Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Finasteride”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 415 records · Page 23Linked to original sources
PubMed1996

Finasteride in the treatment of benign prostatic hyperplasia.

Finasteride is an enzyme inhibitor which blocks the conversion of testosterone by 5 alpha-reductase to dihydrotestosterone, the active androgenic metabolite in the prostate. In a double-blind, placebo-controlled study, 707 patients with moderately symptomatic BPH were treated for 2 years. The study confirmed that treatment significantly improved symptoms, reduced prostate size and increased urine flow rate. Side effects were usually mild. The authors find that finasteride can reverse the natural progression of BPH.

Aged↗
PubMed1995

The efficacy of finasteride in the treatment of symptomatic benign prostatic hyperplasia.

BACKGROUND: Benign prostatic hyperplasia is a common disease in aged men; the standard therapy has surgery. However, candidates for prostatectomy are commonly aged with high surgical risks, for whom medical treatment is preferable choice. METHODS: From February 1994 to April 1994, in total 25 men with symptomatic benign prostatic hyperplasia were enrolled into this prospective study. All patients were treated with finasteride 5 mg per day for six months. RESULTS: Seven patients withdrew from the study, one for exasperated symptoms, three for personal reasons and three patients were excluded because of poor compliance. In total 18 patients completed the six-month therapy and surveillance. The AUA symptom scores improved on average by 6.3 points; prostatic adenoma volume reduced from baseline by 17%, and the serum prostate specific antigen (PSA) level decreased by 35%. No improvement of the rate of urinary flow was noted. Sixty-one per cent of patients had more than 50% improvement in subjective symptom scores, 28 per cent of men showed per cent or greater decrease in prostate volume. However, only one patient showed an increase of 3 mL/s or more in maximal flow rate at the end of study. Six patients reported adverse sexual experiences (impotence in 3, decreased rigidity in 1, and decreased libido in 2) and one had GI upset. CONCLUSIONS: A subset of patients with benign prostatic hyperplasia may benefit from treatment with finasteride. Although most patients experienced subjective improvement, increase in maximal flow rate is unsatisfactory in this preliminary report.

5-alpha Reductase Inhibitors↗
PubMed1996

Influence of diethylstilbestrol, Leuprolelin (a luteinizing hormone-releasing hormone analog), Finasteride (a 5 alpha-reductase inhibitor), and castration on the lobar subdivisions of the rat prostate.

The effects of various means of interfering with androgen action on rat coagulating gland, ventral prostate, lateral type 1 prostate, lateral type 2 prostate, and dorsal prostate were examined morphologically and quantitatively by assessing DNA content, wet weight, protein content, and zinc concentrations. Adult male Sprague-Dawley rats were subjected to 2 weeks of interfering with androgen action by treatment with Leuprolelin (a luteinizing hormone-releasing hormone analog), Finasteride (a 5 alpha-reductase inhibitor), or diethylstilbestrol (DES), or by physical castration. For all prostatic lobes, inhibition of 5 alpha-reductase elicited the smallest reduction in prostatic wet weight, DNA and protein contents, and zinc concentration. The most profound reductions in all parameters were elicited by castration. Treatments with DES and Leuprolelin gave intermediate effects with DES being the more effective in reducing all parameters in all prostatic lobes. Morphological changes elicited by all forms of androgen blockade were reduction of epithelial height, relative increase of connective tissue, reduction in ductal diameter, length, and number. The order of effectiveness of the various treatments on morphological features was as described above. While all forms of androgen blockade elicited similar effects throughout the prostate, differences in response to all forms of interference with androgen action were observed in different lobes of the prostate with regard to wet weight, DNA and protein contents, and zinc concentration as well as morphological effects. Regressive changes at the morphological level were particularly striking in the coagulating gland and ventral prostate, and indistinct in the lateral type 2 prostate. Prostatic zinc concentration in both normal and androgen-deprived rats was the highest in the lateral type 2 prostate and was reduced by interfering with androgen action to the greatest extent in the dorsolateral prostate (lateral type 1 and type 2, and dorsal prostate). The distribution of zinc correlated with the expression of metallothionein, which was detected by immunocytochemistry only in the lateral type 2 prostate of both normal and androgen deprived rats. Intraprostatic heterogeneity of zinc and metallothionein expression emphasizes interlobar differences in biological function within the rat prostate. The mechanism of development of regional heterogeneity within the prostate may shed light on the pathogenesis of prostatic proliferative diseases (prostatic hyperplasia and prostatic cancer) that initially owe their development to focal changes within large cell populations.

5-alpha Reductase Inhibitors↗
PubMed2000

Prostatic involution in men taking finasteride is associated with elevated levels of insulin-like growth factor-binding proteins (IGFBPs)-2, -4, and -5 .

BACKGROUND: Insulin-like growth factor-binding proteins (IGFBPs)-2, -4, and -5 are associated with upregulation of apoptosis in the ovary. The purpose of this study was to assess the roles of IGF-I and IGFBPs during involution of the prostate. Frozen and fixed tissue was collected by transurethral prostatectomy from Caucasian men, aged 52-82 years, scheduled for prostatectomy for benign prostatic hyperplasia, who took either placebo (n = 7) or the 5alpha-reductase inhibitor finasteride for 6 days to 6 years (n = 15) prior to surgery. METHODS: Intraprostatic androgen levels were measured by radioimmunoassay. Tissues were immunostained for IGF-I and IGFBP-2, -3, -4, and -5, and staining was quantitated by computerized image analysis. Serial sections were stained for markers of apoptosis (TUNEL and tissue transglutaminase) and IGFBP-2, -4, or -5. RESULTS: IGF-I staining was significantly decreased in the medium-term (18-43 days) treatment group and remained so for the duration of the study (P = 0.026). IGFBP-3 staining was unchanged in the early and medium-term treatment groups; however, a transient earlier rise in the level of this proapoptotic protein cannot be ruled out. The percentage of epithelial cell area staining positively for IGFBP-2 increased significantly, from 1.6 +/- 0.5 in the placebo group to 12.0 +/- 2.0 (P < 0.0001), and 7.6 +/- 1.9 (P = 0.003) in the short (6-13 days) and medium-term treatment groups, respectively. IGFBP-4 staining increased from 2.2 +/- 0.6 to 9.8 +/- 1.9 (P < 0.0001) and 7.4 +/- 1.2 (P = 0.004) in the short and medium-term groups, respectively, and IGFBP-5 staining increased from 0.2 +/- 0.1 to 3.8 +/- 2.0 (P = 0.004) in the medium-term group. The results from serial sections showed that IGFBP-2 and -4 costained with markers of apoptosis, while IGFBP-5 did not. CONCLUSIONS: These results indicate that IGFBP-2, -4, and -5 are associated with prostatic involution. Because of the timing and distribution of expression, we hypothesize that IGFBP-2 and -4 have a role as signals for apoptosis, but that IGFBP-5 likely does not.

Aged↗
PubMed1995

Analyzing finasteride data.

Published data on the safety and efficacy of finasteride in the treatment of benign prostatic hyperplasia are studied and compared with published conclusions. The need for publishing correlation studies of both the benefits and side-effects, to allow for informed physician and patient decisions, is detailed.

Enzyme Inhibitors↗
PubMed1994

TRPM-2 gene expression in normal rat ventral prostate following castration and exposure to diethylstilbestrol, flutamide, MK-906 (finasteride), and coumarin.

TRPM-2, not normally expressed in the rat ventral prostate, has been identified as an important genetic marker of castration-induced apoptotic cell death. It is not known whether other agents capable of causing growth inhibition of the rat ventral prostate also induce TRPM-2 expression. To investigate this further, 270 mature Sprague-Dawley rats were randomized into one of six groups: control, castration, diethylstilbestrol (DES), flutamide, MK-906 (finasteride), or coumarin. Five rats per group were sacrificed on days 1, 3, 5, 7, 10, and 21. Serum testosterone, body weights, and prostate weights were determined at each time point. The ventral prostate was removed and cellular RNA extracted. Northern blot analysis using cDNA probes for TRPM-2 and gamma-actin were performed at each time point. Only DES significantly decreased rat weights. DES and castration reduced serum testosterone to undetectable levels by the next day. Flutamide caused a 3.0- to 4.5-fold increase in serum testosterone above control. Coumarin and MK-906 did not affect serum testosterone levels. DES and castration reduced prostate weights to 20% and 6% of control, respectively, while inducing TRPM-2 expression to a maximum on day 5 of the experiment. DES induced TRPM-2 expression over a longer duration than did castration, suggesting that more than just the decrease of serum testosterone to castrate levels plays a role in the expression of TRPM-2. MK-906, coumarin, and flutamide reduced prostatic weights to a lesser extent (50%, 63%, 71% of control, respectively), but these agents did not induce TRPM-2 expression at any time during the experiment. TRPM-2 expression in the rat ventral prostate does not correlate simply with catabolic effects on the prostate.

Animals↗
PubMed1990

External genitalia abnormalities in male rats exposed in utero to finasteride, a 5 alpha-reductase inhibitor.

A series of studies was conducted to determine the developmental toxicity of the 5 alpha-reductase inhibitor finasteride (MK-0906) in rats. This compound was administered orally once daily to pregnant rats during various extended treatment periods during gestation. F1 offspring were evaluated on Day 20 of gestation as well as postnatally through mating to produce an F2 generation. MK-0906 treatment induced dosage-related incidences of hypospadias (penischisis) in male offspring with a threshold dosage level near 0.1 mg/kg/day and a 100% effect level of 100 mg/kg/day (with dosing through Day 20 of gestation). MK-0906 also caused decreased anogenital distance in male offspring. The dosage response for this effect (ranging from a 4.2% decrease at 0.003 mg/kg/day to a 38% decrease at 100 mg/kg/day) was more shallow than that for hypospadias. The decreases in anogenital distance were at least partially reversible postnatally with essentially complete recovery at dosages up to 0.1 mg/kg/day. There was also a dosage-related, temporary induction of nipples in F1 males. All of these effects were apparent following treatment on Days 6 through 17 of gestation but were more pronounced when dosing extended to Day 20 of gestation. Slight maternal toxicity consisting of minor decreases in body weight gain occurred only at dosages of 3 mg/kg/day and higher, indicating the selective nature of the developmental toxicity. The 5 alpha-reductase enzyme located in the rat fetal genital tubercle was studied in vitro and compared to that in the adult ventral prostate. The values for Km, Vmax, and IC50 for inhibition by MK-0906 were similar in the two tissues, suggesting that the enzymatic proteins in the genital tubercle and ventral prostate may be similar.

5-alpha Reductase Inhibitors↗
PubMed1996

High-performance liquid chromatographic determination of finasteride in human plasma using direct injection with column switching.

A fully automated column-switching high-performance liquid chromatographic (HPLC) method was developed for the quantification of finasteride [N-(1,1-dimethylethyl)-3-oxo-4-aza-5 alpha-androst-1-ene-17 beta- -carboxamide] in human plasma. Plasma samples were diluted with an equal volume of ethylene glycol-water (40:60, v/v), then the diluted sample (150 microliters) was injected into the HPLC system without clean-up. The analyte was retained on a pretreatment column, whereas plasma proteins and other endogenous components were washed out to waste. The analyte was transferred to the analytical column in the heart-cut mode and then detected at 210 nm. A quantification limit of 1 ng/ml was attained. There was a linear relationship between peak height and drug concentration in plasma in the range 1-50 ng/ml. This method was validated and applied to the assay of plasma samples to characterize pharmacokinetic parameters in clinical studies.

Biotransformation↗
PubMed2005

Treatment with and withdrawal from finasteride alter ethanol intake patterns in male C57BL/6J mice: potential role of endogenous neurosteroids?

Exogenous administration of the gamma-aminobutyric acid (GABA)-ergic neurosteroid allopregnanolone (ALLO) can increase ethanol intake in rats and mice. To determine the contribution of endogenous neurosteroids (i.e., ALLO and related pregnane steroids) in the regulation of established ethanol consumption patterns in male C57BL/6J (B6) mice, the 5alpha-reductase (5alpha-R) enzyme inhibitor, finasteride (FIN), was chronically administered and then subsequently withdrawn. Mice were provided daily 2-h limited access to a 10% vol/vol ethanol solution (10E) and water in lickometer chambers during the dark phase. Following the establishment of stable 10E intake patterns, mice were injected intraperitoneally with either vehicle (20% wt/vol 2-hydroxypropyl-beta-cyclodextrin; n=8) or FIN (50 mg/kg; n=16) for 7 days. Effects of withdrawal from FIN treatment were subsequently assessed for an additional 7 days. Ethanol intakes were significantly decreased with acute FIN treatment (days 1-3) and during early withdrawal (days 1-3). Acute FIN treatment was also associated with an extended latency to first bout, reduced first bout size, and greatly attenuated sipper contact count during the initial 20-min interval of 10E access. These findings collectively indicated that acute FIN treatment markedly attenuated the initiation of 10E consumption during the limited access sessions. The influence of FIN on 10E intake patterns was largely dissipated with chronic treatment, suggesting that compensatory changes in neurosteroid modulation of inhibitory tone may have occurred. Thus, acute FIN treatment modulated ethanol intake patterns in a manner opposite to that previously demonstrated for a physiologically relevant, exogenous ALLO dose, consistent with the ability of a alpha-R inhibitor to block ALLO biosynthesis. Manipulation of endogenous neurosteroid activity via biosynthetic enzyme inhibition or antagonism of steroid binding to the GABA type A receptor may prove to be a beneficial pharmacotherapeutic strategy in the intervention of alcohol abuse and alcoholism.

Alcohol Drinking↗
PubMed2006

Deoxycorticosterone's anticonvulsant effects in infant rats are blocked by finasteride, but not by indomethacin.

Deoxycorticosterone (DOC) is a steroid hormone that suppresses seizures in both humans and animals. At higher doses, DOC's anticonvulsant actions are accompanied by sedation and ataxia. The mechanism of DOC's anticonvulsant actions is not known, although it has been suggested that they may relate to DOC's secondary metabolite 3-alpha-5-alpha-tetrahydrodeoxycorticosterone (THDOC). The present study was designed to study the relation of DOC's anticonvulsant actions to its primary and secondary metabolites in 15-day-old rats. It was found that DOC's anticonvulsant and ataxic effects were suppressed by finasteride, which blocks the formation of DOC's primary metabolite, 3-alpha-5-alpha-dehydrodeoxycorticosterone (DHDOC). They were not suppressed by indomethacin (INDO), which blocks the conversion of DHDOC into THDOC. The direct anticonvulsant effects of DHDOC and THDOC were also tested. DHDOC and THDOC were both potent anticonvulsants in 15-day old rats. Both also caused ataxia at high doses. DHDOC had a therapeutic index (TI) of 3.2, however, which was better than either DOC (TI = 1.2) or THDOC (TI = 1.5). It appears that DOC itself is not anticonvulsant, but that its anticonvulsant effects may relate to both its primary and secondary metabolites. DOC's primary metabolite, DHDOC--with its good TI--deserves a test in the treatment of childhood seizures.

Animals↗
PubMed2006

A new spectrophotometric method for the determination of finasteride in tablets.

A simple, rapid, accurate, precise and sensitive colorimetric method for the determination of finasteride in tablets is described. The proposed methods are based on the formation of ion-pair complexes between the examined drug with bromophenol blue (BPB), bromocresol green (BCG) and bromothymol blue (BTB), which can be measured at the optimum lambda(max). Beer's law is obeyed in the concentration ranges 3.0-15.0, 3.0-15.0 and 5.0-20 microg/mL with BPB, BCG and BTB, respectively. The detection limits of FIN was found to be 1.16 microg/mL for BPB, 1.17 for BCG, 1.76 microg/mL for BTB. All the methods gave similar results and were validated for selectivity, linearity, precision and sensitivity. The proposed methods were directly and easily applied to the pharmaceutical preparation with accuracy, resulting from recovery experiments between 100.11 and 100.33% for BPB, 100.17 and 100.67% for BCG and 100.33 and 100.60% for BTB methods. The low relative standard deviation values indicate good precision and high recovery values indicate accuracy of the proposed methods. The proposed methods have been applied to the determination of drug in commercial tablets. Results obtained from the analysis of commercial preparations with the proposed methods are in good agreement with those obtained with the official HPLC method.

Bromphenol Blue↗
PubMedDate not supplied

Plasma androsterone/epiandrosterone sulfates as markers of 5 alpha-reductase activity: effect of finasteride in normal men.

Plasma androsterone/epiandrosterone sulfates, dehydroepiandrosterone sulfate, dihydrotestosterone, testosterone, androstenedione, and cortisol were measured in three normal adult men before and following finasteride administration (5 mg/day). Plasma androsterone/epiandrosterone sulfates and dihydrotestosterone declined in parallel to 50% of basal levels with little change in either dehydroepiandrosterone sulfate, cortisol, or androstenedione. The results suggest that the direct measurement of plasma androsterone/epiandrosterone sulfates by enzyme-linked immunosorbent assay provide similar information to plasma dihydrotestosterone and therefore provide a simple alternative for the assessment of 5 alpha-reductase activity.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed2002

Effects of finasteride and cyproterone acetate on hematuria associated with benign prostatic hyperplasia: a prospective, randomized, controlled study.

OBJECTIVES: To evaluate the influence of two differently acting antiandrogens, finasteride (FIN) and cyproterone acetate (CPA), on the natural history of hematuria associated with benign prostatic hyperplasia (BPH) in a prospective, randomized, controlled study. METHODS: Forty-two patients with hematuria episodes due to BPH were randomly allocated to three subgroups of 14 patients each and treated daily with either 5 mg FIN or 100 mg CPA or were placed in a watchful waiting arm. Patients were evaluated at 3-month intervals, and 40 patients had at least 1 year of follow-up. RESULTS: Four patients in the FIN group (30%) and three in the CPA group (23%) presented with recurrent hematuria. In both groups, the bleeding episodes were treated conservatively and required no hospitalization. In the control group, 8 patients (57%) presented with recurrent bleeding; in 4, the bleeding was severe and required some form of intervention (catheterization or transurethral prostatectomy). When the frequency and severity of the hematuria episodes were analyzed over time, a statistically significant difference for FIN versus control was present at 9 and 12 months (analysis of variance, P = 0.035 and P = 0.009, respectively). A similar difference was evident for CPA versus control at 9 and 12 months (P = 0.028 and P = 0.008, respectively). No statistically significant difference was present between the FIN and CPA groups. Interestingly, no statistically significant effect in bleeding recurrence for both CPA and FIN over controls was present at 3 and 6 months of follow-up. CONCLUSIONS: Both FIN and CPA seem to exert a comparable control in hematuria recurrence in patients with BPH, thus confirming the rationale behind the use of antiandrogens for such a purpose. Our results support the hypothesis that any antiandrogen, irrespective of the mode of action, would alter the natural history of BPH-associated hematuria. Interestingly, our results indicate that the speed of action of FIN may not be as rapid as previously described.

Aged↗
PubMed2002

Study of the association between ischemic heart disease and use of alpha-blockers and finasteride indicated for the treatment of benign prostatic hyperplasia.

OBJECTIVE: Given the high possibility of co-occurrence of benign prostatic hyperplasia (BPH) and cardiovascular disease, we evaluated whether patients using BPH drugs are at an increased risk of acute hospital admission for ischemic heart disease (IHD). METHODS: A nested case control study within a cohort of 4414 men (aged > or =30 years) who had a history of using BPH products between 1992 and 1998 was conducted. Cases were defined as men with a first record of an acute hospital admission for IHD during the study period; three controls were matched to each case on year of birth, pharmacy and calendar time (index date). RESULTS: The study population comprised 220 cases and 515 controls. Current use of alpha-blockers (adjusted odds ratio 1.0, 95% confidence interval: 0.5-2.2) or finasteride (adjusted odds ratio 0.3, 95% CI: 0.1-1.4) was not associated with hospital admission for IHD. Furthermore, current use of BPH drugs was not associated with IHD in patient subgroups (age, history of cardiovascular disease, diabetes), nor with duration of use prior to hospitalization. CONCLUSION: Although the power of the study was low, we found no evidence for an association between current use of BPH drugs and hospital admission for IHD. Therefore, our study seems to confirm the good cardiovascular safety profile of modern BPH drugs.

Adrenergic alpha-Antagonists↗
PubMed2004

Ketocazole as an adjunct to finasteride in the treatment of androgenetic alopecia in men.

Dihydrotestosterone (DHT) binding to androgen receptors (AR) in hair follicles is commonly accepted as the first step leading to the miniaturizing of follicles associated with androgenetic alopecia (AGA). Testosterone is converted to DHT by the enzyme 5alpha-reductase. Finasateride a 5alpha-reducase inhibitor blocks the production of DHT and is currently used to treat AGA. The inhibition is not complete but a reduction of DHT systemically and in the scalp is accomplished. Ketoconazole has been clinically shown to be effective in the treatment of AGA. In this paper, evidence is presented to support the hypothesis that ketoconazole 2% shampoo has a local disruption of the DHT pathway. It is proposed that using ketoconazole 2% shampoo as an adjunct to finasteride treatment could lead to a more complete inhibition of DHT and thus better treat AGA.

Administration, Oral↗
PubMed2000

Determination of finasteride in human plasma by liquid-liquid extraction and high-performance liquid chromatography.

A high-performance liquid chromatographic method for the quantitation of finasteride in human plasma is presented. The method is based on liquid-liquid extraction with hexane-isoamylalcohol (98:2, v/v) and reversed-phase chromatography with spectrophotometric detection at 210 nm. The mobile phase consists of acetonitrile-15 mM potassium dihydrogenphosphate (40:60, v/v). Clobazam is used as the internal standard. The limit of quantitation is 4 ng/ml and the calibration curve is linear up to 300 ng/ml. Within-day and between-day precision expressed by relative standard deviation is less than 5% and inaccuracy does not exceed 8%. The assay was used for pharmacokinetic studies.

Chromatography, High Pressure Liquid↗
PubMed2001

LC determination of finasteride and its application to storage stability studies.

The development of a simple, sensitive, rapid, and reproducible reversed-phase high-performance liquid chromatographic assay of finasteride (proscar) in preformulation, and its application to forced degradation studies has been carried out. The method showed excellent linearity (r2 > or = 0.9997) in the range 20-600 microg x ml(-1) using a Shimpak C8 column (5 microm, 15.0 cm x 4.6 mm) and UV-detection (210 nm) at ambient temperature (25 +/-1 degree C) with a mobile phase of acetonitrile and water (95:05,v/v) and flow rate of 0.7 ml x min(-1). All peaks are eluted in < 10 min and the method has good precision. This method showed good efficiency for the analysis of forced degraded samples, studied at different temperatures and humidities. The results manifest that the shelf-life of proscar is greater than two years at room temperature, under proper storage conditions.

Chromatography, High Pressure Liquid↗
PubMed1998

Matrix effect in quantitative LC/MS/MS analyses of biological fluids: a method for determination of finasteride in human plasma at picogram per milliliter concentrations.

Contrary to common perceptions, the reliability of quantitative assays for the determination of drugs in biological fluids using high-performance liquid chromatography with tandem mass spectrometric (LC/MS/MS) detection methods and the integrity of resulting pharmacokinetic data may not be absolute. Results may be adversely affected by lack of specificity and selectivity due to ion suppression caused by the sample matrix, interferences from metabolites, and "cross-talk" effects. In this paper, an example of the effect of the sample matrix on the determination of finasteride (I) in human plasma is presented. The ion suppression effect was studied by analyzing standards of I injected directly in mobile phase and comparing the response (peak areas) of I and an internal standard (II) with the peak areas of the same analytes spiked before extraction into five different plasma pools and standards spiked into the plasma extracts after extraction. The LC/MS/MS analyses were performed using a turbo ion spray interface (TISP) under chromatographic conditions, characterized by minimal (total run time of 2 min, capacity factors, k' of 1.50 and 1.75 for I and II, respectively) and high retention of the analytes (total run time 6 min, k' of 3.25 and 13.25 for I and II, respectively). The absolute peak areas for I and II in different plasmas were calculated, and the slopes and peak area ratios at all concentrations within the standard curve ranges were compared. When analyses were performed under conditions of minimal HPLC retention, the slope of the standard line for one set of plasma samples was substantially different (about 50% higher) from that from other plasma sources. The precision of the assay, expressed as coefficient of variation (CV, %) was also inadequate and varied from 15 to 30% at all concentrations within the standard curve range. When the same experiments were repeated using high HPLC retention, the slopes from different plasma sources were practically the same, and the CV was improved to 6-14%. By increasing k' and providing more chromatographic retention of analytes, the "unseen" interferences from plasma matrix were mostly separated from analytes, practically eliminating the ion suppression. In addition, by eliminating from plasma extracts a number of endogenous components through more selective extraction, the ion suppression was also minimized. The detailed data and the design of these experiments are presented. In addition, development of a highly sensitive assay for I in human plasma at low picogram per milliliter concentrations using LC/MS/MS with a heated nebulizer (HN) interface, instead of a TISP interface, is described. In this case, the effects of sample matrixes were not observed.

Chromatography, High Pressure Liquid↗