Dataset Information

Effect of crosslinking on the physicochemical properties of polydimethylsiloxane-based levonorgestrel intrauterine systems.

ABSTRACT: Polydimethylsiloxane (PDMS)-based levonorgestrel intrauterine systems (LNG-IUSs) such as Mirena® are long-acting drug-device combination products designed to release LNG for contraceptive purposes up to 6 years. LNG-IUSs consist of a hollow cylindrical drug-PDMS reservoir mounted with a polyethylene frame and covered by an outer PDMS membrane. PDMS is the release-controlling excipient present in both the matrix and the outer membrane. The degree of PDMS crosslinking is a key parameter in LNG-IUS manufacturing, dictating the elasticity and mechanical strength (which are critical parameters in molding and demolding of the cylindrical reservoirs). In addition, elasticity and mechanical strength are also important to prevent deformation during insertion into the uterine cavity. The objectives of this study were to investigate the impact of PDMS crosslinking on the physicochemical properties of LNG-IUSs and to develop appropriate testing methods for characterization of their mechanical strength. Formulations with different degrees of crosslinking were prepared by varying the ratio of the PDMS elastomer base and the crosslinking agent. A novel solvent swelling and extraction method was developed to determine the degree of PDMS crosslinking. The extent of crosslinking was also characterized via FTIR, Raman, ¹H NMR, DSC, TGA and dynamic mechanical analysis. As expected, formulations with higher degrees of crosslinking showed lower crystallinity. Interestingly, the less crystalline formulations showed higher Tg values and storage moduli compared to the high crystalline formulations, implying that crosslinking is the predominant parameter governing the physicochemical and mechanical properties in LNG-IUSs. Correlations were established between PDMS crosslinking and the physicochemical properties of LNG-IUSs which will be useful for quality control purposes during formulation screening and development. A better understanding of the physicochemical characteristics of these complex products will facilitate drug product development.

SUBMITTER: Fanse S

PROVIDER: S-EPMC9236551 | biostudies-literature | 2021 Nov

REPOSITORIES: biostudies-literature

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Effect of crosslinking on the physicochemical properties of polydimethylsiloxane-based levonorgestrel intrauterine systems.

Fanse Suraj S Bao Quanying Q Zou Yuan Y Wang Yan Y Burgess Diane J DJ

International journal of pharmaceutics 20211016

Polydimethylsiloxane (PDMS)-based levonorgestrel intrauterine systems (LNG-IUSs) such as Mirena® are long-acting drug-device combination products designed to release LNG for contraceptive purposes up to 6 years. LNG-IUSs consist of a hollow cylindrical drug-PDMS reservoir mounted with a polyethylene frame and covered by an outer PDMS membrane. PDMS is the release-controlling excipient present in both the matrix and the outer membrane. The degree of PDMS crosslinking is a key parameter in LNG-IUS ...[more]

PMID: 34666142

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Project description:Polydimethylsiloxane (PDMS) crosslinking density is a critical material attribute of levonorgestrel intrauterine systems (LNG-IUSs) that affects drug release and may have a significant influence on product performance and safety. Accordingly, the objective of the present work was to investigate the impact of PDMS crosslinking on the release mechanisms of LNG-IUSs and thereby achieve better product understanding. To investigate the effect of PDMS crosslinking, LNG-IUSs with varying prepolymer ratios and different mixing conditions were prepared. Accelerated and real-time in vitro release of the LNG-IUSs were conducted for up to 80 days and 7 months, respectively. Contrary to conventional understanding, formulations with higher crosslinking density showed faster drug release rates. To further understand this anomalous release behavior, the microstructure and molecular properties (using scanning electron microscopy, mercury intrusion porosimetry, polymer swelling studies, solid-state silicon NMR, and wide-angle X-ray diffraction) were investigated. Interestingly, it was revealed that high PDMS crosslinking forms a solid-state porous branched network with amorphous polymer domains facilitating fast solvent uptake (in organic solvents) and easy access to the drug particles leading to rapid mass transport of the drug molecules. Furthermore, formulations processed using planetary mixing showed higher crosslinking densities and faster drug release rates than those prepared using manual mixing. Model fitting of all LNG-IUSs were carried out using first order, two-phase (zero order plus Higuchi), and Korsmeyer-Peppas models. The first order model (which showed the best fitting for the full release profile) was used to establish correlations between the drug release rates and the PDMS crosslinking densities of LNG-IUSs. This is the first comprehensive report providing novel insights into crosslinking-induced microstructural changes and physicochemical properties that dictate drug release from LNG-IUSs.

Project description:Levonorgestrel intrauterine systems (LNG-IUSs) are polydimethylsiloxane (PDMS) based non-biodegradable complex drug-device combination products providing efficacy for up to several years based on the strength. A large amount of LNG (e.g., 52 mg in Mirena and Liletta) must be loaded in the LNG-IUS products to maintain the long-acting effect even though LNG is a potent hormone. However, the high amount of LNG not only poses the potential risk of dose dumping, but also leads to drug waste due to incomplete drug utilization close to the end of usage. It has been unclear whether the duration of usage of these products should be extended for full drug utilization or products with lower drug loading should be developed. Therefore, it is critical to understand the impact of strength (or drug loading) on drug release from LNG-IUSs. In the current study, drug reservoirs with a broad range of drug loading (from 0.5% w/w to 50% w/w) were prepared and assembled into LNG-IUSs. Different accelerated release conditions were used to perform release testing of LNG-IUSs with different drug loading. 5% to 10% variation in excipient of the LNG-IUSs did not significantly alter the drug release profiles of the LNG-IUSs. The release rate of LNG-IUSs is inversely proportional to their drug loading at high drug loading (10% w/w, 25% w/w and 50% w/w). Drug release was incomplete for LNG-IUS with low drug loading (2.5% w/w and 1% w/w) and no drug release could be detected for the LNG-IUS with 0.5% w/w drug loading. In addition, the burst effect of the LNG-IUSs with different drug loading was investigated. This is the first research report covering ultra-long duration (more than four years) of real-time drug release from LNG-IUSs with different drug loading (0.5%-50% w/w). The amount of excipient (PDMS) used in the reservoir of LNG-IUSs was determined to be not a critical quality parameter in the formulation design since LNG-IUSs (50% w/w drug loading) with up to 10% variation in excipient did not show significant differences in their release profiles. The drug release kinetics/mechanism remained the same for LNG-IUSs with drug loading ranging from 1% to 50%. In addition, the accelerated release testing methods were confirmed to be representative of the real-time release profiles and this can give confidence in extending the duration of usage for these products provided that the device remains physically intact (no tearing or damage in the outer membrane) and the release rate is within the therapeutic window. It is recommended to perform both real-time and accelerated release testing simultaneously for LNG-IUSs to understand the burst effect as well as the complete release characteristics. Lastly, drug/polymer interaction may play a role when designing LNG-IUS formulations with low drug loading (<5% w/w) since drug/polymer interaction is significant when only a small amount of drug present.

Project description:BackgroundUse of the high-dose levonorgestrel-releasing intrauterine system (LNG-IUS) has been associated with increased risk of incident depression. Evidence is lacking on the influence of use of two recently marketed low-dose LNG-IUS on risk of depression. This study aims to examine associations between use of different doses of LNG-IUS and risk of depression.MethodsWe conducted a nationwide prospective cohort study involving all first-time users of an LNG-IUS among all Danish nulliparous women aged 15-34 years with no medical history of depression, major psychiatric diseases, endometriosis, heavy menstrual bleeding, polyp, myoma, dysmenorrhoea, iron supplement use, abortion, and infertility treatment.FindingsA total of 46,565 first-time users of LNG-IUS were followed for 80,516 person-years with 1,531 incident initiations of antidepressant use observed during follow-up. Use of the high-dose LNG-IUS containing 52 mg levonorgestrel was initiated by 9,902 (21%) women, while 20,665 (44%), and 15,998 (34%) initiated use of the low-dose LNG-IUS containing 19·5 mg and 13·5 mg levonorgestrel, respectively.The age-, calendar-time-, and education-standardised incidence rates of first-time depression per 1,000 person-years at full LNG-IUS duration were 30.8 (95% CI 23·6-39·5) for the 52 mg LNG-IUS, 19·8 (95% CI 16·1; 24·0) for the 19·5 mg LNG-IUS, and 17·7 (95% CI 14·4-21·5) for the 13·5 mg LNG-IUS-. Compared to the high-dose 52 mg LNG-IUS, the adjusted number of avoided depressions per 1,000 person-years were 11·0 (95% CI 7·1-14·9) for the 19·5 mg LNG-IUS and 13·1 (95% CI 9·6-16·6) for the 13·5 mg LNG-IUS. The corresponding adjusted rate ratios were 0·77 (95% CI 0·68; 0·88) and 0·85 (95% CI 0·75-0·96). The reduced risk of depression with low-dose LNG-IUS compared to high-dose LNG-IUS was observable throughout duration of use.InterpretationUse of low-dose LNG-IUS containing 19·5 mg and 13·5 mg levonorgestrel, respectively, were associated with a reduced risk of incident depression compared to use of the high-dose 52 mg LNG-IUS. The study suggests that low-dose LNG-IUS should be preferred over the high-dose LNG-IUS for contraceptive purpose.FundingSygeforsikringen "Danmark" grant: 2021-0128.

Project description:BackgroundIn the United States, more intrauterine device (IUD) users select levonorgestrel IUDs than copper IUDs for long-term contraception. Currently, clinicians offer only copper IUDs for emergency contraception because data are lacking on the efficacy of the levonorgestrel IUD for this purpose.MethodsThis randomized noninferiority trial, in which participants were unaware of the group assignments, was conducted at six clinics in Utah and included women who sought emergency contraception after at least one episode of unprotected intercourse within 5 days before presentation and agreed to placement of an IUD. We randomly assigned participants in a 1:1 ratio to receive a levonorgestrel 52-mg IUD or a copper T380A IUD. The primary outcome was a positive urine pregnancy test 1 month after IUD insertion. When a 1-month urine pregnancy test was unavailable, we used survey and health record data to determine pregnancy status. The prespecified noninferiority margin was 2.5 percentage points.ResultsAmong the 355 participants randomly assigned to receive levonorgestrel IUDs and 356 assigned to receive copper IUDs, 317 and 321, respectively, received the interventions and provided 1-month outcome data. Of these, 290 in the levonorgestrel group and 300 in the copper IUD group had a 1-month urine pregnancy test. In the modified intention-to-treat and per-protocol analyses, pregnancy rates were 1 in 317 (0.3%; 95% confidence interval [CI], 0.01 to 1.7) in the levonorgestrel group and 0 in 321 (0%; 95% CI, 0 to 1.1) in the copper IUD group; the between-group absolute difference in both analyses was 0.3 percentage points (95% CI, -0.9 to 1.8), consistent with the noninferiority of the levonorgestrel IUD to the copper IUD. Adverse events resulting in participants seeking medical care in the first month after IUD placement occurred in 5.2% of participants in the levonorgestrel IUD group and 4.9% of those in the copper IUD group.ConclusionsThe levonorgestrel IUD was noninferior to the copper IUD for emergency contraception. (Supported by the Eunice Kennedy Shriver National Institute of Child Health and Human Development and others; ClinicalTrials.gov number, NCT02175030.).

Project description:The contraceptive effectiveness of intrauterine devices has been attributed in part to effects of a foreign body reaction on the endometrium. We performed this study to identify compare the effects on the endometrial transcriptome of intrauterine devices and combined oral contraceptives, to better understand their mechanisms of action. We collected endometrial and cervical biopsies from women using the levonorgestrel-intrauterine device, copper intrauterine device or levonorgestrel-containing combined oral contraceptives, and from women not using contraceptives (control group). Transcriptional profiling was performed with Affymetrix arrays, Principal Component Analysis and the bioconductor package limma. Pathway analysis was performed using EnrichR and Reactome 2016. In endometrial samples from copper intrauterine device users (n=13), there were no genes with statistically significant differential expression compared to controls (n=11), whereas in levonorgestrel-intrauterine device users (n=11), 2509 genes were significantly dysregulated and mapped onto several immune and inflammatory pathways. In combined oral contraceptive users (n=12), 133 genes were significantly dysregulated and mapped predominantly onto pathways involving regulation of metal ions. Both levonorgestrel-intrauterine device and combined oral contraceptive use were associated with significant downregulation of members of the metallothionein gene family. In cervical samples, none of the groups showed statistically significant differential gene expression compared to controls. In conclusion, hormonal and copper intrauterine devices differ significantly in their effects on the endometrial transcriptome, with endometrium from copper intrauterine device users being indistinguishable from luteal phase endometrium. These results suggest that the contraceptive mechanisms of intrauterine devices are unlikely to rely on a common pathway involving a foreign body reaction in the endometrium.

Dataset Information

Effect of crosslinking on the physicochemical properties of polydimethylsiloxane-based levonorgestrel intrauterine systems.

Publications

Effect of crosslinking on the physicochemical properties of polydimethylsiloxane-based levonorgestrel intrauterine systems.

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