Efficacy and safety of sacubitril valsartan in heart failure compared to renin angiotensin aldosterone system inhibitors: a systematic review and meta analysis of randomised controlled trials

Background

Benefits and harms of the use of LCZ696 (sacubitril/valsartan, S/V), a combination of a neprilysin inhibitor and an angiotensin receptor blocker (ARB), in heart failure (HF) are unknown.

Purpose

To systematically assess benefits and harms of S/V as compared to angiotensin converting enzyme inhibitors (ACEI) or ARB in patients with HF.

Methods

We searched for randomised controlled trials (RCTs) evaluating S/V vs. ACEI or ARB in acute or chronic HF adult patients. Primary outcomes were HF hospitalisation and cardiovascular [CV] mortality; secondary outcomes were all-cause mortality, decline in renal function, myocardial dysfunction, quality of life (QoL), systolic blood pressure (SBP), diastolic blood [DBP], and adverse events (AEs) including worsening renal function (SCr≥2 mg/dL), hyperkalaemia (K+≥5.5 mmol/L), symptomatic hypotension (SBP<100 mmHg), and angio-oedema. Inverse variance random-effects meta-analyses were conducted and effects expressed as hazard ratios (HR), relative risks (RR) or mean difference (MD) and their 95% confidence intervals (CI). GRADE methodology was used to assess the certainty of evidence (CoE).

Results

We selected 11 RCTs (n=18766). Follow-up times ranged between 2 and 48 months; the average age of participants was 61 to 73 years-old. Five RCTs had ACEIs as control, five RCTs had ARBs as control, and one RCT had both ACEI and ARB as control. Six RCTs had low risk of bias; five RCTs had unclear risk of bias. S/V reduced the hazard of HF hospitalisations by 20% (HR 0.80, 95% CI 0.68–0.94; 3 RCTs; I2=65%; high CoE), CV mortality by 14% (HR 0.86, 95% CI 0.73 to 1.01; 2 RCTs; I2=57%; high CoE) and all-cause mortality by 11% (HR 0.89, 95% CI 0.78–1.00; 3 RCTs; I2=36%; high CoE) compared to ACEI or ARB control (Figure 1). S/V slightly improved KCCQ-QoL scores (MD 1.36 points, 95% CI 0.49 to 2.24; 6 RCTs; I2=54%). S/V did not affect LVEF and E/E' but reduced NTproBNP (SMD −0.34, 95% CI −0.52 to −0.16; 3 RCTs; I2=62%), and hs-TNT (Ratio of differences 0.84, 95% CI 0.79–0.88; 2 RCTs; I2=0%). SBP and DBP were reduced by 4 mmHg and 3 mmHg, respectively, and hypotension was increased (RR 1.69, 95% CI 1.33–2.15; 9 RCTs; I2=65%; high CoE) with S/V. Also, S/V reduced the hazard of decline in renal function by 33% (HR 0.67, 95% CI 0.39–1.14; 2RCTs; I2=78%; high CoE); hyperkalaemia and angioedema events were similar between S/V and controls.

Conclusions

Sacubitril/valsartan had better clinical and intermediate outcomes in HF in comparison to ACEI or ARB. Decline of renal function was less frequent with S/V in comparison to controls, and there was no difference in decline of renal function or angioedema and hyperkalaemia events. However, sacubitril/valsartan was associated with more symptomatic hypotension events vs. controls.

Funding Acknowledgement

Type of funding sources: None.

Effects of sacubitril valsartan on renal function in adults with heart failure: a systematic review and meta analysis of randomised controlled trials

Background

Sacubitril/valsartan (S/V) may have beneficial effects on renal outcomes in patients with heart failure (HF) receiving angiotensin-converting enzyme inhibitors (ACEI) or angiotensin II receptor blockers (ARB).

Purpose

To systematically evaluate the effects of sacubitril/valsartan on renal function in adults with HF.

Methods

Five databases were searched for randomised controlled trials (RCTs) comparing S/V (LCZ696) vs. ACEI or ARB in adult HF patients until January 2022. Doubling serum creatinine levels was the primary outcome. Acute kidney injury (AKI)>50% decline of estimated glomerular filtration rate (eGFR), and hyperkalaemia (serum K+ >5.5 mmol/L) were secondary outcomes. Inverse variance random-effects meta-analyses were used, and effects of S/V on outcomes were described with relative risks (RR) and their 95% confidence intervals (CI). Subgroup analyses by type of HF (chronic vs. acute), and LVEF (<40% vs >40%) were performed. We used the RoB 2.0 tool for risk of bias assessments of RCTs. GRADE methods were used to rate the certainty of evidence (CoE).

Results

Eight RCTs (n=15859) were included; four in chronic HF and four in acute HF. Mean age was 66.2 (SD 5.5) years-old, and 34.1% were female. The median follow-up across RCTs was 36 weeks. In comparison to ACEI/ARB, S/V was associated with lower risk of doubling serum creatinine (RR 0.77; 95% CI 0.72–0.83; I2=0%; moderate CoE). S/V did not reduce the risk of AKI (RR 0.88; 95% CI 0.72–1.08; I2=0%; low CoE), >50% decline of eGFR (RR 0.65; 95% CI 0.37–1.17; I2=45%; very low CoE), and hyperkalaemia (RR 1.01; 95% CI 0.81–1.25; I2=44%; very low CoE). Two RCTs had high risk of bias and two had some concerns of bias. Subgroup analyses were consistent with main analyses for the primary outcome.

Conclusions

In adults with heart failure, S/V reduced doubling creatinine compared to ACEI/ARB, but did not reduce risks of AKI, >50% decline in eGFR or hyperkalaemia. Subgroup analyses by type of HF and LVEF were consistent with main analyses.

Funding Acknowledgement

Type of funding sources: None.

Efficacy and safety of colchicine after myocardial infarction: a systematic review and meta- analysis

Background

Inflammation plays a key role in atherosclerotic plaque destabilization and adverse cardiac remodeling. Recent evidence has shown a promising role of colchicine in patients with coronary artery disease.

Purpose

We evaluated the efficacy and safety of colchicine in post-acute myocardial infarction (MI) patients.

Methods

We searched five electronic databases from inception to January 18, 2021, for randomized controlled trials (RCTs) evaluating colchicine in post-acute MI patients. Primary outcomes were cardiovascular mortality and recurrent MI. Secondary outcomes were all-cause mortality, stroke, urgent coronary revascularization, levels of follow-up high-sensitivity C-reactive protein (hs-CRP), and drug-related adverse events. All meta-analyses used inverse-variance random-effects models.

Results

Six RCTs (n=6005) patients were included. Colchicine did not significantly reduce cardiovascular mortality (risk ratio [RR], 0.91; 95% confidence interval [95% CI], 0.52–1.61; p=0.64), recurrent MI (RR, 0.87; 95% CI, 0.62–1.22; p=0.28), all-cause mortality (RR, 1.06; 95% CI, 0.61–1.85; p=0.78), stroke (RR, 0.28; 95% CI, 0.07–1.09; p=0.05), urgent coronary revascularization (RR, 0.46; 95% CI, 0.02–8.89; p=0.19), or decreased levels of follow-up hs-CRP (MD, −1.95 mg/L; 95% CI, −12.88 to 8.98; p=0.61) compared to the control group. There was no increase of any adverse event (RR, 0.97; 95% CI, 0.89–1.07; p=0.34) or gastrointestinal adverse events (RR, 2.49; 95% CI, 0.48–12.99; p=0.20). Subgroup analyses by colchicine dose (0.5 versus 1 mg/day), time of follow-up (<1 versus ≥1 year), and treatment duration (≤30 versus >30 days) showed no changes in the overall findings.

Conclusion

In post-acute MI patients, colchicine does not reduce cardiovascular or all-cause mortality, recurrent MI, or other cardiovascular outcomes. Also, colchicine did not increase drug-related adverse events.

Funding Acknowledgement

Type of funding sources: None.

Effect of mediterranean diets on cardiovascular risk factors and diseases in the primary prevention setting: a systematic review and meta-analysis of randomized controlled trials

Background

The effects of Mediterranean diets (MED) on various health parameters suggest potential cardiovascular (CV) health benefits.

Purpose

We evaluated the effects of MED for primary prevention of CV risk factors and disease in overweight or obese adults.

Methods

A systematic review and meta-analysis of randomized controlled trials (RCTs) was performed using PRISMA guidelines. PubMed, EMBASE, Web of Science, Scopus, Cochrane Library, clinicaltrials.gov, and clinicaltrialsregister.eu were searched until January 2020. RCTs evaluating any type of MED compared to other diets or advice in adults were included. Predefined CV risk factors were lipid, liver, glucose, anthropometric, and blood pressure outcomes. Clinical outcomes were all cause mortality, CV mortality, myocardial infarction (MI), coronary artery disease, stroke, cerebrovascular disease, and diabetes. Meta-analyses of random effects models were performed and effects were described as mean difference (MD) and their 95% confidence intervals (CI). Subgroup analyses by weight, type of MED, type of control, and trial duration were performed when heterogeneity was high (I2>60%).

Results

Eighteen RCTs (n=915) were included. Two RCTs evaluated only obese patients, 13 evaluated overweight and obese patients, and three did not specify. Fifteen RCTs evaluated MED alone while three evaluated MED combined with another diet. Thirteen RCTs evaluated effects of another diet while five evaluated diet advice or no treatment as controls. The median time to follow up was 6 months (range 6 weeks to 24 months). Clinical outcomes were only described in the revised 2018 PREDIMED trial where MED were associated with 35% lower risk of MI, stroke, and CV death vs advice (HR 0.65, 95% CI 0.50 to 0.85). MED were significantly associated with lower levels of triglycerides (TG) (MD −12.70 mg/dL, 95% CI −18.58 to −6.82), waist circumference (WC) (MD −1.92 cm, 95% CI −3.59 to −0.24), weight (MD −1.75 kg, 95% CI −2.82 to −0.69), and body mass index (BMI) (MD −0.69 kg/m2, 95% CI −1.11 to −0.27), and higher levels of HDL (MD 2.03 mg/dL, 95% CI 1.13 to 2.92) compared to other diets or advice. MED did not significantly change any other CV risk factors. Subgroup analyses showed some differences vs main analyses, but were based on a small set of RCTs in most of cases. Excluding five high risk of bias RCTs showed significant reductions in total cholesterol (MD −6.57 mg/dL, 95% CI −12.22 to −0.93), Fatty Liver Index (MD −23.30, 95% CI −30.20 to −16.40), HOMA-IR (MD −0.53, 95% CI −1.02 to −0.05), and SBP (MD −2.35 mmHg, 95% CI −4.02 to −0.68).

Conclusion

MED significantly decreased TG and anthropometric outcomes, and increased HDL when compared to other diets or advice. There was no significant association between MED and the other predefined CV risk factors. Newer RCTs without the flaws of PREDIMED are needed to further evaluate clinical outcomes.

Funding Acknowledgement

Type of funding source: None

Obesity-related insulin resistance in adolescents: a systematic review and meta-analysis of observational studies

Insulin resistance is common among obese adolescents; however, the extent of this problem is not clear. We conducted a systematic review of PubMed-Medline, CINAHL, The Web of Science, EMBASE and Scopus for observational studies evaluating components defining insulin resistance (insulin, C-peptide and homeostatic model assessment-insulin resistance [HOMA-IR]) in obese adolescents (12-18 years) versus non-obese adolescents. Our systematic review and meta-analysis followed the PRISMA guidelines. Data were combined using a random-effects model and summary statistics were calculated using the mean differences (MDs). 31 studies were included (n = 8655). In 26 studies, fasting insulin levels were higher in obese adolescents when compared to non-obese adolescents (MD = 64.11 pmol/L, 95%CI 49.48-78.75, p < 0.00001). In three studies, fasting C-peptide levels were higher in obese adolescents when compared to non-obese adolescents (MD = 0.29 nmol/L, 95%CI 0.22-0.36, p < 0.00001). In 24 studies, HOMA-IR values were higher in obese adolescents when compared to non-obese adolescents (MD = 2.22, 95%CI 1.78-2.67, p < 0.00001). Heterogeneity of effects among studies was moderate to high. Subgroup analyses showed similar results to the main analyses. Circulating insulin and C-peptide levels and HOMA-IR values were significantly higher in obese adolescents compared to those non-obese.

A systematic review and meta-analysis of the relative efficacy and safety of treatment regimens for HIV-associated cerebral toxoplasmosis: is trimethoprim-sulfamethoxazole a real option?

OBJECTIVES

The objective of this study was to perform a systematic review and meta-analysis of the literature to evaluate the efficacy and safety of therapies for cerebral toxoplasmosis in HIV-infected adults. The pyrimethamine plus sulfadiazine (P-S) combination is considered the mainstay therapy for cerebral toxoplasmosis and pyrimethamine plus clindamycin (P-C) is the most common alternative treatment. Although trimethoprim-sulfamethoxazole (TMP-SMX) has potential advantages, its use is infrequent.

METHODS

We searched PubMed and four other databases to identify randomized controlled trials (RCTs) and cohort studies. Two independent reviewers searched the databases, identified studies and extracted data. Risk ratios (RRs) were pooled across studies using random-effects models.

RESULTS

Nine studies were included (five RCTs, three retrospective cohort studies and one prospective cohort study). In comparison to P-S, treatment with P-C or TMP-SMX was associated with similar rates of partial or complete clinical response [P-C: RR 0.87; 95% confidence interval (CI) 0.70-1.08; TMP-SMX: RR 0.97; 95% CI 0.78-1.21], radiological response (P-C: RR 0.92; 95% CI 0.82-1.03), skin rash (P-C: RR 0.81; 95% CI 0.56-1.17; TMP-SMX: RR 0.17; 95% CI 0.02-1.29), gastrointestinal impairment (P-C: RR 5.16; 95% CI 0.66-40.11), and drug discontinuation because of adverse events (P-C: RR 0.32; 95% CI 0.07-1.47). Liver impairment was more frequent with P-S than P-C (P-C vs. P-S: RR 0.48; 95% CI 0.24-0.97).

CONCLUSIONS

The current evidence fails to identify a superior regimen in terms of relative efficacy or safety for the treatment of HIV-associated cerebral toxoplasmosis. Use of TMP-SMX as preferred treatment may be consistent with the available evidence and other real-world considerations. Larger comparative studies are needed.

ID: 100: A SYSTEMATIC REVIEW AND META-ANALYSIS OF THE RELATIVE EFFICACY AND SAFETY OF TREATMENT REGIMENS FOR HIV-ASSOCIATED CEREBRAL TOXOPLASMOSIS

Aim

The objective of this study was to perform a systematic review and meta-analysis of the literature to evaluate efficacy and safety of therapies for cerebral toxoplasmosis in HIV-infected adults. Pyrimethamine plus sulfadiazine (P-S) combination is considered the mainstay therapy for cerebral toxoplasmosis and pyrimethamine plus clindamycin (P-C) is the most common alternative treatment. Although, trimethoprim-sulfamethoxazole (TMP-SMX) has potential advantages, its use is infrequent.

Methods

Design: Systematic review and meta-analysis. We searched PubMed and 4 other databases to identify randomized controlled trials (RCTs) and cohort studies. Two independent reviewers searched and identified studies and extracted data. Risk ratios (RRs) were pooled across studies using random-effects models.

Results

Nine studies were included (5 RCTs, 3 retrospective cohorts, 1 prospective cohort). In comparison to P-S, treatment with P-C or TMP-SMX had similar partial or complete clinical response (P-C: RR 0.87, 95%CI 0.70–1.08; TMP-SMX: RR 0.97, 95%CI 0.78–1.21), radiological response (P-C: RR 0.92, 95%CI 0.82–1.03), skin rash (P-C: RR 0.81, 95%CI 0.56–1.17; TMP-SMX: RR 0.17, 95%CI 0.02–1.29), gastrointestinal impairment (P-C: RR 5.16, 95%CI 0.66–40.11), and drug discontinuation due to adverse events (P-C: RR 0.32, 95%CI 0.07–1.47). Liver impairment was more frequent with P-S than P-C (P-C vs P-S: RR 0.48, 95% CI 0.24–0.97).

Conclusions

The current evidence fails to identify one superior regimen in terms of relative efficacy or safety for the treatment of HIV-associated cerebral toxoplasmosis. Use of TMP-SMX as preferred treatment may be consistent with the available evidence and other real world considerations. Larger comparative studies are needed.

ID: 24: BENEFITS AND RISKS OF WARFARIN WITH AND WITHOUT ASPIRIN IN PATIENTS WITH CORONARY ARTERY DISEASE OR CEREBROVASCULAR ACCIDENT: A META-ANALYSIS OF RANDOMIZED CONTROLLED TRIALS

Background

Previous studies have shown that secondary prophylaxis of non-embolic stroke remains challenging. Randomized controlled trials (RCTs) evaluating warfarin with or without aspirin to prevent stroke have yielded mixed results. We conducted a meta-analysis of RCTs to evaluate the efficacy of warfarin (with and without aspirin) in patients with coronary artery disease (CAD) or ischemic stroke/ transient ischemic attack (TIA).

Methods

We searched 6 electronic databases published from 1980–2014. RCTs reporting the benefits (reduced incidence of stroke) and risks (mortality, intracranial bleeds, major and minor bleeds) of warfarin (with and without aspirin) therapy were included. Trials were stratified by intensity of the therapeutic international normalized ratio (INR): low (INR<2), intermediate (INR 2–3) and high (INR>3). Risk ratios (RRs) were pooled using random-effects models.

Results

Twenty-five RCTs (30,939 patients) met our inclusion criteria. Intermediate intensity warfarin with aspirin compared with aspirin alone significantly reduced the risk of secondary strokes [RR 0.48, 95% confidence interval (CI) 0.29–0.80], but increased the risk of major bleeding (RR 2.54, CI 1.70–3.79); there were no significant differences in mortality (RR 1.00, CI 0.80–1.25) and intracranial bleeding (RR 3.03, CI 0.48–19.20). Intermediate intensity warfarin without aspirin compared with aspirin alone, significantly increased major bleeding (RR 2.11, CI 1.45–3.06); there were no significant differences for stroke (RR 0.84, CI 0.66–1.08), mortality (RR1.21, CI 0.90–1.63) and intracranial bleeding (RR 1.87, CI 0.94–3.70).

Conclusions

Use of intermediate intensity warfarin with aspirin reduced the risk of stroke at the price of increased bleeding. Most anticoagulation increased the risk of major bleeding with no effect on mortality. Studies with oral anticoagulants with aspirin for secondary prevention should be considered.

ID: 43: INSULIN RESISTANCE AND ENDOMETRIAL CANCER RISK: A SYSTEMATIC REVIEW AND META-ANALYSIS

Aim

It has been suggested that chronic hyperinsulinemia from insulin resistance is involved in the etiology of endometrial cancer (EC). We performed a systematic review and meta-analysis to assess whether insulin resistance is associated with the risk of EC.

Methods

We searched PubMed-Medline, Embase, Scopus, and Web of Science for articles published from database inception through 30th September 2014. We included all observational studies evaluating components defining insulin resistance in women with and without EC. Quality of the included studies was assessed by Newcastle-Ottawa scale. Random effects models and inverse variance method were used to meta-analyze the association between insulin resistance components and EC.

Results

Twenty-five studies satisfied our inclusion criteria. Fasting insulin levels (13 studies, n=4088) were higher in women with EC (mean difference [MD] 33.94 pmol/L, 95% confidence interval [CI] 15.04–52.85, p=0.0004). No differences were seen in postmenopausal versus pre- and postmenopausal subgroup analysis. Similarly, non-fasting/fasting C-peptide levels (five studies, n=1938) were also higher in women with EC (MD 0.14 nmol/L, 95% CI 0.08–0.21, p<0.00001). Homeostatic model assessment – insulin resistance (HOMA-IR) values (six studies, n=1859) in EC patients were significantly higher than in women without EC (MD 1.13, 95% CI 0.20–2.06, p=0.02). There was moderate-to-high heterogeneity among the included studies.

Conclusion

Currently available epidemiologic evidence is suggestive of significantly higher risk of EC in women with high fasting insulin, non-fasting/fasting C-peptide and HOMA-IR values.

Meta-analysis of the association between obstructive sleep apnoea and postoperative outcome

BACKGROUND

Obstructive sleep apnoea (OSA) is often undiagnosed before elective surgery and may predispose patients to perioperative complications.

METHODS

A literature search of PubMed-Medline, Web of Science, Scopus, EMBASE, Cochrane Database of Systematic Reviews, and Cochrane Central Register of Controlled Trials up to November 2010 was conducted. Our search was restricted to cohort or case-control studies in adults diagnosed with OSA by screening questionnaire, oximetry, or polysomnography. Studies without controls, involving upper airway surgery, and with OSA diagnosed by ICD-9 codes alone were excluded. The primary postoperative outcomes were desaturation, acute respiratory failure (ARF), reintubation, myocardial infarction/ischaemia, arrhythmias, cardiac arrest, intensive care unit (ICU) transfer, and length of stay.

RESULTS

Thirteen studies were included in the final analysis (n=3942). OSA was associated with significantly higher odds of any postoperative cardiac events [45/1195 (3.76%) vs 24/1420 (1.69%); odds ratio (OR) 2.07; 95% confidence interval (CI) 1.23-3.50, P=0.007] and ARF [33/1680 (1.96%) vs 24/3421 (0.70%); OR 2.43, 95% CI 1.34-4.39, P=0.003]. Effects were not heterogeneous for these outcomes (I(2)=0-15%, P>0.3). OSA was also significantly associated with higher odds of desaturation [189/1764 (10.71%) vs 105/1881 (5.58%); OR 2.27, 95% CI 1.20-4.26, P=0.01] and ICU transfer [105/2062 (5.09%) vs 58/3681 (1.57%), respectively; OR 2.81, 95% CI 1.46-5.43, P=0.002]. Both outcomes showed a significant degree of heterogeneity of the effect among studies (I(2)=57-68%, P<0.02). Subgroup analyses had similar conclusions as main analyses.

CONCLUSIONS

The incidence of postoperative desaturation, respiratory failure, postoperative cardiac events, and ICU transfers was higher in patients with OSA.

Reverse transcriptase PCR quantitation of hepatitis C virus

OBJECTIVE

To present a brief review of the diagnostic benefits of quantitating viral load for hepatitis C and how the reverse transcriptase polymerase chain reaction is being used as an aid to better diagnose and manage the disease.

DATA SOURCE

Research articles about hepatitis C and the reverse transcriptase polymerase chain reaction, as well as data gathered by the authors.

STUDY SELECTION

Performed by the authors.

DATA EXTRACTION

Performed by the authors.

DATA SYNTHESIS

Hepatitis C viral infection is a worldwide health problem, affecting about 100 million people worldwide. Numerous serological tests exist to detect antibodies to hepatitis C antigens, but some affected people fail to generate an immune response. Reactivity in the reverse transcriptase polymerase chain reaction is definitive proof of hepatitis C infection. The titer of RNA indicates patient response to antiviral therapy. Measuring the presence and quantity of RNA by the reverse transcriptase polymerase chain reaction has become an important aid for diagnosis and monitoring of hepatitis C infection.

CONCLUSION

The reverse transcriptase polymerase chain reaction method is a highly sensitive and accurate aid in diagnosing or confirming diagnosis of hepatitis C viral infection. This method is widely used to assess likelihood of patient response to therapy, and to monitor efficacy during therapy.

Tumor necrosis factor and interleukin-1 stimulate testosterone secretion in adult male rat Leydig cells in vitro

The actions of two cytokines, tumor necrosis factor (TNF) and interleukin-1 (IL-1), on testosterone production by dispersed adult testis cells and purified Leydig cells in culture were studied. In one set of experiments, testis cells from adult (90-day-old) rats were enzymatically dispersed. In another set of experiments, the dispersed testis cells were placed on a Percoll density gradient and were centrifuged to yield purified (greater than 85%) Leydig cells. Both whole testis cells and purified Leydig cells were cultured in the presence of varying doses of TNF or IL-1 with or without maximally stimulating doses of human chorionic gonadotropin (hCG). Both TNF and IL-1 stimulated basal secretion of testosterone in whole testis cells, as well as purified Leydig cells. Additionally, both TNF and IL-1 augmented maximally hCG stimulated testosterone secretion. Both cytokines stimulated testosterone secretion by dispersed testis cells as early as 4 hours, and the effect continued for up to 72 hours. The cytokines slightly, but significantly, stimulated testosterone production in purified Leydig cells after 24 hours, and continued for up to 72 hours. We have concluded from this data that TNF and IL-1 stimulate the testosterone secretion by adult rat Leydig cells. While this effect might be mediated through the action of the cytokines on testicular macrophages, there might also be a direct effect on the Leydig cell since augmentation of secretion occurred in purified Leydig cells, as well as whole testis cells. Therefore, TNF and IL-1 may serve as local regulators of Leydig cell function.

Metabolism of 5 alpha reduced androgens by various tissues of the male rat

Since an animal model for the study of peripheral androgen metabolism is needed, we studied the metabolism of 5 alpha-reduced androgens in various tissues of the rat. Labeled DHT and 3 alpha androstanediol (3 alpha diol) were added to tissue minces of male rat scrotal skin, muscle, prostate, or liver. Conversion ratios of the interconverting pair DHT in equilibrium with 3 alpha diol or the formation of the respective glucuronides (G) were determined over a 3 h period. Major differences in the activity and the oxidation/reduction relationship were observed between tissues. Scrotal skin was very active and balanced in the DHT in equilibrium with 3 alpha diol interconversion (31 and 33%/100 mg/3 h, respectively, whereas liver was minimally active (3.1/2.7%). 3 alpha reduction was prominent in muscle (37.0/2.7%), although 3 alpha oxidation was more active in prostate (6.0/31.5%). Steroid glucuronidation also differed in the various tissues. Sexual skin formed about 2% 3 alpha diol G, but much smaller amounts of DHTG. Liver, muscle, and prostate formed minimal (less than 0.2%) 3 alpha diol G, although liver synthesized 1.2% of DHTG. Addition of DHT or 3 alpha diol increased formation of the respective glucuronides by liver, whereas DHT blocked the synthesis of 3 alpha diol G, and 3 alpha diol markedly increased formation of 3 alpha diol G in skin. These studies indicate a similarity in DHT metabolism between rat and human sexual skin and a high rate of glucuronidation compared with other tissues. The pathway of 3 alpha diol G formation in skin is DHT----3 alpha diol----3 alpha diol G. Steroid 3 alpha oxidase is more active than 3 alpha reductase in muscle whereas 3 alpha oxidase predominates in prostate. This may be a mechanism whereby DHT levels and action as a nuclear androgen is favored in prostate, whereas testosterone is the major androgen in muscle.(ABSTRACT TRUNCATED AT 250 WORDS)

Conversion of dihydrotestosterone to androstanediol glucuronide by female sexual skin

Sexual skin biopsies from 13 normal women were obtained and minces/3-h studied after adding either [3H]dihydrotestosterone (DHT) or [3H]androstanediol (3 alpha diol) to RPMI-1640 medium in a Dubnoff apparatus. Unconjugated or conjugated androgens (after hydrolysis) were purified by three chromatography steps. Formation of 3 alpha diol and 3 alpha diol glucuronide (3 alpha diolG) was linear with time. The conversion of DHT to DHT17 beta G was only 4.4 +/- 0.5%/200 mg/3 h, while conversion to 3 alpha diol was 32 +/- 1.7%. The back conversion of 3 alpha diol to DHT was 30 +/- 3% and conversion to 3 alpha diolG was 4.5 +/- 1.25%. The product of the conversion separately measured of DHT to 3 alpha diol and 3 alpha diol to 3 alpha diolG was 1.5%, which is not very different than the overall conversion rate of DHT to 3 alpha diolG of 1.4%. This study indicates that the predominant path in this tissue is DHT in equilibrium 3 alpha diol----3 alpha diolG, rather than formation of DHT17 beta G and then 3 alpha reduction to 3 alpha diolG.