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PubMedDate not supplied

Pharmacokinetics of methyl parathion: a comparison following single intravenous, oral or dermal administration.

Assessment of the risks posed by the residential use of methyl parathion requires an understanding of its pharmacokinetics after different routes of exposure. Thus, studies were performed using adult female rats to define the pharmacokinetic parameters for methyl parathion after intravenous injection and to apply the described model to an examination of its pharmacokinetics after single oral or dermal exposure. The pharmacokinetics of methyl parathion after intravenous administration (1.5 mg/kg) were best described by a three-compartment model; the apparent volume of the central compartment was 1.45 liters/kg, clearance was 1.85 liters/h/kg and the terminal half-life was 6.6 h with an elimination constant of 0.50 h(-1). The apparent oral absorption coefficient for methyl parathion (1.5 mg/kg) was 1.24 h(-1), and its oral bioavailability was approximately 20%. The latter likely includes a significant first pass effect. Concentrations of methyl parathion increased during the initial 10-60 min and then declined during the next 15-36 h. After dermal administration (6.25-25 mg/kg), methyl parathion concentrations peaked within 12-26 h and then declined dose dependently. The apparent dermal absorption coefficient was approximately 0.41 h(-1), and only two pharmacokinetic compartments could be distinguished. In conclusion, the pharmacokinetics of methyl parathion are complex and route dependent. Also, dermal exposure, because of sustained methyl parathion concentrations, may pose the greatest risk.

Administration, Cutaneous↗
PubMed1996

In vivo microautoradiography of [3H]1,24(OH)2D3 (tacalcitol) following topical application to normal rats and in vitro metabolism in human keratinocytes.

This study was conducted to investigate the mechanism of topical absorption of [3H]1,24(OH)2D3 (1,24-dihydroxyvitamin D3; tacalcitol) by applying an ointment containing 4 micrograms2/g [3H]1,24(OH)2D3 to the skin of rats using an occlusion method. Microautoradiography of the skin at the application site 1 h after topical treatment showed a high concentration of radiolabel in the stratum corneum, the epidermis and around the hair follicles. Radiolabel was also seen in the epidermis and hair follicle areas 8 h and 24 h after application. The radiolabel was distributed to a minor extent to the subcutaneous fat layer. Microautoradiography showed two routes of purcutaneous absorption of 1,24(OH)2D3: through the stratum corneum and epidermis into the microvessels, and through hair follicle areas into the bloodstream. After topical application of an ointment containing 4 micrograms/g or 40 micrograms/g [3H]1,24(OH)2D3 to the shaved neck skin of rats, the absorption rate, estimated by excretion in the urine and faeces, was about 30% of the total applied radioactivity. The main excretion route after topical application was in the faeces. Furthermore, 1,24(OH)2D3 added to human adult keratinocytes was not metabolized into other compounds, and only the unchanged compound was detected. These findings strongly suggest that 1,24(OH)2D3 distributed into the epidermis acts on epidermal keratinocytes. Topical application of 1,24(OH)2D3 appears to be a possible approach to the treatment of psoriasis and other skin diseases through its action on the 1,25(OH)2D3 receptor, which reportedly plays a very important role in the regulation of proliferation and differentiation of keratinocytes.

Absorption↗
PubMedDate not supplied

Pulsed estrogen therapy: pharmacokinetics of intranasal 17-beta-estradiol (S21400) in postmenopausal women and comparison with oral and transdermal formulations.

Pharmacokinetics of estradiol and estrone were assessed in postmenopausal women receiving S21400, a novel 17beta-estradiol formulation administered by nasal route; the results were compared with those obtained with oral and transdermal routes. Thirty six women received three treatments: a specified dose of 17beta-estradiol (100, 300 or 450 microg) given once and as 2 doses, 12 h apart, using three parallel dose groups in a randomised, crossover study. Thereafter, a reservoir patch (50 microg/day of 17beta-estradiol) or a tablet of 2 mg micronised 17beta-estradiol were randomly administered. Plasma concentrations of estradiol and estrone were measured by radioimmunoassays. Following intranasal dosing, estradiol was rapidly absorbed with plasma concentrations reaching maximal values (approximately 1400 pg/ml with a single 300 microg dose) after 10-30 min and returning within 12 h to levels of untreated postmenopausal women. Systemic exposure to estradiol was dose proportional and independent of the treatment regimen. Moreover, the dose of 300 microg gave an estimated 24 h systemic exposure to exogenous estradiol close to that of the 50 microg/day reservoir patch or the 2 mg tablet. The mean estrone to estradiol ratio was similar and 4-fold lower than those with the patch and the tablet, respectively. In conclusion, by this new route for estrogen replacement therapy, the nasal route, the pharmacokinetics of estradiol as S21400 were linear and displayed a 'pulsed' kinetic profile, different from those obtained with the usual routes of administration.

Administration, Cutaneous↗
PubMedDate not supplied

Recent developments in topical and transdermal delivery.

Over the past decade there has been considerable interest shown in an understanding of the mechanisms of skin penetration and its enhancement. Sophisticated biophysical techniques have been used to probe, at a molecular level, the ways in which chemical and physical enhancement can be achieved. Two types of chemical penetration enhancers can be identified and their co-administration can result in synergistic effects. Another attractive method for enhancing skin penetration is the use of supersaturation but problems associated with stability must be addressed. Biotech drugs are inherently difficult to administer and recent progress using iontophoresis and sonophoresis has identified that medicines of this type can be delivered percutaneously. It is also possible to use the percutaneous route to monitor plasma levels non-invasively. Coupling non invasive monitoring with controlled delivery allows the possibility of creating transdermal systems which act with bio feedback.

Administration, Cutaneous↗
PubMedDate not supplied

Transdermal 17 beta-estradiol combined with oral progestogen increases plasma levels of insulin-like growth factor-I in postmenopausal women.

In order to evaluate the effect of postmenopausal estrogen replacement therapy on the plasma levels of the insulin-like growth factor-I (IGF-I) 12 postmenopausal women aged 44 to 59 years were studied. The control group consisted of 15 healthy premenopausal women aged 20-44 years. In the postmenopausal women the plasma levels of IGF-I, gonadotrophins and sex hormones were determined before and after 3 and 6 months cyclic replacement therapy with transdermal 17 beta-estradiol (E2 100 micrograms patches applied twice weekly) combined with oral chlormadinone acetate (2 mg daily for 7 days in each cycle). Basal levels of estradiol (E2), IGF-I, dehydroepiandrosterone sulphate (DHEA-S), testosterone and androstenedione were lower, but gonadotropin levels were higher in postmenopausal than in premenopausal women. In all the women studied age was inversely correlated with IGF-I levels (r = -0.793, p less than 0.001) and with DHEA-S concentrations (r = -0.435, p less than 0.02). In postmenopausal women transdermal estradiol administration restored the circulating E2 levels to the early follicular range and increased the IGF-I levels (from 76.4 +/- 9.2 micrograms/l to 141.8 +/- 20.8 micrograms/l; p less than 0.01). Transdermal estradiol decreased gonadotrophin levels without changes in concentration of DHEA-S, testosterone, androstenedione and SHBG. In postmenopausal women before and during replacement therapy a positive correlation was found between estradiol and IGF-I concentrations (r = -0.439, p less than 0.01). These results suggest that cyclic replacement therapy with transdermal 17 beta-estradiol in combination with chlormadinone acetate given orally increase the plasma levels of IGF-I in postmenopausal women.

Administration, Cutaneous↗
PubMed2002

Effects of sequential combined transdermal and oral hormone replacement therapies on serum lipid and lipoproteins in postmenopausal women.

The aim of this study was to compare the effects of sequential combined transdermal and oral postmenopausal hormone replacement therapies on serum lipid-lipoprotein profiles risk markers for cardiovascular disease. A prospective randomize study was designed: Ninety-six healthy nonhysterectomised postmenopausal women were randomized to receive either transdermal continuous 17beta-estradiol, 0.05 mg/d (Estraderm TTS, Novartis, Basel, Switzerland), with transdermal sequential norethisterone acetate, 0.25 mg/d (Estragest TTS, Novartis, Basel, Switzerland), or oral continuous conjugated equine estrogens, 0.625 mg/d (Premarin 0.625 mg, Wyeth, Philadelphia, U.S.A.), with oral sequential medroxyprogesterone acetate, 10 mg/d (Farlutal 5 mg, Deva, Istanbul, Turkey). 84 women completed the trial, 42 in oral and 42 in the transdermal group. The serum levels of total cholesterol, LDL-cholesterol, HDL-cholesterol, triglycerides, apolipoproteins AI and apolipoproteins B at 6 months after starting treatment were compared with baseline values for both therapies. Both oral and transdermal therapies significantly reduced serum levels of total cholesterol (208-190 mg/dL and 216-199 mg/dL, respectively, p=0.0001) and LDL-cholesterol (128-112 mg/dL and 140-127 mg/dL, respectively, p=0.001). The serum levels of triglycerides did not show any significant change with oral therapy, whereas this lipid fell (128-101 mg/dL, p=0.0001) significantly with transdermal therapy. We found significant decrease in HDL-cholesterol with transdermal therapy while there was no significant change with oral therapy. Apolipoproteins AI, the major protein component of HDL2 subfraction, was increased by oral therapy and lowered by transdermal therapy. As a conclusion, we have found that serum total cholesterol and LDL-cholesterol were lowered by both therapies, with no significant differences between treatments, whereas there were significant differences between treatments according to effects on serum triglycerides and apolipoproteins AI.

Administration, Cutaneous↗
PubMed2006

Transdermal application of lovastatin to rats causes profound increases in bone formation and plasma concentrations.

INTRODUCTION: Statins are drugs that inhibit HMG Co-A reductase and have been shown to enhance bone formation in vitro and in vivo in rodents. However, the statins currently used for cholesterol-lowering have been selected for their capacity to target the liver where their effects on cholesterol synthesis are mediated and they undergo first pass metabolism. When given in lipid-lowering doses, these agents do not likely reach sufficient blood concentrations to reliably cause substantial increases in bone formation in humans. Moreover, statins are inactivated by cytochrome P450 enzymes, resulting in even less peripheral distribution of the biologically active moieties beyond the liver. METHOD: To investigate whether an alternate method of administration might produce beneficial effects on bone formation, we administered lovastatin by dermal application to rats to circumvent the first-pass effects of the gut wall and liver. RESULTS: We found that the statin blood levels measured by HMG Co-A reductase activity were higher, maintained longer and less variable following transdermal application than those following oral administration. Also the increased circulating statin levels were associated with significantly enhanced biological effects on bone. After only 5 days of administration of transdermal lovastatin to rats, there was a 30-60% increase in trabecular bone volume, and 4 weeks later, we observed more than a 150% increase in bone formation rates. There was also a significant increase in serum osteocalcin, a marker of bone formation. We also found that lovastatin administered transdermally produces these profound effects at doses in the range of 1% of the oral dose, without any evidence of the hepatotoxicity or myotoxicity that can occur following oral statin administration. Several doses (0.01-5 mg kg(-1) day(-1)) and dosage schedules were examined, and collectively the data strongly suggest a powerful anabolic effect but with an unusually flat dose-response curve. CONCLUSION: These results show transdermal application of statins produces greater beneficial effects on bone formation than oral administration does.

Administration, Cutaneous↗
PubMed2003

Dermal and inhalation acute toxic class methods: test procedures and biometric evaluations for the Globally Harmonized Classification System.

The acute toxic class (ATC) methods were developed for determining LD(50)/LC(50) estimates of chemical substances with significantly fewer animals than needed when applying conventional LD(50)/LC(50) tests. The ATC methods are sequential stepwise procedures with fixed starting doses/concentrations and a maximum of six animals used per dose/concentration. The numbers of dead/moribund animals determine whether further testing is necessary or whether the test is terminated. In recent years we have developed classification procedures for the oral, dermal and inhalation routes of administration by using biometric methods. The biometric approach assumes a probit model for the mortality probability of a single animal and assigns the chemical to that toxicity class for which the best concordance is achieved between the statistically expected and the observed numbers of dead/moribund animals at the various steps of the test procedure. In previous publications we have demonstrated the validity of the biometric ATC methods on the basis of data obtained for the oral ATC method in two-animal ring studies with 15 participants from six countries. Although the test procedures and biometric evaluations for the dermal and inhalation ATC methods have already been published, there was a need for an adaptation of the classification schemes to the starting doses/concentrations of the Globally Harmonized Classification System (GHS) recently adopted by the Organization for Economic Co-operation and Development (OECD). Here we present the biometric evaluation of the dermal and inhalation ATC methods for the starting doses/concentrations of the GHS and of some other international classification systems still in use. We have developed new test procedures and decision rules for the dermal and inhalation ATC methods, which require significantly fewer animals to provide predictions of toxicity classes, that are equally good or even better than those achieved by using the conventional LD(50)/LC(50) methods. In order to cope with rather narrow dose/concentration classes of the GHS we have, as in our previous publications, combined the outcome of all results that can be obtained during testing for the allocation to one of the defined toxicity classes of the GHS. Our results strongly recommend the deletion of the dermal LD(50) and the inhalation LC(50) test as regulatory tests and the adoption of the dermal and inhalation ATC methods as internationally accepted alternatives.

Administration, Cutaneous↗
PubMed2001

Does the polymorphism of cytochrome P-450 2E1 affect the metabolism of N,N-dimethylformamide? Comparison of the half-lives of urinary N-methylformamide.

The aim of this study was to clarify whether phenotypic variation exists when subjects with different genotypes of cytochrome P450 2E1 (CYP2E1) are exposed to N,N-dimethylformamide (DMF). The genotypes of CYP2E1 were confirmed in 123 healthy male volunteer subjects. Of the 123 subjects, the numbers of c1 homozygotes, c2 heterozygotes, and c2 homozygotes were 77, 45, and 1, respectively. Seven of the c1 homozygotes, five of the c2 heterozygotes, and the one c2 homozygote (mean age: 22.7 years, range: 20-27 years) were exposed to DMF vapor twice, once via the skin and once via the lung, for a total of 8 h per subject at a concentration below 10 ppm, the occupational exposure limit recommended by the Japan Society for Occupational Health, the American Conference of Governmental and Industrial Hygienists, and Deutsche Forschungsgemeinschaft, at 27 degrees C and 44% relative humidity. Exposure levels were 6.2+/-1.0 ppm in dermal exposure and 7.1+/-1.0 ppm in inhalation exposure. Urine samples were collected until 72 h after exposure. The half-lives of urinary N-methylformamide (NMF) were obtained as the phenotype. The average urinary NMF half-lives of the c1 homozygotes, the c2 heterozygotes, and the c2 homozygote were 3.86+/-1.90, 4.38+/-1.53, and 4.2 h after dermal exposure, and 1.58+/-0.42, 1.84+/-0.61, and 3.2 h after respiratory exposure. The NMF half-lives of the c1 homozygotes were not significantly different from those of the c2 heterozygotes, and there were no differences between the NMF half-lives on the subjects with and without the c2 allele. Even though the data were obtained from only one c2 homozygote, it is noteworthy that the NMF half-life of this subject was slightly less than that of the c1 homozygotes after respiratory exposure.

Administration, Cutaneous↗
PubMed2000

An intra-laboratory validation of the Integrated Model for the Differentiation of Skin Reactions (IMDS): discrimination between (photo)allergic and (photo)irritant skin reactions in mice.

We recently presented a modified local lymph node test which made it possible to quickly and reliably differentiate between irritative and allergic skin reactions with extremely simple parameters. The Integrated Model for the Differentiation of Skin Reactions (IMDS) test combines measurement of cell proliferation in draining lymph nodes with measurement of primary ear swelling after topical application of the test substance on three consecutive days. In contrast to the 'classic' skin sensitisation test in guinea-pigs the IMDS test is considerably faster and is based on objective measured data, not subjective skin evaluations. Like the Local Lymph Node Assay (LLNA), measurement of allergic potential in the IMDS test is based on the underlying immunological mechanisms, but also considers the behaviour of immune competent cells following non-specific activation by irritants. In addition, the IMDS test can employ UV radiation after application of the substance and, therefore, make differentiation possible between different types of skin photoreaction (photoallergy and photoirritation) after both topical and systemic administration. Attempts to achieve this kind of discrimination with the LLNA necessitate considerably greater expenditure, as proliferation in the draining lymph nodes can also be induced by moderate to extreme (photo)irritants. In a previous paper in which we presented the IMDS test, we examined each type of reaction in reference to one single standard; the next logical step was therefore a broad-based intra-laboratory validation. An important factor in the validation was the use of standards that had been thoroughly examined in both guinea pig and mouse systems and were also relevant with regard to estimation of the risk for humans. The data presented here show that the IMDS is a simple and reliable tool for obtaining fast and reproducible assessments of potential (photo)allergic and (photo)irritant skin reactions to substances.

Administration, Cutaneous↗
PubMed2005

Medication screening for smoking cessation: a proposal for new methodologies.

RATIONALE: The purpose of medication screening studies is to quickly and cheaply evaluate the clinical potential of medications, so that promising drugs proceed to large-scale clinical trials and unpromising drugs do not. Screening procedures for smoking cessation medications either are not sufficiently practical or lack clinical validity. Clinical trials have clinical validity but are often impractical as initial tests of efficacy (i.e., screening) or suffer from limited statistical power. The alternative approach of short-term, laboratory-based studies of purported mechanisms of efficacy may overcome some of the practical problems of clinical trials but appear to have limited clinical validity. OBJECTIVES: This commentary identifies some of the limitations of current short-term screening procedures and provides suggestions for improving such studies. RESULTS: Short-term screening studies typically use smokers unmotivated to abstain (i.e., nontreatment seekers) as participants and examine brief medication effects on clinical markers or potential mechanisms of action, including relief of withdrawal and craving during enforced abstinence or on reduction in the reinforcing effects of smoked tobacco. The limitation of these approaches is shown by their insensitivity to effects of nicotine replacement and bupropion, which are effective in clinical trials for smoking cessation. CONCLUSIONS: The clinical validity of short-term screening studies may improve if these studies simulate some clinical trial procedures within practical limitations. Thus, they should recruit smokers motivated to abstain, emphasize smoking abstinence as a primary index of medication response, examine effects over sufficiently long time periods to encompass the drug's mechanism of action, and assess responses in the natural environment. Whether these changes improve the sensitivity of screening studies is testable. Other research aimed specifically at identifying the mechanisms of therapeutic action of a medication may also profit from using this approach of simulating a short-term clinical trial.

Administration, Cutaneous↗
PubMed2006

Preferences among four combination nicotine treatments.

RATIONALE: Acute nicotine replacement treatments (NRTs) are disliked or misused, leading to insufficient nicotine intake and poor outcome. Patches provide steady nicotine but are slow and passive. Combining systems may improve efficacy with acute NRTs tailored for compliance. OBJECTIVE: To test initial reactions to and use preferences among combinations of NRTs. MATERIALS AND METHODS: Smokers (n=27) tested four combination NRTs in a 5-day crossover trial: 2/4-mg gum + 15-mg patch (G/P), 2/4-mg lozenges + 15-mg patch (L/P), inhaler + 15-mg patch (I/P), and 10 mg + 15-mg patches (P/P). Subjects rated an NRT combination each day after 5-6 h of use and ranked among the NRTs after testing all treatments. RESULTS: Double-patches (P/P) were ranked highest for "ease of use", "safety", and "use in public". However, for "help to quit", 70% preferred some form of acute-patch combination (A/P) compared to 30% choosing P/P. For "use under stress" (an immediate need), 93% preferred A/P systems compared to 7% choosing P/P. L/P ranked lowest for "ease of use", I/P and L/P were lowest on "safety", and I/P ranked lowest for "use in public". Expectations of NRTs changed with test experience for patches (better) and lozenges (worse). CONCLUSIONS: In brief testing, all combinations were acceptable. P/P was favored for ease, safety, and public use, but a majority chose A/P systems for help in quitting and use under stress. Combined use is viable and needs to be made known and accessible to smokers.

Administration, Cutaneous↗
PubMed2001

Individual differences in preferences for and responses to four nicotine replacement products.

RATIONALE: With several different forms of nicotine replacement therapy available for smokers, it is useful to know about factors that may influence choice of form. OBJECTIVE: To examine factors associated with preference for different nicotine replacement products and effectiveness of these products. The simple comparison of success rates between the products has been reported previously. METHODS: Five hundred and four smokers were invited to rank order four products (gum, patch, nasal spray and inhaler) in terms of preference and were then randomly allocated to receive one of the products for a smoking cessation attempt. They were followed up 1 week, 4 weeks, 12 weeks and 15 weeks later. Ratings of the products were repeated 1 week after the quit date. Mood and physical symptoms were assessed at baseline and at each follow-up visit. Urges to smoke were assessed at all post-quit date sessions. Abstinence was assessed by self-report with expired air carbon monoxide verification. RESULTS: The patch was the most popular product initially, followed by the spray and inhaler and then the gum. The difference was greater for women than men. However, all smokers quickly came to like whichever product they had been allocated. Smokers who initially preferred the spray or inhaler were heavier smokers than those who preferred the gum or patch. Prior experience of the gum was associated with lower initial preference for it, but did not affect outcome. Prior experience with the patch had no effect on preference or outcome. Being allocated to the preferred product did not increase success at stopping smoking. Women were more successful at stopping smoking on the inhaler than the gum. Among highly dependent smokers, those on the inhaler had a lower relapse rate than those on the other products. CONCLUSIONS: Regardless of initial preferences, whether patients obtain their preferred form of NRT or one selected for them did not seem to affect outcome. This may be because smokers came to like particular products as they got used to them. Other things being equal, women may be better advised to use inhaler rather than gum and men vice versa.

Administration, Cutaneous↗
PubMed2004

Diclofenac systemic exposure is not increased when topical diclofenac is applied to ultraviolet-induced erythema.

OBJECTIVES: Diclofenac is a non-steroidal anti-inflammatory drug used for a variety of painful and inflammatory conditions. A new low-dose, topical-gel form of diclofenac sodium (diclofenac-Na) has been developed for pain relief and redness reduction after sunburn. The objective was to compare exposure to oral diclofenac-Na with the systemic exposure to diclofenac after application of the new topical diclofenac-Na 0.1% Emulgel gel (diclofenac-Na gel) to normal skin and to that with ultraviolet-induced erythema relative. METHODS: This study was an open, single-centre, three-period, non-randomised trial in 18 healthy Caucasian subjects. During the first period, 12.5 g gel (12.5 mg diclofenac-Na) was applied twice on a single day to normal skin. During the second period, a 25-mg diclofenac-Na, enteric-coated tablet was given orally three times in a single day. During the third period, the diclofenac-Na gel was applied, as in the first period, but during the early phase of an erythema induced by three times the ultraviolet minimal erythema dose, i.e. a first-degree sunburn associated with pain. During each period, venous blood samples were collected over 24 h and urine was collected over 72 h after first administration for the determination of diclofenac in plasma and urine and of 4'-OH-diclofenac in urine. RESULTS: The systemic exposure after topical application of 25 mg diclofenac-Na on sunburned skin was less than 3% that of 75 mg oral diclofenac-Na and was not increased to that measured on normal skin. CONCLUSION: The diclofenac-Na 0.1% Emulgel gel can be applied safely to sunburned skin (superficial sunburn, i.e. first degree) as well as to normal skin.

Administration, Cutaneous↗
PubMed1998

Lipid effects of an intrauterine levonorgestrel device or oral vs. vaginal natural progesterone in post-menopausal women treated with percutaneous estradiol.

BACKGROUND: The ideal progestin for combined hormone replacement therapy should be free of adverse effects on lipid metabolism. We therefore examined lipid profiles during continuous hormone replacement therapy (HRT) with an estradiol-gel combined with either a levonorgestrel-releasing intrauterine device (LNG-IUD) or oral/vaginal natural progesterone. METHODS: Sixty menopausal women recruited in this open, non-randomised parallel three-group study received percutaneous gel containing 1.5 mg of estradiol daily. Progestin was administered to the women with an LNG-IUD (n = 20), as oral natural progesterone (n = 21) 100 mg daily on the 1-25 calendar days of the month or as vaginal progesterone (n = 19) 100-200 mg daily on the 1-25 calendar days of the month. Serum concentrations for total cholesterol, LDL-cholesterol, HDL-cholesterol, triglycerides and sex hormone binding globulin (SHBG) were measured at 0, 6 and 12 months. The median (and 95% confidence interval) of the serum SHBG, total, LDL-, HDL- cholesterol and triglycerides concentrations at baseline and after 6 and 12 months of the study and the ratio of 6 and 12 months values to baseline values were calculated. RESULTS: Total cholesterol was significantly decreased (8%) in the vaginal progesterone group at the end of the trial. HDL-cholesterol did not change in either of the progesterone groups, while a slight but transient decrease (median 15%) was seen at 6 months in the LNG-IUD group. There were no significant changes in triglycerides or LDL-cholesterol concentrations in any group. SHBG did not change significantly in the LNG-IUD and vaginal progesterone groups, while a slight but transient increase was seen in oral P group at 6 months. CONCLUSIONS: As the only significant harmful effect observed was a transient decrease in HDL-cholesterol in the LNG-IUD group at 6 months, each of these HRT-administration methods can be regarded as being safe in their effects on lipid metabolism.

Administration, Cutaneous↗
PubMed1998

The effect of estradiol on urodilatin production in postmenopausal women.

Urodilatin, which is structurally homologous to atrial natriuretic peptide, is most probably synthesized in the kidney. It inhibits water and sodium reabsorption and causes renal vasodilatation. However, little is known about the regulation of its synthesis, especially with regard to the influence of hormones. Transdermal administration of estradiol with low dosage producing physiologic conditions, and oral administration of estradiol with high pharmacologic dosage were investigated for their effect on urodilatin production in postmenopausal women measuring urinary excretion. Both routes of administration of estradiol increased urodilatin excretion after 28 days of treatment, the increment being statistically significant only for the transdermal route. The increased urodilatin production registered after transdermal estradiol replacement therapy may suggest that estradiol has a vasodilatory effect on the kidney.

Administration, Cutaneous↗