Comparison of pharmacokinetic profiles of a 17 beta-estradiol gel 0.6 mg/g (Gelestra) with a transdermal delivery system (Estraderm TTS 50) in postmenopausal women at steady state

Strategies for transdermal drug delivery against bone disorders: A preclinical and clinical update

The transdermal drug delivery system is an exceptionally safe and well-tolerable therapeutic approach that has immense potential for delivering active components against bone-related pathologies. However, its use is limited in the current clinical practices due to the low skin permeability of most active drugs in the formulation. Thus, innovations in the methodologies of skin permeation enhancement techniques are suggested to overcome this limitation. Although various transdermal drug delivery systems are studied to date, there are insufficient studies comparing the therapeutic efficacy of transdermal delivery systems to oral delivery systems. Thus, creating a decision-making dilemma between oral or transdermal therapies. Therefore, a timely review is inevitable to develop a platform for future researchers to develop next-generation transdermal drug delivery strategies against skeletal diseases that must be convenient and cost-effective for the patients with improved therapeutic efficacy. Here, we will outline the most recent strategies that can overcome the choice limitation of the drug and enhance the transdermal adsorption of various types of drugs to treat bone disorders. For the first time, in this review paper, we will highlight the preclinical and clinical studies on the different transdermal delivery methods. Thus, providing insight into the current therapeutic approaches and suggesting new directions for the advancements in transdermal drug delivery systems against bone disorders.

Comparison of the analytical methods (solid state NMR, FT-IR, PXRD) in the analysis of the solid drug forms with low concentration of an active ingredient - 17-β-estradiol case

The application of various techniques (FT-IR, PXRD, ssNMR) in the analysis of solid dosage forms with low concentration of an API (17-β-estradiol hemihydrate, EBHH) was tested. PXRD analysis of Estrofem Mite tablets (EMT) confirmed the presence of the main crystalline excipient, α-lactose monohydrate. In the PXRD pattern of EMT the strong background from polycrystalline excipients, i.e. hydroxypropylmethylcellulose and corn starch was observed. FT-IR spectra were characterized by the broad peaks in the 3000-3600cm^-1 region of the OH stretching modes coming from multiple hydrogen bonds that are present in the structures of the excipients (α-lactose monohydrate, corn starch) and API. The only technique which unambiguously confirmed the presence of an API in the EMT was solid state NMR. Despite the tabletting process each of the EMT component retained its characteristic features like relaxation time and T_1ρ^I. Due to the possibility of the manipulation in the experimental registration parameters like recycle delay (RD), evolution time (τ) and contact time (CT) it was possible to perform multiple experiments on the same sample of EMT. The most valuable were the inversion recovery CP experiments in which, by setting the proper values of τ, it was possible to selectively observe the signals of the chosen component of the drug formulation. In this study the great potential of solid state NMR in the analysis of solid dosage forms, as the unique technique that combines the possibility of selective observation of the chosen signals with the non destructive character that enables further analysis of the same sample, was confirmed.

Transdermal patches: history, development and pharmacology

Transdermal patches are now widely used as cosmetic, topical and transdermal delivery systems. These patches represent a key outcome from the growth in skin science, technology and expertise developed through trial and error, clinical observation and evidence-based studies that date back to the first existing human records. This review begins with the earliest topical therapies and traces topical delivery to the present-day transdermal patches, describing along the way the initial trials, devices and drug delivery systems that underpin current transdermal patches and their actives. This is followed by consideration of the evolution in the various patch designs and their limitations as well as requirements for actives to be used for transdermal delivery. The properties of and issues associated with the use of currently marketed products, such as variability, safety and regulatory aspects, are then described. The review concludes by examining future prospects for transdermal patches and drug delivery systems, such as the combination of active delivery systems with patches, minimally invasive microneedle patches and cutaneous solutions, including metered-dose systems.

A review of transdermal nonpatch estrogen therapy for the management of menopausal symptoms

During the transition into menopause, women may experience a wide range of symptoms that negatively impact quality of life. The vasomotor symptoms (VMS) of hot flushes and night sweats are common and vary widely in frequency and severity. The treatment of menopause-associated VMS is a frequently encountered clinical challenge, with the goal of tailoring treatment for each individual woman's needs. Estrogen therapy is the most effective treatment for menopausal VMS. Current guidelines suggest that estrogen therapy be prescribed at the lowest effective dose for the shortest duration of time. Transdermal estrogen therapy has dominated the menopause prescribing practice in Europe for decades; however, in the United States, oral estrogen therapy is most commonly prescribed. Transdermal estrogen therapy can be prescribed at considerably lower doses than oral therapy yet has similar efficacy on the symptoms of menopause. Emerging research demonstrates transdermal estrogen, particularly 17beta-estradiol, may have the potential for fewer health risks than oral estrogen therapy. This review article discusses the spectrum of menopausal symptoms, addresses prevailing issues in the treatment of menopause, elaborates on the risks and benefits of oral and transdermal hormone therapies, and focuses on five nonpatch transdermal estradiol therapies currently available in the United States.

Insulin secretion and clearance after subacute estradiol administration in postmenopausal women

CONTEXT

Data from large clinical trials of postmenopausal women suggest that the incidence of diabetes is reduced in women randomized to estrogen-based hormone therapy when compared with placebo. Whether this is due to an effect of estrogen on insulin or glucose metabolism remains unclear.

OBJECTIVE

Our objective was to test the hypothesis that estradiol (E(2)) increases insulin secretion and clearance.

DESIGN

Serum insulin and C-peptide (CPEP) responses to hyperglycemia (250 mg/dl) plus iv L-arginine were measured on 2 separate days, with (EST) and without [control (CON)] subacute (24 h) transdermal E(2) administration.

STUDY PARTICIPANTS

There were 11 postmenopausal women (mean +/- sd; 55 +/- 4 yr) included in this study.

MAIN OUTCOMES

Insulin secretion and clearance were estimated from the CPEP area under the curve and the molar ratio of CPEP to insulin area under the curve, respectively. Mean glucose disposal rate (GDR) was estimated from the rate of glucose infusion during the final 30 min of the hyperglycemic clamp.

RESULTS

There were no differences in insulin secretion or clearance between the EST and CON days. Fasting glucose was lower on the EST compared with the CON (93 +/- 6 vs. 98 +/- 8 mg/dl), but mean GDR was not different. However, when one outlier was excluded from analysis, GDR was increased after EST compared with CON. Furthermore, a strong inverse association was observed between years since menopause and E(2)-mediated changes in GDR (r = -0.794; P = 0.004).

CONCLUSIONS

Contrary to our hypothesis, 24-h transdermal E(2) administration did not alter insulin secretion or clearance in postmenopausal women. However, a longer time since menopause was associated with a reduced effect of E(2) to increase glucose uptake.

Effects of non-oral postmenopausal hormone therapy on markers of cardiovascular risk: a systematic review

OBJECTIVE

To review the effects of non-oral administration of postmenopausal hormone therapy (HT) on risk markers for atherosclerotic and venous thromboembolic disease.Non-oral postmenopausal HT appears not to increase venous thromboembolic risk, whereas the effect on coronary heart disease risk is less clear.

DESIGN

Systematic review of literature obtained from MEDLINE, EMBASE, and CENTRAL databases from 1980 until and including April 2006. Terms for "postmenopausal hormone therapy" and for "non-oral administration" were combined in the search.

SETTING

Randomized clinical trials.

PATIENT(S)

Postmenopausal women, both healthy and with established cardiovascular disease or specified cardiovascular risk factors

INTERVENTION(S)

Non-oral HT (e.g., transdermal or intranasal) compared with oral HT or no treatment/placebo.

MAIN OUTCOME MEASURE(S)

Lipoprotein(a), homocysteine, C-reactive protein (CRP), cell adhesion molecules, markers of endothelial dysfunction, coagulation, and fibrinolysis.

RESULT(S)

Seventy-two studies investigating either transdermal or intranasal administration were included. For non-oral HT, decreases in lipoprotein(a), cell adhesion molecules, and factor VII generally were significant, resistance to activated protein C (APCr) was slightly increased, and other markers including CRP and homocysteine did not change. Compared with oral HT, changes in CRP and APCr were smaller, changes in cell adhesion molecules and some fibrinolytic parameters tended to be smaller, whereas changes in other factors including lipoprotein(a) and homocysteine did not differ.

CONCLUSION(S)

Potentially unfavorable changes seen with oral HT on two important markers, CRP and APCr, are substantially smaller with non-oral HT. Non-oral HT has minor effects on the other cardiovascular risk markers studied. Therefore, compared with oral HT, non-oral HT appears be safer with respect to atherosclerotic and venous thromboembolic disease risk.

Cutaneous Estradiol Permeation, Penetration and Metabolism in Pig and Man

AIM AND METHODS

Drug development in dermatotherapy and also development of transdermal therapeutic systems (TTS) demand high-predictive in vitro models to estimate drug levels in skin and systemic uptake. Here we compare three ready-to-use models, reconstructed human epidermis, split porcine skin and the perfused porcine forelimb. 17beta-Estradiol (E(2)), which is highly metabolized by skin cells, serves as model drug since E(2) application is of high relevance in hormone replacement therapy while topical E(2) may promote wound healing. E(2) TTS, gel and an ethanolic solution were investigated for cutaneous penetration, permeation and metabolism.

RESULTS

E(2) TTS enabled an E(2) uptake of 42.9% of the applied dose accompanied by a high percentage of E(2) metabolism (30% of the penetrated dose) in the perfused porcine forelimb. In Franz cell experiments with reconstructed human epidermis and split porcine skin, the gel allowed an E(2) uptake of 41.7 and 22.9% of the applied dose accompanied by a high E(2) metabolism (42.6 and 28.6% of the penetrated dose). Due to toxic effects of the vehicle, this was not true with an ethanolic solution, then E(2) permeation and metabolism were clearly diminished. Most importantly, the in vitro models proved to be predictive with respect to the E(2)/estrone ratio in female plasma under transdermal hormone replacement therapy.

CONCLUSION

In vitro tests should reduce the need for both animal and human studies for cutaneous uptake and metabolism in the future.

Low-Dose Estrogen Therapy for Menopausal Women: A Review of Efficacy and Safety

BACKGROUND

Recent adverse events involving research of traditional estrogen therapy have led to interest in lower-than-standard doses of menopausal estrogen therapy.

METHOD

The Medline (1966-present) database was searched for randomized controlled trials (keywords: low-dose estrogen, minimum dose AND estrogen, menopause, and osteoporosis) regarding hot flashes, endometrial hyperplasia, vaginal bleeding, breast tenderness, and bone density. Studies are only a few years in duration.

RESULTS

The decrease in hot flashes with half-strength estrogens, range 60%-70%, is less than the 80%-90% reduction with standard dosing. Some low-dose preparations preserve lumbar and femoral bone density (although the degree of effect and quality of evidence vary among preparations). Bone density effects are dose dependent for conjugated equine estrogen (CEE), transdermal estradiol ethinyl (E(2)), norethindrone acetate (E(2)/NETA), oral E(2), and esterified estrogens. Bone preservation is likely to be less efficacious with low-dose estrogens than with traditional doses. Low-dose estrogen alone may not protect bone unless adequate calcium is given. Breast tenderness and skeletal effects are likely dose dependent. The longest endometrial safety data are 2-year data, reported for 5 microg/1 mg EE(2)/NETA and for 0.3 mg/day esterified estrogens. Some low-dose preparations have better vaginal bleeding profiles than do higher dose preparations. Breast tenderness is not totally averted with new lower-dose preparations. There are no fracture, breast cancer, or cardiovascular outcome data and a general lack of direct head-to-head comparisons involving low-dose preparations.

CONCLUSIONS

Serious adverse effects linked with traditional doses of estrogens may not be averted with lower-dose preparations, and low-dose preparations should not yet be emphasized as being safer than traditional (e.g., 0.625 mg/day CEE doses).