Persistent suppression of the pituitary-gonadal system in female rats by three-month depot injectable microspheres of leuprorelin acetate

Long-acting injectable PLGA/PLA depots for leuprolide acetate: successful translation from bench to clinic

The excellent properties of polyesters combined with their ease of synthesis and modification enabled their wide use in the pharmaceutical industry. This has been translated into the approval of several injectable depots for clinical use. Long-acting depots for leuprolide acetate were among the first and most successful examples including Lupron Depot^® and ELIGARD^®. Studying these products is of great interest for researchers in both industry and academia. This will undoubtedly pave the road for the development of new as well as generic long-acting depots for a variety of drugs.

Estropause, Sex Hormones and Metal Homeostasis in the Mouse Brain

Alterations in brain metal ion homeostasis have been reported with aging and are implicated in the pathogenesis of neurodegenerative diseases. To assess whether age-related changes in hypothalamic-pituitary-gonadal (HPG) hormones might be involved in modulating brain metal ion homeostasis, we treated 7.5-month intact, sham-ovariecomized and ovariectomized C57B6SJL mice with vehicle or leuprolide acetate (for 9-months) to differentiate between whether sex steroids or gonadotropins might modulate brain metal ion concentrations. Unlike other aging mammals, there was no increase in plasma luteinizing hormone (LH) and follicle-stimulating hormone (FSH) concentrations following estropause in mice, suggesting there was sufficient residual production by the follicle depleted ovary, of sex steroids like estrogens and protein hormones like the inhibins, in order to suppress pituitary LH/FSH production. Castration on the other hand induced significant increases in circulating LH and FSH. Modulation of plasma sex steroid and gonadotropin levels did not significantly alter the concentrations of brain metals tested (Fe, Zn, Cu, Mn, Co, Ni, Al, Li), although there was a tendency for a decrease in all brain metals following ovariectomy (low estrogens and progesterone, high gonadotropins), a response that was reversed with leuprolide acetate treatment (low sex steroids, low gonadotropins). Brain Cu concentration was the only metal correlated with plasma LH (−0.37, n = 30, p < 0.05) and FSH (−0.42, n = 29, p < 0.01). This study demonstrates that sex hormones do not markedly alter brain metal ion homeostasis, unlike previously reported studies of circulating metal ion homeostasis. The role of gonadotropins in regulating metal ion homeostasis does however warrant further study.

Leuprolide Acetate, a GnRH Agonist, Improves the Neurogenic Bowel in Ovariectomized Rats with Spinal Cord Injury

BACKGROUND

Electromyographic studies have shown that external anal sphincter activity is modified in response to distension in animals with spinal cord injury. Gonadotropin-releasing hormone and its agonist leuprolide acetate have neurotrophic properties in animals with spinal cord injury.

AIM

This study was to determine the effects of leuprolide acetate treatment on electromyographic activity of the external anal sphincter and anorectal manometry in ovariectomized rats with spinal cord injury.

METHODS

Adult ovariectomized rats were divided in three groups: (a) sham of spinal cord injury, (b) spinal cord injury treated with saline solution, and (c) spinal cord injury treated with leuprolide acetate. The spinal cord injury was induced by clamping at level T9. Leuprolide acetate dosage of 10 μg/kg was proctored intramuscular for 5 weeks, commencing the day after the lesion. Electromyography of the external anal sphincter, anorectal manometry, and volume of the cecum were evaluated in all groups.

RESULTS

The electromyographic study of the external anal sphincter activity showed a significant improvement in injured rats treated with leuprolide acetate. Manometric analysis and cecum volume data obtained in animals with leuprolide acetate were very similar to those found in the sham group.

CONCLUSIONS

These results demonstrate that leuprolide acetate treatment improves the neurogenic colon in ovariectomized rats with spinal cord injury.

Pharmacokinetics and Bioavailability of the GnRH Analogs in the Form of Solution and Zn2+-Suspension After Single Subcutaneous Injection in Female Rats

BACKGROUND AND OBJECTIVES

Although many synthetic gonadoliberin analogs have been developed, only a few of them, including buserelin, were introduced into clinical practice. Dalarelin, which differs from buserelin by just one aminoacid in the position 6 (D-Ala), is not widely used so far. Gonadotropin-releasing hormone (GnRH) analogs are used to treat many different illnesses and are available in different forms like solution for injection, nasal spray, microspheres, etc. Unfortunately, none of the above drug formulations can release the hormones for 24 h. We assumed that classical suspension could solve this problem.

METHODS

Two sets of experiments were performed. In the first one, buserelin and dalarelin were injected into mature female rats in two forms: suspension, in which the analogs are bounded by Zn²⁺ ions and solution. The pharmacokinetic parameters and bioavailability of the analogs were calculated, based on their concentration in the plasma measured by high-performance liquid chromatography method (HPLC). In the second experiment, the hormones in two different forms were injected into superovulated immature female rats and then the concentration of Luteinizing hormone (LH), Follicle-stimulating hormone (FSH) and 17β-estradiol in the serum was measured by radioimmunological method.

RESULTS

The Extent of Biological Availability (EBA), calculated on the base of AUC_0-∞, showed that in the form of solution buserelin and dalarelin display, respectively, only 13 and 8 % of biological availability of their suspension counterparts. Comparing both analogs, the EBA of dalarelin was half (53 %) that of buserelin delivered in the form of solution and 83 % when they were delivered in the form of suspension. The injection of buserelin or dalarelin, in the form of solution or suspension, into superovulated female rats increased LH, FSH and estradiol concentration in the serum. However, after injection of the analogs in the form of suspension, the high concentration of LH and FSH in the serum persisted longer.

CONCLUSION

Performed studies indicate that GnRH analogs in the form of suspension have higher bioavailability than their solution counterparts. It influences the effects of their action, especially in relation to LH and FSH.

Comparative in vitro release and clinical pharmacokinetics of leuprolide from Luphere 3M Depot, a 3-month release formulation of leuprolide acetate

A 3-month depot formulation of leuprolide acetate (Luphere 3M Depot) with a mean microsphere diameter of 22.3 μm was prepared aseptically by spray-drying glacial acetic acid solution of the drug and polylactic acid, and lyophilization in a d-mannitol solution. The encapsulation efficiency and loading content of the drug in the Luphere 3M Depot were 94.7% and 9.92% (w/w), respectively. The in vitro release of leuprolide from the depot was substantially delayed and the release profile was similar to that of Lucrin Depot (Abbott Korea, Korea). The safety and pharmacokinetics of leuprolide were investigated over a period of 42 days in 20 prostate cancer patients following a subcutaneous injection of Luphere 3M or Lucrin Depot suspensions (leuprolide acetate dose of 11.25 mg) in a multi-center, randomized, single dose, parallel study. Both formulations were well tolerated by the patients and no serious adverse effects were observed during and after the study. No significant differences were observed in the maximum serum concentration (C_max) and area under the curve (AUC_last) of leuprolide between the two formulations. The results suggest comparable safety and efficacy profiles of Luphere 3M Depot and Lucrin Depot in clinical situations.

Luteinizing hormone downregulation but not estrogen replacement improves ovariectomy-associated cognition and spine density loss independently of treatment onset timing

Age-related changes in reproductive hormone levels are a well-known risk factor for the development of cognitive dysfunction and dementia in women. We and others have shown an important contribution of gonadotropins in this process. Lowering serum gonadotropin levels is able to rescue cognitive function in Alzheimer's disease and menopause models, but whether this is time-dependent and the exact mechanism through which gonadotropins regulate cognitive function is unknown. We show that pharmacologically lowering serum levels of luteinizing hormone lead to cognitive improvement immediately after ovariectomy and with a 4month interval after ovariectomy, when the benefits of 17β-estradiol are known to disappear in rodents. Importantly, we show that these improvements are associated with spine density changes at both time points. These findings suggest a role of luteinizing hormone in learning and memory and neuroplasticity processes as well as provide an alternative therapeutic strategy of menopause associated cognitive loss.

Foreign Body Granulomas Induced by Intramuscular Leuprorelin Acetate Injection for Prostate Cancer: Clinical Mimics of Soft Tissue Sarcoma

We describe two cases of florid, foreign body granulomatous reaction occurring in the upper arms of males in their eighth decade, who were undergoing treatment with depot injection of leuprorelin acetate for prostatic carcinoma. These patients presented with rapidly enlarging extremity soft tissue masses and were referred to a tertiary sarcoma center with clinical suspicion of a primary soft tissue neoplasm. The occurrence of injection site granulomas secondary to leuprorelin acetate administration is rarely known outside the urological and dermatological communities, and their recognition is important due to the spectrum of clinical differential diagnoses and potential for diagnostic confusion with metastatic prostatic cancer and primary sarcoma and in order to avoid unnecessary stress and clinical intervention for patients.

In-vitro/In-vivo comparison of leuprolide acetate release from an in-situ forming plga system

A poly (lactide-co-glycolide) (PLGA) implant was used to control the release profile of leuprolide acetate (LA) drug. The system is an in-situ polymeric precipitation system. And the formulation consisted of PLGA polymer, LA drug and N-methyl-2-pyrrolidon solvent with no additives. First, the formulation was injected into PBS solution for in-vitro studies and then it was administered to the animal models (female rats) for in-vivo release studies. The release profiles of leuprolide acetate were measured by UV spectrophotometry for a period of 28 days. The initial burst release of LA was 14% in in-vitro whereas it was 7% in in-vivo. In-vitro and in-vivo release profiles of LA had similar trends after 72 hours. However, the rate of LA release was slower in-vivo. This might be attributed to the limited diffusion process of solvent and the drug molecules. This could be due to presence of an additional pressure caused by the surrounding tissue and also the presence of small amount of water between cells in the subcutaneous site. Cross-section and surface of the implants were studied via scanning electron microscopy. Morphology of both in-vitro and in-vivo implants confirmed the release behaviours. No toxicity effects were reported in the histopathological assay. Furthermore, the pharmacological analysis showed more inactive ovaries due to release of LA.

Evaluation of the effects of testosterone and luteinizing hormone on regulation of β-amyloid in male 3xTg-AD mice

During normal aging, men experience a significant decline in testosterone levels and a compensatory elevation in levels of gonadotropin luteinizing hormone (LH). Both low testosterone and elevated LH have been identified as significant risk factors for the development of Alzheimer's disease (AD) in men. It is unclear whether changes in testosterone or LH primarily underlie the relationship with AD, and therefore may be a more suitable therapeutic target. To examine this issue, we compared levels of β-amyloid (Aβ) immunoreactivity in male 3xTg-AD mice under varying experimental conditions associated with relatively low or high levels of testosterone and/or LH. In gonadally intact mice, Aβ accumulation increased after treatment with the gonadotropin-releasing hormone agonist leuprolide, which inhibits the hypothalamic-pituitary-gonadal (HPG) axis and reduces both testosterone and LH levels. In gonadectomized (GDX) mice with low testosterone and high LH, we also observed increased Aβ levels. Treatment of GDX mice with testosterone significantly reduced Aβ levels. In contrast, leuprolide did not significantly decrease Aβ levels and moreover, inhibited the Aβ-lowering effect of testosterone. Evaluation of hippocampal-dependent behavior revealed parallel findings, with performance in GDX mice improved by testosterone but not leuprolide. These data suggest that Aβ-lowering actions of testosterone are mediated directly by androgen pathways rather than indirectly via regulation of LH and the HPG axis. These findings support the clinical evaluation of androgen therapy in the prevention and perhaps treatment of AD in hypogonadal men.

Frontiers in Alzheimer's disease therapeutics

Alzheimer disease (AD) is a progressive neurodegenerative disease which begins with insidious deterioration of higher cognition and progresses to severe dementia. Clinical symptoms typically involve impairment of memory and at least one other cognitive domain. Because of the exponential increase in the incidence of AD with age, the aging population across the world has seen a congruous increase AD, emphasizing the importance of disease altering therapy. Current therapeutics on the market, including cholinesterase inhibitors and N-methyl-D-aspartate receptor antagonists, provide symptomatic relief but do not alter progression of the disease. Therefore, progress in the areas of prevention and disease modification may be of critical interest. In this review, we summarize novel AD therapeutics that are currently being explored, and also mechanisms of action of specific drugs within the context of current knowledge of AD pathologic pathways.

Granuloma caused by subcutaneous injection of leuprorelin acetate product: Case report and histopathological findings

Leuprorelin acetate is a luteinizing hormone-releasing hormone (LH-RH) analog, which is used for chemical castration. Chemical castration treatment has an especially important role for prostate cancer. To ensure ongoing chemical castration, a novel sustained-action injection system using spherical microcapsules has been developed. We report a patient who had granuloma caused by administration of the 11.25 mg leuprorelin acetate product. Histological examination revealed many giant cells with vacuoles. On the basis of reported cases, these vacuoles are characteristic for the granuloma caused by leuprorelin acetate product. The vacuoles in the granuloma are the same size as the microcapsules, and their shape is almost spherical. We assume that the vacuoles in the granuloma are actually the microcapsules. We expect that there will be investigations regarding the procatarctic cause of granuloma formation.

Luteinizing hormone modulates cognition and amyloid-beta deposition in Alzheimer APP transgenic mice

Until recently, the study of hormonal influences in Alzheimer disease was limited to the role of sex steroids. Despite numerous epidemiological studies supporting a protective role for estrogen in Alzheimer disease, recent studies show that estrogen administration in elderly women increases the risk of disease. Reconciling these contradictory reports, we previously hypothesized that other hormones of the hypothalamic-pituitary-gonadal axis, such as luteinizing hormone, may be involved in the onset and development of the disease. In this regard, luteinizing hormone is elevated in Alzheimer disease and is known to modulate amyloidogenic processing of amyloid-beta protein precursor. Therefore, in this study, to evaluate the therapeutic potential of luteinizing hormone ablation, we administered a gonadotropin-releasing hormone analogue, leuprolide acetate, to an aged transgenic mouse model of Alzheimer disease (Tg 2576) and measured cognitive Y-maze performance and amyloid-beta deposition after 3 months of treatment. Our data indicate that luteinizing hormone ablation significantly attenuated cognitive decline and decreased amyloid-beta deposition as compared to placebo-treated animals. Importantly, leuprolide acetate-mediated reduction of amyloid-beta correlated with improved cognition. Since both cognitive loss and amyloid-beta deposition are features of Alzheimer disease, leuprolide acetate treatment may prove to be a useful therapeutic strategy for this disease.

Controlled release of levonorgestrel from biodegradable poly(D,L-lactide-co-glycolide) microspheres: in vitro and in vivo studies

Poly(D,L-lactide-co-glycolide) (PLG) biodegradable microspheres containing a contraceptive drug, levonorgestrel (LNG), were prepared using both the solvent evaporation method and a modified solvent extraction-evaporation method. The microspheres prepared with the solvent evaporation process had porous surfaces with low product yields and poor encapsulation efficiencies. On the other hand, the microspheres prepared using the modified solvent extraction-evaporation method were nonporous with encapsulation efficiencies close to 100%. In vitro drug release showed the nonporous microspheres had a lower initial burst and a slightly prolonged duration of release than those porous microspheres. In vivo release kinetics of the low burst microspheres were determined by measuring LNG plasma levels after a single intramuscular injection to female rats. At a LNG dose of 41.1 mg/kg, average plasma LNG levels were 6-10 ng/ml in the first 24 h and subsequently remained above 1 ng/ml until 126 days. The duration above the minimum effective LNG plasma level of 0.2 ng/ml was 168 days. By comparison, a similar dose of LNG microcrystals used as control produced a much higher plasma level of 15-21 ng/ml in the first day followed by a fast and continuous decline of LNG levels with a duration of only about 35 days.

Luteinizing hormone, a reproductive regulator that modulates the processing of amyloid-beta precursor protein and amyloid-beta deposition

Hormonal changes associated with the dysregulation of the hypothalamic-pituitary-gonadal (HPG) axis following menopause/andropause have been implicated in the pathogenesis of Alzheimer's disease (AD). Experimental support for this has come from studies demonstrating an increase in amyloid-beta (Abeta) deposition following ovariectomy/castration. Because sex steroids and gonadotropins are both part of the HPG feedback loop, any loss in sex steroids results in a proportionate increase in gonadotropins. To assess whether Abeta generation was due to the loss of serum 17beta-estradiol or to the up-regulation of serum gonadotropins, we treated C57Bl/6J mice with the anti-gonadotropin leuprolide acetate, which suppresses both sex steroids and gonadotropins. Leuprolide acetate treatment resulted in a 3.5-fold (p < 0.0001) and a 1.5-fold (p < 0.024) reduction in total brain Abeta1-42 and Abeta1-40 concentrations, respectively, after 8 weeks of treatment. To further explore the role of gonadotropins in promoting amyloidogenesis, M17 neuroblastoma cells were treated with the gonadotropin luteinizing hormone (LH) at concentrations equivalent to early adulthood (10 mIU/ml) or post-menopause/andropause (30 mIU/ml). LH did not alter amyloid-beta precursor protein (AbetaPP) expression but did alter AbetaPP processing toward the amyloidogenic pathway as evidenced by increased secretion and insolubility of Abeta, decreased alphaAbetaPP secretion, and increased AbetaPP-C99 levels. These results suggest the marked increases in serum LH following menopause/andropause as a physiologically relevant signal that could promote Abeta secretion and deposition in the aging brain. Suppression of the age-related increase in serum gonadotropins using anti-gonadotropin agents may represent a novel therapeutic strategy for AD.

Clinical pharmacokinetics of depot leuprorelin

Leuprorelin acetate is a synthetic agonist analogue of gonadotropin-releasing hormone. Continued leuprorelin administration results in suppression of gonadal steroid synthesis, resulting in pharmacological castration. Since leuprorelin is a peptide, it is orally inactive and generally given subcutaneously or intramuscularly. Sustained release parenteral depot formulations, in which the hydrophilic leuprorelin is entrapped in biodegradable highly lipophilic synthetic polymer microspheres, have been developed to avoid daily injections. The peptide drug is released from these depot formulations at a functionally constant daily rate for 1, 3 or 4 months, depending on the polymer type [polylactic/glycolic acid (PLGA) for a 1-month depot and polylactic acid (PLA) for depot of >2 months], with doses ranging between 3.75 and 30mg. Mean peak plasma leuprorelin concentrations (C(max)) of 13.1, 20.8 to 21.8, 47.4, 54.5 and 53 microg/L occur within 1 to 3 hours of depot subcutaneous administration of 3.75, 7.5, 11.25, 15 and 30 mg, respectively, compared with 32 to 35 microg/L at 36 to 60 min after a subcutaneous injection of 1mg of a non-depot formulation. Sustained drug release from the PLGA microspheres maintains plasma concentrations between 0.4 and 1.4 microg/L over 28 days after single 3.75, 7.5 or 15mg depot injections. Mean areas under the concentration-time curve (AUCs) are similar for subcutaneous or intravenous injection of short-acting leuprorelin 1mg; a significant dose-related increase in the AUC from 0 to 35 days is noted after depot injection of leuprorelin 3.75, 7.5 and 15mg. Mean volume of distribution of leuprorelin is 37L after a single subcutaneous injection of 1mg, and 36, 33 and 27L after depot administration of 3.75, 7.5 and 15mg, respectively. Total body clearance is 9.1 L/h and elimination half-life 3.6 hours after a subcutaneous 1mg injection; corresponding values after intravenous injection are 8.3 L/h and 2.9 hours. A 3-month depot PLA formulation of leuprorelin acetate 11.25mg ensures a C(max) of around 20 microg/L at 3 hours after subcutaneous injection, and continuous drug concentrations of 0.43 to 0.19 microg/L from day 7 until before the next injection. Recently, an implant that delivers leuprorelin for 1 year has been evaluated. Serum leuprorelin concentrations remained at a steady mean of 0.93 microg/L until week 52, suggesting zero-order drug release from the implant. In general, regular or depot leuprorelin treatment is well tolerated. Local reactions are more common after application of the 3- or 4-month depot in comparison with the 1-month depot.

Sex hormone replacement therapy reverses altered venous contractility in rats after pharmacological ovariectomy

OBJECTIVE

Female sex hormones have several important effects on the venous system. We earlier found that hormone replacement has a significant effect on venous distensibility, but effects of menopause and hormone replacement on venous contractility have never been studied. Therefore, and because the changes we found earlier in distensibility were most likely caused by alterations of contractility, we examined the changes in contractility of saphenous vein caused by depletion and replacement of sex hormones in female rats.

DESIGN

Twenty Sprague-Dawley rats were pharmacologically ovariectomized by triptorelin. Ten of these rats received combined sex hormone replacement (HRT) with estradiol propionate and medroxyprogesterone acetate. The rest were given vehicle. Ten animals without ovariectomy served as controls. After 3 months of treatment, segments of the saphenous vein were dissected. Pressure-diameter curves were recorded in relaxed, contracted, and control states.

RESULTS

Venous diameter, adjusted for body weight, was significantly decreased after pharmacological ovariectomy. HRT increased the diameter. The presence of sex hormones augmented norepinephrine contraction measured at physiological pressures (control: 19.2 +/- 2.3%; pharmacological ovariectomy: 15.2 +/- 1.4%, p < 0.05 and 17.8 +/- 2.2% following HRT). Myogenic (spontaneous) tone of the saphenous vein did not change after ovariectomy, but it was lowered by hormone replacement (control: 8 +/- 1.1%; ovariectomy: 6.9 +/- 2.5%; ovariectomy + HRT: 2.7 +/- 1.1%, p < 0.05).

CONCLUSIONS

Sex hormone depletion induces significant alterations in contractility of the saphenous vein, which could perturb venous capacitance function and distensibility. This effect has a potential role in the development of hypertension and venous varicosity, and these changes could possibly be prevented by HRT.

Biodegradable polymers for ocular drug delivery

A variety of ocular drug delivery systems, including a controlled release of the drug, drug targeting, and penetration enhancement of the drug, have been investigated. Biodegradable polymers have been widely used as the drug carrier for controlled-release systems. Biodegradable polymers release the drug as they themselves degrade and are finally absorbed within the body. Several ocular drug delivery systems using different kinds of biodegradable polymers have been studied. In this article, we describe the fundamental mechanisms of drug delivery systems, polymer erosion and drug release, and then review those systems using the most popular biodegradable polymers, poly(lactic acid) and poly(lactic-glycolic acid).

Sex hormone replacement therapy reverses decreased venous distensibility in pharmacologically ovariectomized rats

OBJECTIVE

To test the effect of female sex hormone depletion and replacement on the distensibility and geometry of the saphenous vein in female rats.

DESIGN

Twenty Sprague-Dawley rats were pharmacologically ovariectomized by triptorelin. Ten of these animals received combined hormone replacement with estradiol and medroxyprogesterone acetate. The rest were given vehicle. Ten animals kept parallel without pharmacological ovariectomy served as controls. After 3 months of treatment, a segment of the saphenous vein was dissected. Pressure-diameter curves were recorded in relaxed, contracted, and control states using a microangiograph.

RESULTS

Pharmacological ovariectomy lowered venous wall distensibility measured in contraction (at P=8 mm Hg: 4.41+/-1.21*10(-3) m2/N vs. control: 0.79+/-0.14*10(-3) m2/N; p < 0.05). Hormone replacement partially restored this value (1.8+/-0.49*10(-3) m2/N). No alterations in distensibility were found in the relaxed state. After adjusting for body weight, we found that pharmacological ovariectomy lowered venous inner radius significantly compared with control (p < 0.05), whereas hormone replacement increased it compared with pharmacological ovariectomy (p < 0.05) and more significantly compared with control (p < 0.01).

CONCLUSION

Sex hormone depletion induces significant alterations in venous distensibility, presumably by inducing initial remodeling of the venous wall. Hormone dependency of distensibility differed in relaxed and contracted states of the vein, so some alterations of contractile elements of the wall may be hypothesized. Lower distensibility of the venous wall found after pharmacological ovariectomy could be part of the mechanism of predisposition for postmenopausal hypertension. This can be reversed by female sex hormone replacement.

The manufacturing techniques of various drug loaded biodegradable poly(lactide-co-glycolide) (PLGA) devices

A considerable research has been conducted on drug delivery by biodegradable polymeric devices, following the entry of bioresorbable surgical sutures in the market about two decades ago. Amongst the different classes of biodegradable polymers, the thermoplastic aliphatic poly(esters) like poly(lactide) (PLA), poly(glycolide) (PGA), and especially the copolymer of lactide and glycolide, poly(lactide-co-glycolide) (PLGA) have generated immense interest due to their favorable properties such as good biocompatibility, biodegradability, and mechanical strength. Also, they are easy to formulate into different devices for carrying a variety of drug classes such as vaccines, peptides, proteins, and micromolecules. Also, they have been approved by the Food and Drug Administration (FDA) for drug delivery. This review discusses the various traditional and novel techniques (such as in situ microencapsulation) of preparing various drug loaded PLGA devices, with emphasis on preparing microparticles. Also, certain issues about other related biodegradable polyesters are discussed.

A case of atypical absence seizures induced by leuprolide acetate

We report a case of a 13-year-old female with atypical absence seizures induced by prolonged administration of long-acting leuprolide acetate (LA). This patient had brain involvement resulting from chemotherapy and radiotherapy for a medulloblastoma. At 13 years of age, administration of long-acting LA was started. After the third dose of long-acting LA, atypical absence seizures appeared. After discontinuing long-acting LA, the seizures stopped without administration of any antiepileptic drugs. However, 2 years, 6 months later, the same seizures again appeared. On the basis of the findings of endocrinologic investigations and the reported data of pharmacokinetics of LA, we speculate that her seizures were induced by LA and that the seizures were associated with the presence of brain damage in the patient. Care should therefore be taken when using long-acting LA or other gonadotropin-releasing hormone analogues for pediatric patients with diffuse brain damage.

Effects of combined sex hormone replacement therapy on small artery biomechanics in pharmacologically ovariectomized rats

OBJECTIVES

The purpose of this study was to determine the effects of long-term combined sexual hormone replacement therapy on the biomechanical properties of the small artery wall in castrated female rats.

METHODS

30 non-pregnant mature female Sprague-Dawley rats were pharmacologically ovariectomized with 750 microg/kg triptorelin im. every 4th week. Ten of them received combined hormone replacement in form of 15 mg/kg medroxyprogesterone acetate (MPA) im. every 2 weeks and 450 microg/kg estradiol propionate im. once a week. Ten castrated animals received MPA only. Ten control, castrated animals were given the vehicles of these steroids. Ten other animals were kept parallelly, receiving the vehicles of all drugs (control animals). After 12 weeks of treatment cylindrical segments of the saphenous artery were isolated and cannulated at both ends and subjected to in vitro microarteriographic test. Pressure diameter curves, in the range of 0-200 mmHg, were recorded from segments in normal Krebs-Ringer (nKR) solution, in contraction with norepinephrine (1.6 x 10(-5) M), and then in relaxation with papaverine (2.8 x 10(-5) M). Biomechanical parameters were calculated based on the pressure diameter curves.

RESULTS

Combined hormone replacement therapy significantly increased the passive diameter of small arteries, as compared to those from ovariectomized animals without hormone replacement. MPA monotherapy did not alter the vessel diameter, the inner radii at 100 mmHg intraluminal pressure were, 300+/-9 microm in the control castrated, 340+/-7 microm in the estradiol + MPA replaced and 306+/-8 microm in the MPA treated groups (P < 0.05 between the control castrated and the combined treatment groups). The vascular reactivity to norepinephrine or papaverine was not changed significantly either by combined hormone replacement or by MPA monotherapy when compared with ovariectomized controls. No significant alterations were found in wall thickness and distensibility.

CONCLUSIONS

These results suggest that chronic medroxyprogesterone pretreatment does not influence the geometric, elastic and contractile properties of small arteries in castrated female rats. The combination of MPA + estradiol increased the morphological lumen: the morphological vasodilatation induced by estrogen, described earlier, was not affected by the addition of this progestin to the regimen.

Controlled drug delivery by biodegradable poly(ester) devices: different preparative approaches

There has been extensive research on drug delivery by biodegradable polymeric devices since bioresorbable surgical sutures entered the market two decades ago. Among the different classes of biodegradable polymers, the thermoplastic aliphatic poly(esters) such as poly(lactide) (PLA), poly(glycolide) (PGA), and especially the copolymer of lactide and glycolide referred to as poly(lactide-co-glycolide) (PLGA) have generated tremendous interest because of their excellent biocompatibility, biodegradability, and mechanical strength. They are easy to formulate into various devices for carrying a variety of drug classes such as vaccines, peptides, proteins, and micromolecules. Most importantly, they have been approved by the United States Food and Drug Administration (FDA) for drug delivery. This review presents different preparation techniques of various drug-loaded PLGA devices, with special emphasis on preparing microparticles. Certain issues about other related biodegradable polyesters are discussed.

Properties of a peptide containing DL-lactide/glycolide copolymer nanospheres prepared by novel emulsion solvent diffusion methods

Novel emulsion solvent diffusion methods in water or oil were developed to prepare the peptide (TRH and elcatonin)-loaded PLGA nanospheres, via the coprecipitation of drug and polymer in the emulsion droplets induced by the diffusion of solvent. The PLGA nanospheres prepared by the emulsion solvent diffusion method in water were unimodally dispersed particles with an average diameter of about 250 nm, whereas those prepared by the emulsion solvent diffusion method in oil and the phase separation method exhibited bimodal distribution with average diameter of about 700 and 800 nm, respectively. The content and recovery of the peptide and nanospheres prepared by the emulsion solvent diffusion method in oil were superior to those of nanospheres prepared using other methods. The drug release properties from nanospheres depended strongly on their preparation processes. The nanospheres prepared by the emulsion solvent diffusion method in oil, released the drug continuously over 14 days, the rate of which was determined by the diffusion of drug in the rigid matrix structure of the nanosphere. The drug release behavior of nanospheres prepared by the phase separation method exhibited a triphasic release pattern with an initial burst and an induction period followed by the diffusion of drug through the walls of the reservoir type nanospheres, which were produced via the phase separation of polymer deposited around the emulsion droplets of the drug.

One- and three-month release injectable microspheres of the LH-RH superagonist leuprorelin acetate

The biodegradable polymers poly(lactic/glycolic acid) (PLGA) and poly(lactic acid) (PLA) were used as wall materials in the preparation of microspheres (msp) containing the LH-RH superagonist leuprorelin (leuprolide) acetate. A novel W/O/W emulsion-solvent evaporation method was devised for the preparation of msp containing this water-soluble peptide. This method achieved high entrapment efficiency and sustained drug release over a long period predominantly due to polymer bioerosion. The msp are fine microcapsules with polycores containing the peptide at a high concentration and are easily injectable through a conventional fine needle. Leuprorelin msp made with PLGA(75/25)-14,000 or PLA-15,000 released the drug in a zero-order fashion, maintained constant serum drug levels and attained persistent objective suppression of the pituitary-gonadal system ('chemical castration') over 1 or 3 months after i.m. or s.c. injection into animals. These results indicate that depot formulations may be potentially useful in the therapy of endocrine diseases in humans. In this paper, studies on the formulation, drug release and pharmacological effects in animals for these leuprorelin depot formulations are reviewed.