Water-in-Oil Microemulsions Containing Medium-chain Fatty Acids/Salts: Formulation and Intestinal Absorption Enhancement Evaluation

Purpose. Water-in-oil (w/o) microemulsions have been developed which, in addition to non-ionic medium-chain glycerides, incorporate ionic lipids, primarily medium-chain fatty acids, such as caprylic (C₈) capric (C₁₀) and lauric (C₁₂) acids and their corresponding sodium salts. The absorption enhancing activity of w/o microemulsions incorporating these lipids was evaluated in the rat using Calcein (MW = 623) a water-soluble and poorly absorbed marker molecule. Methods. Phase diagrams were constructed where C₈/C₁₀ or C₁₂ fatty acids were treated as lipophilic surfactants and their sodium salts as hydrophilic ones. The anesthetised rat model was employed to evaluate Calcein absorption upon a single intraduodenal administration from a solution and the various w/o microemulsions. Results. A wide range of clear and transparent w/o microemulsions were obtained at ambient temperature either in liquid or solid form when a fixed blend of medium chain fatty acid/salt was titrated by a fixed ratio of the oil containing the oil-soluble mono- and diglycerides and deionized water or physiological saline. Upon intraduodenal administration in the anesthetised rat, the absorption of Calcein was improved from about 2% in aqueous solution up to about 37% in w/o microemulsions. Solid and liquid formulations were equally effective in improving bioavailability. The absorption enhancement activity of the fatty acids/salts followed the order C₈ C₁₀ > C₁₂. Absorption enhancement of Calcein was significantly reduced in the absence or presence of low levels of C₈/C₁₀ mono-/diglycerides. Conclusions. These results further support the use of medium-chain glycerides and fatty acids/salts in microemulsion formulations to improve intestinal absorption of water-soluble compounds.     

Evaluation of subchronic (13-week) and reproductive toxicity potential of intravaginal gel-microemulsion formulation of a dual-function phenyl phosphate derivative of bromo-methoxy zidovudine (compound whi-07) in B(6)C(3)F(1) mice

Heterosexual transmission of human immunodeficiency virus (HIV) accounts for 90% of all new infections worldwide and significantly contributes to new acquired immunodeficiency syndrome (AIDS) cases in the USA. In a systematic effort to develop a microbicidal contraceptive capable of preventing HIV transmission as well as providing fertility control, we previously identified novel phenyl phosphate derivatives of 3'-azido-3'-deoxythymidine (zidovudine) that exhibit potent anti-HIV and spermicidal activities. This study reports the preclinical studies of our lead compound WHI-07, 5-bromo-6-methoxy-5,6-dihydro-3'-azidothymidine-5'-(p-bromophenyl) methoxyalaninyl phosphate, for use as a dual-function topical microbicide. In vivo toxicity studies in non-human primates and rodents given WHI-07 (20 mg kg(-1)) intravenously and intraperitonealy, respectively, had no detectable adverse effects on hematological and clinical chemistry profiles. The 13-week subchronic and reproductive toxicity potential of an intravaginal gel-microemulsion formulation of WHI-07 was studied in mice to support its further development as a dual-function microbicide. Groups of ten female B(6)C(3)F(1) mice were exposed intravaginally to a gel-microemulsion formulation containing 0, 0.5, 1.0 or 2.0% WHI-07, 5 days a week, for 13 consecutive weeks. On a molar basis, these concentrations represent 1400-5700 times their in vitro spermicidal potency EC(50)) and 1.4 x 10(6)-5.7 x 10(6) times their in vitro anti-HIV activity(50)). After 13 weeks of intravaginal treatment, half of the treated mice were evaluated for toxicity and the other half were mated with untreated males to evaluate potential reproductive and developmental effects. The endpoints that were evaluated included survival, body weight gain, hematological and clinical chemistries, absolute and relative organ weights and histopathology. The WHI-07 applications did not cause weight loss, morbidity, mortality or specific tissue lesions detectable by histopathology. Repeated intravaginal exposure of mice to WHI-05 for 13 weeks had no adverse effects on subsequent reproductive performance (100% fertile), neonatal survival (>95%) or pup development. These findings collectively show that the experimental dual-function anti-HIV and contraceptive agent WHI-07 did not cause significant acute or subchronic toxicity.     

Effect of Tetrandrine on Morphine Induced Hyperactivity and Reinforcement in Mice

Ｏｂｊｅｃｔｉｖｅ：Ｔｏｓｔｕｄｙｔｈｅｅｆｆｅｃｔｏｆｔｅｔｒａｎ ｄｒｉｎｅｏｎｍｏｒｐｈｉｎｅｉｎｄｕｃｅｄｈｙｐｅｒａｃｔｉｖｉｔｙａｎｄｒｅｉｎｆｏｒｃｅｍｅｎｔｉｎｍｉｃｅ．Ｍｅｔｈｏｄｓ：Ａｆｔｅｒｓｉｎｇｌｅａｄｍｉｎｉｓｔｒａｔｉｏｎｏｆｍｏｒｐｈｉｎｅａｎｄｔｈｅｍｏｔｉｏｎａｃ ｔｉｖｉｔｙｗａｓｍｅａｓｕｒｅｄｂｙａｍｂｕｌｏｍｅｔｅｒ，ｃｏｎｄｉ ｔｉｏｎｅｄｐｌａｃｅ ｐｒｅｆｅｒｅｎｃｅｐａｒａｄｉｇｍｗａｓｕｓｅｄｔｏｓｔｕｄｙｔｈｅｒｅｉｎｆｏｒｃｉｎｇｅｆｆｅｃｔ…     

Contraceptive efficacy and safety studies of a novel microemulsion-based lipophilic vaginal spermicide

OBJECTIVE: To investigate the in vivo contraceptive potency and safety of a novel microemulsion-based lipophilic vaginal spermicide. DESIGN: In vitro and in vivo spermicidal activity and safety of a submicron-particle-size, lipophilic gel-microemulsion (GM-4). SETTING: Center for Advanced Preclinical Sciences at the Parker Hughes Institute. PATIENT(S): Nine male volunteer sperm donors. INTERVENTION(S): Motile human sperm in semen and medium were exposed to eight GM-4 components or GM-4 formulation. Forty-eight ovulated NZW rabbits in subgroups of 16 with or without intravaginal administration of GM-4 or nonoxynol-9 gel (N-9; Gynol II) were artificially inseminated and allowed to complete pregnancy. Eleven rabbits were exposed to daily intravaginal application of GM-4 with and without N-9 for 10 consecutive days. Ten of 20 B(6)C(3)F(1) mice were given repetitive intravaginal application of GM-4 for 5 days/week over 13 consecutive weeks. MAIN OUTCOME MEASURE(S): The motility of human sperm treated with GM-4 components and GM-4. Term pregnancy in rabbits and histopathological grading of rabbit vaginal tissue for irritation. Evaluation of mice for survival, growth, hematologic parameters, blood-chemistry profiles, absolute and relative organ weights, and histopathology. RESULT(S): The individual components of GM-4 lacked spermicidal activity in human semen, whereas the GM-4 formulation containing all the eight pharmacological excipients exhibited potent spermicidal activity with rapid kinetics. GM-4 showed remarkable contraceptive activity in the rigorous rabbit model. None of the 16 (0%) rabbits given GM-4 intravaginally before artificial insemination became pregnant. By contrast, 15 of 16 (93.7%) control rabbits and 5 of 16 (31.2%) Gynol II-treated rabbits became pregnant and delivered newborns. Thus, GM-4 was a significantly more effective contraceptive than a commercially available N-9 gel [100% vs. 68.7% protection; P< 0.05, Fisher's exact test]. Unlike the rabbits treated with N-9, none of the rabbits that were given GM-4 intravaginally for 10 consecutive days developed epithelial ulceration, edema, leukocyte influx, or vascular congestion characteristic of inflammation. Furthermore, repeated intravaginal application of GM-4 for up to 13 weeks in mice had no adverse effects on survival, growth, metabolism, or organ function. CONCLUSION: We conclude that the novel spermicidal GM-4 formulation is safe and significantly more effective than N-9 in preventing conception.     

Evaluation of subchronic (13 weeks) and reproductive toxicity potential of intravaginal gel-microemulsion formulation of a dual-function phenyl phosphate derivative of bromo-methoxy zidovudine (compound WHI-05) in B(6)C(3)F(1) mice

Heterosexual transmission of human immunodeficiency virus (HIV) accounts for 90% of all new infections worldwide and significantly contributes to new acquired immunodeficiency syndrome (AIDS) cases in the United States. In a systematic effort to develop a microbicidal contraceptive capable of preventing HIV transmission as well as providing fertility control, we previously identified novel phenyl phosphate derivatives of 3'-azido-3'-deoxythymidine (zidovudine) which exhibit potent anti-HIV and spermicidal activities. This study reports the preliminary preclinical study of our lead compound WHI-05, 5-bromo-6-methoxy-5, 6-dihydro-3'-azidothymidine-5'-(p-methoxyphenyl) methoxyalaninyl phosphate, for use as a dual-function topical microbicide. Acute toxicity studies have shown that WHI-05 has no detectable adverse effects on laboratory animals. The 13-week subchronic and reproductive toxicity potential of intravaginal gel-microemulsion formulation of WHI-05 were studied in mice to support its further development as a virucidal spermicide. Groups of 10 female B(6)C(3)F(1) mice were exposed intravaginally to a gel-microemulsion formulation containing 0%, 0.5%, 1.0%, or 2.0% WHI-05, 5 days/week for 13 consecutive weeks. On a molar basis, these concentrations represent 300 to 1200 times their in vitro spermicidal potency, and 1.5x10(4) to 6.1x 10(4) times their in vitro anti-HIV activity. After 13 weeks of intravaginal treatment, one half of treated mice were evaluated for toxicity, and the other half were mated with untreated males to evaluate potential reproductive and developmental effects. Repetitive intravaginal application of WHI-05 to yield a local concentration 6.1x10(4) times higher than its in vitro HIV IC(50) value and 1200 times higher than its spermicidal EC(50)96%), or pup development. These findings collectively show that the experimental dual-function anti-HIV and contraceptive agent, WHI-05, did not cause significant acute or subchronic and reproductive toxicity under the test conditions.