Highly Soluble Drugs Directly Granulated by Water Dispersions of Insoluble Eudragit® Polymers as a Part of Hypromellose K100M Matrix Systems.

The aim of the present study was to investigate the suitability of insoluble Eudragit® water dispersions (NE, NM, RL, and RS) for direct high-shear granulation of very soluble levetiracetam in order to decrease its burst effect from HPMC K100M matrices. The process characteristics, ss-NMR analysis, in vitro dissolution behavior, drug release mechanism and kinetics, texture profile analysis of the gel layer, and PCA analysis were explored. An application of water dispersions directly on levetiracetam was feasible only in a multistep process. All prepared formulations exhibited a 12-hour sustained release profile characterized by a reduced burst effect in a concentration-dependent manner. No effect on swelling extent of HPMC K100M was observed in the presence of Eudragit®. Contrary, higher rigidity of formed gel layer was observed using combination of HPMC and Eudragit®. Not only the type and concentration of Eudragit®, but also the presence of the surfactant in water dispersions played a key role in the dissolution characteristics. The dissolution profile close to zero-order kinetic was achieved from the sample containing levetiracetam directly granulated by the water dispersion of Eudragit® NE (5% of solid polymer per tablet) with a relatively high amount of surfactant nonoxynol 100 (1.5%). The initial burst release of drug was reduced to 8.04% in 30 min (a 64.2% decrease) while the total amount of the released drug was retained (97.02%).

Feasibility of radiolabeled small molecule permeability as a quantitative measure of microbicide candidate toxicity.

OBJECTIVE: To determine the feasibility of using quantitative changes in vaginal permeability to small molecules as a measure of candidate microbicide toxicity. STUDY DESIGN: Controlled, open-labeled, prospective study. Seven healthy women received a single vaginal dose of hydroxyethylcellulose gel (HEC), nonoxynol-9 (N-9) or K-Y Jelly. Each gel was radiolabeled with a small molecule ((99m)Tc-DTPA) followed by 12-h blood and urine collection. Pharmacokinetic (PK) parameters of (99m)Tc-DTPA were calculated to compare the impact of each gel on vaginal permeability. Each woman served as her own control. The Friedman test with post hoc Wilcoxon test was used to detect differences among the gels. RESULTS: Vaginal permeability of (99m)Tc-DTPA was highest for the N-9 radiolabel. N-9 plasma area under the concentration curve was 2.7-fold higher (p=.04), and peak concentration was threefold higher (p=.04) compared to HEC. There were no significant PK parameter differences between HEC and K-Y Jelly or between N-9 and K-Y Jelly. Cumulative dose-adjusted median (interquartile range) 12-h timed urine gamma activity was 66.70 × 10(-4)µCi (27.90-152.00) following HEC dosing, 103.00 × 10(-4)µCi (98.20-684.00) following N-9 gel dosing and 20.30 × 10(-4)µCi (11.10-55.90) following K-Y gel dosing. The differences between urine HEC and K-Y Jelly (p=.047) and between N-9 and K-Y Jelly (p=.016) were statistically significant. CONCLUSIONS: It is feasible to measure differences in vaginal permeability among vaginal gels using a radiolabeled small molecule, though there are permeability differences that require a nuanced understanding of gel composition to interpret the results. IMPLICATIONS: Establishing the safety of both vehicle and active pharmaceutical ingredient is an essential task in microbicide development, to be determined as soon as possible. This study suggests that a combination of microbicide toxicity assessments, that is, cervicovaginal permeability, inspection and histopathology, may need to be studied simultaneously.

Quantitative determination of microbicidal spermicide 'nonoxynol-9' in rabbit plasma and vaginal fluid using LC-ESI-MS/MS: application to pharmacokinetic study.

Nonoxynol-9 (N-9), a microbicidal spermicide, has been in use as an over-the-counter contraceptive since the 1960s. A detailed account of its pharmacokinetic profile using highly sensitive detection method has not been reported yet. We developed and validated a rapid, selective and sensitive high-performance liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) method for N-9 detection in plasma and simulated vaginal fluid. The analytes were quantified using reverse phase Thermo Accucore C18 (150 mm × 4.6mm, 5 µm) column with isocratic elution using acetonitrile: 0.1% formic acid in triple distilled water (90:10, v/v) as mobile phase. The ionization was optimized using ESI (+) and selectivity was achieved by tandem mass spectrometric analysis using MRM transition, m/z 617.4→133.2 for N-9 and m/z 180.1→138.1 for phenacetin. The method was linear over the range 0.195-100 ng/mL. The method was accurate and precise with intra-batch and inter-batch accuracy (% bias) of less than ± 15% and precision (% CV) of <15% for N-9. The mean peak plasma concentration (Cmax) 4.87 ± 0.37 ng/mL was achieved 1.0h after vaginal application with terminal half-life 1.45 ± 0.07 h in rabbits. The validated method was successfully applied for pharmacokinetic study of N-9 in rabbits after vaginal administration.

Update on nonoxynol-9 as vaginal spermicide.

Nonoxynol-9 (N-9) is a typical surfactant. For more than 30 years that very property of N-9 has been successfully exploited for its spermicidal action. It is available as an over-the-counter, locally acting vaginal spermicide. The suitability of N-9 as a spermicide is elaborated in this article. The reasons why N-9 may fail as a contraceptive are discussed. In spite of many drawbacks, which are mentioned in the article, N-9 is still often resorted to as a locally acting contraceptive. The review ends with suggestions to alter the molecular structure of N-9 and to adjust the dosages.

In vitro release of nonoxynol-9 from silicone matrix intravaginal rings.

The controlled-release characteristics of matrix silicone intravaginal rings loaded with between 100 and 971 mg of nonoxynol-9 have been investigated with a view to developing a ring that may offer a new female-controlled method for the prevention of transmission of sexually transmitted diseases, particularly HIV. Intravaginal rings containing 253, 487 and 971 mg of nonoxynol-9 provided a daily release of 2 mg or more over the 8-day release period, the minimal amount of nonoxynol-9 considered to provide an effective vaginal concentration for the prevention of HIV. Furthermore, the maximum daily release of N9 was about 6 mg, an amount significantly smaller than that observed for other nonoxynol-9 products whose large daily doses may in fact increase the occurrence of HIV by causing epithelial damage to the vaginal tissue. The release mechanism of the liquid nonoxynol-9 from the intravaginal rings has also been investigated and compared to models describing the release of solid drugs from the rings. It has been demonstrated through release studies and surface microscopy that a drug depletion zone is not established in such liquid-loaded intravaginal ring systems, with implications for the release kinetics.

Synthesis of novel iodinated derivatives of nonoxynol-9 and their bioavailability in rats.

The absorption and distribution of iodinated derivatives of nonoxynol-9, after vaginal administration in rats, were compared with results reported for [14C] nonoxynol-9. Mono-iodinated nonoxynol-9 was synthesized in addition to the radiolabeled derivative incorporating iodide-125 ([125I]). Six hours after dosing, test rats were euthanized and selected tissues were excised and assessed for radioactivity. Levels of radioactive markers in the reproductive system were substantial for both [14C] and [125I]. It was concluded that [125I] mono-iodinated nonoxynol-9 and [14C] nonoxynol-9 possessed similar bioavailability.

Distribution of a spermicide containing Nonoxynol-9 in the vaginal canal and the upper female reproductive tract.

Topical, intravaginal microbicides and spermicides are greatly needed to prevent transmission of sexually transmitted diseases and/or unwanted pregnancies. The development of such compounds is a high research priority. The presumed method of action of existing, or novel, microbicides/spermicides is to provide a chemical barrier to the vaginal epithelium preventing exposure to micro-organisms. Other intravaginal products are used to treat vaginal bacteria of fungal infections. Little is known, however, about the actual or optimal initial distribution and subsequent spread of medications placed in the vagina. We describe a sensitive new technique to quantify the spread of a gel placed in the vagina using magnetic resonance imaging (MRI). Five millilitres of an over-the-counter spermicide containing Nonoxynol-9 was mixed with Gadolinium. MRI was used to quantify spread of the mixture 10 min after insertion with a standard applicator. We demonstrated contiguous spread of gel throughout the vagina. The coverage of material was thicker in the upper vagina than in the lower vagina. We also demonstrated, for the first time, that spermicidal compounds may migrate from the vaginal canal into the endocervix within 10 min of insertion. This finding suggests that topical microbicides/spermicides may act both in the vaginal canal and in the upper female genital tract.

Comparative in vitro percutaneous absorption of nonylphenol and nonylphenol ethoxylates (NPE-4 and NPE-9) through human, porcine and rat skin.

The purpose of this study was to assess the percutaneous absorption of nonylphenol (NP) and the nonylphenol ethoxylates, NPE-4 and NPE-9, in human, porcine and rat skin. In vitro studies with the NPEs were conducted for 8 h in flowthrough diffusion cells using topical solutions of 0.1, 1.0 and 10% in PEG-400 or 1% in water (NPE-9 only). NP absorption was assessed as a 1% solution in PEG-400. All compounds were 14C ring-labeled and radioactivity in perfusate was monitored over time. Skin deposition was measured at the termination of the experiment. Absorption into perfusate and total penetration (compound absorbed plus compound sequestered in skin) were calculated. Absorption of NPE-4, NPE-9 and NP was similar across all species at less than 1% of the applied dose over 8 h. Penetration was generally below 5% of applied dose, the majority located in the stratum corneum. In all species and for both NPEs, the fraction of dose absorbed was highest for the lowest applied dose. Absorptions expressed as actual mass absorbed over 8 h were similar (approximately 0.3 microg/cm2) across all concentrations. Penetration, but not absorption, was greater from a water vehicle compared to a PEG-400 vehicle, particularly in rat skin. These studies suggest that NP, NPE-4 and NPE-9 were minimally absorbed across skin from all three species. Fractional absorption was concentration-dependent, making the actual absorbed flux constant across all doses.

[Absorption of a vaginal contraceptive, nonoxynol (polyoxyethylene nonylphenyl ether) and its metabolism to nonylphenol in female rabbits].

After intravaginal administration of a spermicide, nonoxynol (polyoxyethylene nonylphenyl ether, NPE) in female rabbits, the pharmacokinetics of NPE were examined by the HPLC method. The plasma levels after administration of NPE revealed a considerable amount of absorption of NPE into the circulation and the bioavailability after intravaginal administration was calculated to be 66% by comparison with that after intravenous administration. Unchanged NPE was not excreted into the urine in significant amounts even on intravenous administration. Nonylphenol (NP), a presumed metabolite of NPE, was simultaneously analyzed using GC-MS to assess the risk by its endocrine disrupting effects. Although the NP concentrations in the plasma were all below the lower limit of quantitation (10 ng/ml), small amounts of NP and its glucuronide conjugate were detected in the urine after intravaginal administration of NPE. Thus it was suggested that at least part of NPE absorbed in the circulation was metabolized to give NP. However, the sum of NP and its conjugate excreted in the urine was very small amounts (0.22% of dose). Therefore, it was assumed that the production of NP was not in the major pathway of the NPE metabolism.

Duration of vaginal retention and potential duration of antiviral activity for five nonoxynol-9 containing intravaginal contraceptives.

OBJECTIVE: The purpose of this study was to determine the vaginal retention of five nonoxynol-9 intravaginal contraceptives. METHOD: An open-label crossover study in 10 premenopausal volunteers was performed at an outpatient clinical research center. The outcomes are described utilizing the median and range. RESULT: At 8 h post-instillation, the median amounts of nonoxynol-9 present in the vagina were: Delfon 7.68 mg, Conceptrol 5.18 mg, Advantage 24 1.95 mg, VCF 1.74 mg, and Semicid 1.51 mg respectively. Our calculated theoretical minimal amount needed to protect against HIV infection is 2.00 mg. CONCLUSION: The best vehicle for retaining nonoxynol-9 in the vagina appears to be foam. Further research in the effectiveness of nonoxynol-9 in prevention of the spread of HIV infection should be directed toward the use of foam vehicles to deliver nonoxynol-9 to the vagina.

Factors influencing nonoxynol-9 permeation and bioactivity in cervical mucus.

The effects of delivery gel pH and osmolarity on both the mass transport and 'biodiffusion' of the spermicide nonoxynol-9 (N9) in bovine cervical mucus were evaluated. Delivery gels were calcium chloride crosslinked alginate containing 3% N9, and were manufactured over a pH range of 3.4 to 5.9 and an osmolarity range of 300 to 900 mosmol. Mass transfer parameters (diffusion coefficients and total drug loading) were determined using a new UV spectrophotometric technique while biodiffusion (the diffusion distance into mucus at which sperm are killed) was assessed using the Double Ended Test. It was found that delivery gel pH had a significant effect on spermicidal efficacy of the alginate-N9 system; biodiffusion increased with decreasing pH. Actual N9 diffusion into mucus was found to be influenced by both the delivery gel pH and osmolarity. At high N9 concentration (near the gel/mucus interface), mass transport tended to decrease with decreasing pH at the highest osmolarity. At low concentration, mass transport tended to decrease with increasing osmolarity and decrease with increasing pH at the highest osmolarity. The difference between low and high concentration behavior can be attributed to N9 micelle formation. These findings are interpreted in the context of the design of intravaginal drug delivery vehicles for spermicides.

An evaluation of the amount of nonoxynol-9 remaining in the vagina up to 4 h after insertion of a vaginal contraceptive film (VCF) containing 70 mg nonoxynol-9.

The objectives of this study were to determine the amount of nonoxynol-9 (N-9) remaining in the vagina 30 min and 1, 1.5, 2, and 4 h after vaginal insertion of a single sheet of VCF containing 70 mg N-9 and to compare these results to the manufacturer's instructions for use of this product. A new method of vaginal lavage was used to obtain samples for N-9 determination. This was an open-label, noncomparative, pharmacokinetic study in 12 healthy women volunteers not at risk for pregnancy. The study consisted of a screening visit followed by five test visits approximately 1 month apart and a final visit 1 week after all test visits were completed. At each test visit, the investigator inserted a single sheet of VCF in the vagina of the volunteer at midcycle. The volunteer remained in the clinic and underwent vaginal lavage with normal saline after one of five specified time intervals had elapsed. The sequence of the intervals completed by each volunteer was determined by randomization. When undissolved film was found in the vagina, it was removed prior to lavage and assayed for N-9 content separately from that recovered in lavage fluid. It was assumed that the N-9 in undissolved film would not contribute significantly to sperm immobilization. Between 18.5 and 28.5 mg of N-9 were recovered in lavage fluid after intervals of 0.5, 1, 1.5, and 2 h. These levels did not differ statistically (p > 0.05). The amount of N-9 recovered dropped significantly at 4 h to 11.0 mg. If it is assumed that an N-9 concentration of 0.100 mg/mL is required to immobilize sperm in vitro, this study suggests that the amount of N-9 remaining in the vagina in the form of dissolved film up to 4 h after insertion of VCF is sufficient to immobilize sperm. The lavage procedure may not have recovered all N-9 remaining in the vagina. However, intercourse did not take place between insertion and lavage; if it had, the proportion of the film remaining undissolved and the total amount N-9 remaining in the vagina at the time of examination might have been affected.

PIP: The amount of nonoxynol-9 (N-9) remaining in the vagina 0.5, 1.0, 1.5, 2.0, and 4.0 hours after vaginal insertion of a single sheet of a contraceptive film (VCP) containing 70 mg of N-9 was investigated in a pharmacokinetic study involving 12 US women. At each of 5 test visits, approximately 1 month apart, a single sheet of VCF was inserted at midcycle. Vaginal lavage with normal saline was then performed after 1 of the 5 specified time intervals had elapsed. At 30 minutes, an average of 34.4 mg (49% of the total N-9) could be recovered. After intervals of 1.0, 1.5, and 2.0 hours, 18.5-28.5 mg of N-9 was recovered in lavage fluid. The amount of recovered N-9 dropped significantly to 11.0 mg after 4.0 hours. It is assumed that an N-9 concentration of 0.100 mg/mL is required to immobilize sperm. Thus, the amount of N-9 remaining in the vagina up to 4.0 hours after insertion of VCF is sufficient for contraception. The VCF label states that intercourse may take place 15 minutes after film insertion. Although lavage was not performed at this time point, it can be assumed that at least 49% of the original N-9 would be present. Since this study is limited by the fact that intercourse did not take place, future studies should include postcoital measures of the amount of N-9 persisting at various intervals.

Alteration of human sperm kinematics in cervical mucus due to nonoxynol-9.

Traditional endpoints of the double-ended test (DET), a contraceptive screening assay used to evaluate the ability of a compound to permeate cervical mucus and inhibit sperm progression, ignore important information about sublethal effects upon sperm cells. Improved contraceptive agents may capitalize on such sublethal aspects. This study utilized a DET testing protocol that included measurement of human sperm motion characteristics as an indicator of cell function within spermicide-exposed human mucus. The currently available spermicide nonoxynol-9 (N9) was used as the test compound and was dissolved in two different delivery solutions, deionized (DI) water and saline, to evaluate the effects of the osmolarity and pH of the delivery vehicle on test results. The N9-water treatment demonstrated significantly greater activity than the N9-saline treatment in terms of all measured variables, exhibiting an apparent "biopermeation" distance approximately 3 mm further into the mucus. The DI water control treatment displayed less activity than N9-saline in terms of the vanguard penetration distance, but comparable or greater activity in terms of inhibiting kinematic variables. The saline control treatment had no effect in terms of any measured variable. Dose responses to N9 of sperm in mucus were inferred from DET results combined with direct measures of N9 diffusion. These were compared to dose responses to N9 of seminal sperm, indicating that N9 inhibits sperm motion at lower concentrations in mucus than in semen.

PIP: The double-ended test (DET) generally used to assess the ability of new spermicidal compounds to permeate cervical mucus and inhibit sperm progression overlooks the importance of sublethal effects on sperm cells. This study utilized a DET protocol that incorporated measurement of human sperm motion characteristics as an indicator of cell function within nonoxynol-9-exposed human mucus. Nonoxynol-9 was dissolved in both deionized water and saline to assess the effects of the osmolarity and pH of the delivery vehicle. All variables exhibited significant effects due to the nonoxynol-9-water treatment at distances as far as 13 mm into the mucus. The water treatment exhibited a biopermeation distance approximately 3 mm further into the mucus than the saline treatment and greater activity in terms of inhibiting kinematic variables. On the other hand, penetration of vanguard sperm was inhibited more by nonoxynol-9-saline. The reduction in straightline velocity of sperm was due more to a disruption in the pattern of motion than a reduction in overall sperm vigor. The measurements of sperm motility obtained in this study can be combined with information about local nonoxynol-9 concentrations in mucus to infer the dose-response of nonoxynol-9 against sperm in mucus. Overall, these findings indicate that the use of hypotonic solutions to deliver contraceptive agents can significantly increase the efficacy of the compounds through both increased transport rates and added bioactivity due to the carrier itself.

Compatibility between the spermicide nonoxynol 9 and mid-cycle human cervical mucus.

The rate of diffusion of [125I]-nonoxynol 9 into mid-cycle human cervical mucus was measured and found to be negligible compared with D-glucose (used as an uncharged small molecule for comparison with nonoxynol 9). These data were confirmed by observation of the lack of inhibition of the movement of spermatozoa in mucus that had been in surface contact, for 3 hours, with a concentration 30 times greater than the ED100 of nonoxynol 9. These results show that the entry of nonoxynol 9 into mucus could be minimal under conditions that would exist in vivo and highlights a limitation of this compound as a vaginal contraceptive.

PIP: Obstetrician-gynecologists and chemists analyzed data on midcycle cervical mucus samples from normally cycling women attending the infertility clinic at the University Hospital of South Manchester, England, to determine the ability of nonoxynol-9 to diffuse into the mucus, thereby testing its spermicidal activity. They used the double diffusion test. They compared diffusion depths of radiolabelled nonoxynol-9 at 120 minutes with those of D-glucose, an uncharged small molecule. They compared the depths of these 2 methods with those of controls containing Tyrode's solution. Migration of spermatozoa in 6 nonoxynol-9 rectangular capillaries was greater than the Tyrode controls, lower in 5 capillaries, and the same in 9 capillaries. Thus, no difference in spermatozoal penetration into midcycle cervical mucus existed between nonoxynol-9 and Tyrode's solution. Further, a 62% concentration of D-glucose was evident in the 1st 5 mm of the cervical mucus column at 2 hours and the concentration fell exponentially. The chemists cold still detect D-glucose at 30 mm at 2 hours. On the other hand, they detected nonoxynol-9 at a 6 times lower concentration than D-glucose in the 1st 5 mm at 2 hours, but could not detect it beyond 5 mm. This meant that, in vivo, only 10% of nonoxynol-9 would be in the interfacial zone of the cervical mucus and not at greater depths. If these results hold true, the ability of nonoxynol-9 to act as a contraceptive and a means to destroy HIV would be limited in the upper genital tract and the cervix. In conclusion, nonoxynol-9's spermicidal activity in midcycle cervical mucus is considerably lower than it is in free solution.