate would achieve higher concentrations in the seminal vesicle than in the prostate. Chloroquine, however, did not demonstrate a statistically significant seminal vesicle/prostate difference (4.41; 95% CI by Bayesian methods, 0.14-30.52). We successfully demonstrated the quantitative, noninvasive estimation of drug concentrations in the prostate gland fluid distinct from the seminal vesicle fluid using our optimized method of split-ejaculate collection and a novel mixed-effects model with Bayesian estimation. Our methods can be applied to gland-specific quantitation of drugs and other substances of interest, thus enabling pharmacokinetic, pharmacodynamic, and pathophysiologic studies to inform rational therapeutics within different glands of the male genital tract.