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Biomedical subjects

N N Sarkar

Publications and source records attributed to N N Sarkar.

17 recordsLinked to original sources
PubMed2005

The combined contraceptive vaginal device (NuvaRing): a comprehensive review.

OBJECTIVES: The aim of this study is to review the development of NuvaRing over the past decade to illustrate its use-effectiveness and acceptance as an alternative contraceptive option for women. METHODS: The data were extracted from the literature using computerised MEDLINE system. NuvaRing is a new combined hormonal contraceptive vaginal ring made of ethylene-vinyl-acetate copolymer, releasing 120 microg etonorgestrel and 15 microg ethinyloestradiol per day. This ring is inserted on any day from day 1 to day 5 of a menstrual cycle for 21 days, thereafter removed for 7 days ring-free period and discarded. RESULTS: Complete inhibition of ovulation is observed during treatment with this device. Clinical exposure to NuvaRing for 1786 women-years has resulted in 21 pregnancies, giving a Pearl Index of 1.18. Withdrawal bleeding (4.7-5.3 days) is regular (97-99% of cycles) with rare incidence of irregular bleeding (2.6-6.4%). The cycle control is good with the use of this combined contraceptive vaginal ring. NuvaRing is well tolerated and accepted by women as compared to oral pill. CONCLUSIONS: NuvaRing is an effective vaginal contraceptive option for women. However, further study is needed for monitoring its long-term effectiveness and impact on patient's quality of life since the NuvaRing is marketed in many countries.

Adult↗
PubMed2005

The potential of mifepristone (RU-486) as an emergency contraceptive drug.

The potential of mifepristone to be an emergency contraceptive is reviewed. Mifepristone prevents 92-100% of pregnancies with an acceptable side-effect profile on oral intake of a 10-600-mg dose within 72 h of unprotected intercourse. A single dose of 10 mg mifepristone resulted in a pregnancy rate of 1.5%, similar to a 1.5-mg single dose or two doses of 0.75 mg levonorgestrel 12 h apart, administered within 120 h (current standard) of unprotected sexual intercourse. Mifepristone and levonorgestrel do not differ in efficacy as emergency contraceptives. The mode of action of emergency contraception (EC) with mifepristone or levonorgestrel is primarily associated with inhibition of ovulation rather than prevention of implantation. Different doses of mifepristone appear to have similar effects. However, delay in the onset of subsequent menstruation caused by mifepristone is dose dependent and is reduced with a lower dose without affecting its efficacy. Patient acceptability of mifepristone as EC is high. However, the optimum standard dose of mifepristone is yet to be established for its application as an effective and acceptable emergency contraceptive drug for ordinary clinical use or practice.

Contraceptives, Postcoital, Synthetic↗
PubMed2003

Steroidal contraceptive vaginal rings.

The development of steroid-releasing vaginal rings over the past three decades is reviewed to illustrate the role of this device as an effective hormonal contraceptive for women. Vaginal rings are made of polysiloxane rubber or ethylene-vinyl-acetate copolymer with an outer diameter of 54-60 mm and a cross-sectional diameter of 4-9.5 mm and contain progestogen only or a combination of progestogen and oestrogen. The soft flexible combined ring is inserted in the vagina for three weeks and removed for seven days to allow withdrawal bleeding. Progesterone/progestogen-only rings are kept in for varying periods and replaced without a ring-free period. Rings are in various stages of research and development but a few, such as NuvaRing, have reached the market in some countries. Women find this method easy to use, effective, well tolerated and acceptable with no serious side-effects. Though the contraceptive efficacy of these vaginal rings is high, acceptability is yet to be established.

Contraceptive Devices, Female↗
PubMed2003

Levonorgestrel as an emergency contraceptive drug.

The potential of low-dose levonorgestrel, alone or in combination with ethynyloestradiol (Yuzpe regimen), as emergency contraception is reviewed for its acceptability and effectiveness. Plasma levonorgestrel concentration ranges from 9-12 nmol/l at 12 hours with a peak of 27-33 nmol/l 2-2.5 hours after taking one 0.75 mg tablet. The concentration of steroid hormone binding globulins in plasma is not influenced by the presence of levonorgestrel during this period. The success rates for levonorgestrel-only and the Yuzpe regimen as emergency contraception are 85% and 57%, respectively, while the failure rates are 1.1% and 3.2%, respectively, within the prescribed time limit of use. The mode of action of levonorgestrel emergency contraception is to prevent or delay ovulation and/or alter the endometrium unfavourably the for implantation of an embryo. The use of emergency contraceptive pills within 72 hours after unprotected sexual intercourse reduces the risk of pregnancy by about 75% and is safe, with no serious side-effects.

Adolescent↗
PubMed2003

Low-dose intravaginal estradiol delivery using a Silastic vaginal ring for estrogen replacement therapy in postmenopausal women: a review.

OBJECTIVES: The aim of this study was to review the potential of the intravaginal ring to be an effective low-dose estrogen delivery system for the treatment of postmenopausal women. METHODS: The data were extracted from the literature using the computerized MEDLINE system. The soft and flexible ring (Estring(R)) is made of silicone rubber with a 55-mm outer diameter and 9.5-mm cross-sectional diameter, contains 2 mg 17beta-estradiol in the core section with the release specification limit of 6.5-9.5 microg/24 h and maintains a continuous plasma estradiol concentration of 20-30 pmol/l for 3 months when inserted in women. RESULTS: Comparative clinical trials have demonstrated that treatment with the intravaginal ring is excellent at alleviating subjective and objective symptoms of estrogen deficiency, restores vaginal mucosa, induces a high maturation index of mucosal cells and reduces vaginal pH to < 5.5 in postmenopausal women. No major side-effects or endometrial proliferation have been observed during treatment. The majority of patients prefer using the vaginal ring to other currently available vaginal steroid delivery systems. The sustained low-dose estrogen therapy is also found to improve the serum lipid profile in elderly women. CONCLUSIONS: It is suggested that the low-dose estradiol intravaginal ring is safe, effective and well accepted for the treatment of estrogen deficiency symptoms in postmenopausal women.

Aged↗
PubMed2002

Mifepristone: bioavailability, pharmacokinetics and use-effectiveness.

The potentiality of mifepristone as an abortifacient and contraceptive drug along with its pharmacokinetic parameters is reviewed. Mifepristone or RU486 acts as antagonist to progestational and glucocorticoid functions. It is an orally active compound with nearly 70% absorption rate but its bioavailability is reduced to around 40% because of the first-pass effect. Peak plasma concentrations of 1.9 +/- 0.8, 3.8 +/- 0.9 and 5.3 +/- 1.3 micromol/l are reached within 1-2 h after oral administration of 50, 200 and 600 mg mifepristone in women, respectively, and are maintained at relatively high level up to 48 or 72 h depending on the ingested dose. The plasma kinetics of mifepristone followed two-compartment open model with a mean alpha-half-life of 1.4h, volume of distribution 1.47 l/kg and beta-half-life of 20-30 h in most of the subjects studied. Clearance from the body was mainly through feces (83%). Biologically active mono-demethylated, di-demethylated and hydroxylated metabolites were found in plasma soon after oral administration of mifepristone. RU486 and its mono-demethylated metabolite bind to progesterone receptors with high affinity. Mifepristone-bound receptor dimers suppress transcription activation and thus, bring about anti-progestational activity that makes mifepristone a potential abortifacient and contraceptive agent. Clinical trials for termination of early pregnancy with 50-600 mg mifepristone plus a prostaglandin analogue achieved a success rate of 82-97%. However, abdominal pain, cramping, nausea, vomiting, bleeding and delay in onset of the next menstrual cycle were the side effects. Administration of 25 mg mifepristone twice 12h apart, as a post-coital contraceptive showed 100% contraceptive efficacy. A low dose of mifepristone which does not inhibit ovulation reduced fertility significantly by affecting endometrial milieu. These findings suggest that reduced dose(s) of mifepristone, 200 mg or less, may be used as a post-coital contraceptive and in combination with vaginal misoprostol for termination of early pregnancy with high efficacy and minimal or no side effects.

Abortifacient Agents, Steroidal↗
PubMed2002

The potential of mifepristone (RU486) as a female contraceptive drug.

This article reviews the development of mifepristone (RU486) as a female contraceptive drug. Mifepristone is an orally active compound with nearly 40% bioavailability after first pass effect. The steady plasma level of mifepristone ranges from 65 nmol/l with 1 mg/day to 1 micromol/l with 10 mg/day and reaches 2.5 micromol/l, 4.5 micromol/l and 5.4 micromol/l with mifepristone 50 mg, 100 mg and 200 mg daily, respectively, over the treatment period. Inhibition of ovulation may be achieved at serum mifepristone concentration of 232.7 nmol/l. Mifepristone appears to antagonise progesterone at the pituitary level to suppress gonadotropin and steroid hormone secretion rather than to act primarily on the hypothalamus to delay or inhibit ovulation. In fact, the endometrium is most sensitive to mifepristone. Low-dose mifepristone impairs luteal phase endometrial development and receptivity by altering endometrial parakine, cytokine and enzyme activity. Thus, low-dose mifepristone can significantly reduce the rate of conception without inhibiting ovulation. However, further research is needed to standardise the dose and dose-schedule to achieve the desired efficacy of low-dose mifepristone for routine clinical use with minimal or no side-effects.

Clinical Trials, Phase I as Topic↗
PubMed2000

Steroidal contraception for men.

This article is a review of the development of male steroidal contraceptives during the past 25 years. Numerous studies have been conducted on male volunteers with oral and/or injectable preparations of single or combined steroids. Progestogen, androgen alone, or progestogen and androgen combinations have been used as weekly or monthly injectable formulations. Most of the studies involved small numbers of subjects. There was reversible suppression of spermatogenesis to oligospermia and/or azoospermia during the treatment period. Alteration of LH, FSH and testosterone levels in the blood was observed in most of these studies, depending on the steroid or combination of steroids used. There were reports about decreased or increased libido and weight gain during treatment with steroids. No other serious side-effects were found. Attention has recently focused on developing an androgen-only male contraceptive, because testosterone ester has shown promising results. The development of an effective and reliable steroidal contraceptive for men may be possible but this requires further research.

Androgens↗
PubMed1993

Sterilisation: characteristics of vasectomy acceptors in Delhi.

The place of vasectomy within the sterilisation programme in Delhi over the period 1983-88 is reviewed and data on vasectomy acceptance and characteristics of acceptors are analysed. Findings suggest a need to improve the strategy for the promotion of vasectomy within the metropolis.

Adolescent↗
PubMed1990

Psycho-social factors influencing decisions to accept termination of pregnancy in Delhi.

"Among women attending the MTP [medical termination of pregnancy] clinic of the National Institute of Health and Family Welfare, New Delhi [India], during 1985-86, 135 were interviewed to ascertain the psychosocial factors indluencing their decision to accept MTP. These women's decisions to seek MTP appear to have been influenced by education, number of living children, and the family's socioeconomic condition."

Abortion, Induced↗
PubMed1983

Norethindrone in serum after use of an oral contraceptive containing norethindrone acetate.

The availability of norethindrone (NET) in serum was studied in 8 women after daily administration of a combination oral contraceptive pill (MinovlarR) containing 1 mg norethindrone acetate (NETA) and 50 micrograms ethinyl estradiol (EE2) from day 5 to day 25 of the menstrual cycle. The pill was taken daily at 9:30 a.m. after a light breakfast and blood samples were collected at 3 hr on alternate days and at 24 hr on other days after ingestion of the pill. On day 12 or day 15 of the first treatment cycle, serial blood samples were also collected at 1/2, 1, 2, 4, 6, 8 and 24 hr after taking the pill. Serum NET levels were estimated by the radioimmunoassay (RIA) technique. The plot of serum NET concentration versus time (0-24 hr) profile showed a rapid absorption of steroid and a peak NET concentration (18.3 +/- 4.8 ng/ml) reached at 2 hr after ingestion of the pill. By linear regression analysis of data (y = 0.27 + 0.12x; r = 0.95), it was observed that the serum NET level was initially about 1 ng/ml. Thereafter, it increased by 0.12 ng/ml per day up to 3.5 ng/ml by the end of 21 days' treatment with oral pills. The serum NET concentration decay slope fitted a two-compartment open model with an initial rapid decay (half-life of 1.2 +/- 0.1 hr) followed by a slower beta-phase with a half-life of 8.5 +/- 1.5 hr. The study revealed that there was an accumulation of norethindrone in plasma during the treatment period and this suggests the possibility of exploring a reduction in the dose of this preparation so as to achieve the optimum NET concentration for contraception, and thereby avoiding unwanted steroid accumulation in the plasma of women.

Adult↗
PubMed1981

Correlation between the serum norethindrone (NET) levels attained after insertion of a silastic implant releasing norethindrone acetate and the endogenous hormones particularly progesterone.

Six normally menstruating women were inserted each with a single silastic implant-D releasing norethindrone acetate (NETA). The levels of endogenous hormones, FSH, LH, E2 and progesterone, were estimated by radioimmunoassay (RIA) procedures in the control and treatment cycles. In addition, the levels of drug in the serum as norethindrone (NET) which is a major metabolite of NETA were also estimated by RIA procedures in the treatment cycles. In all, 12 treatment cycles were studied. In the initial treatment cycles (1st/2nd or 3rd), the serum NET levels were either 1 ng/ml or above. The LH and FSH showed either normal or suppressed mid-cycle peaks, but the progesterone levels were completely suppressed. In the sixth treatment cycles, the serum NET levels were either 0.5 ng/ml or below. The FSH and LH mid-cycle peaks were lower but distinct while the luteal progesterone levels were of normal ovulatory type. These studies lead us to the conclusion that a serum level of NET of the order of 1 ng/ml is required to bring about suppression of luteal progesterone, either as a result of direct action on the ovary or through suppression of pituitary gonadotropins. When the serum level falls to 0.5 ng/ml or below, the suppressive effect is removed and ovulatory pattern of progesterone returns.

Drug Implants↗
PubMed1980

Congenital hypoplasia of portions of both right and left ventricular myocardial walls. Clinical and necropsy observations in two patients with parchment heart syndrome.

Clinical and morphologic findings are described in two patients with congenital hypoplasia of portions of both right and left ventricular free walls in the absence of associated coronary or valvular heart disease. One, a 61 year old man who had never had clinical evidence of cardiac dysfunction, died suddenly and unexpectedly. The second, a 55 year old woman, died of progressive, eventually intractable congestive heart failure of 29 months' duration. Although at least 22 necropsy patients have previously been reported to have "parchment-like" thinning of portions of the right ventricular free wall, only one patient has previously been described with such thinning of portions of both right and left ventricular free walls. The spectrum of right or right and left ventricular wall congenital hypoplasia is a broad one, with nearly half of described patients dying of congestive heart failure in the 1st year of life and the other half reaching adulthood with or without manifestations of cardiac dysfunction.

Cardiomyopathies↗
PubMed1980

Bioavailability of norethindrone in rabbits after administration of norethindrone acetate in single, double and quadruple doses released through subcutaneous silastic implants.

Plasma level of norethindrone (NET) and in vivo release of norethindrone acetate (NETA) were studied in three groups of albino rabbits (5 animals/group) after insertion of one, two and four subcutaneous implants, each containing 40 mg crystalline NETA over a period of 24 weeks. The ratios of the in vivo release rate of steroid were 1, 1.9 and 3.9 in the animals of group I (one implant), group II (two implants) and group III (four implants) respectively. Thus, the in vivo release rate in group II and III showed an increase which was almost twice and four times as great as that of group I. However, the mean ratios of the serum NET levels were 1, 1.2 and 2.4 in animals of group I, II and III respectively. Thus, interestingly, the serum NET level did not show the expected twofold and fourfold increase and lacked correlation with the in vivo release. Although the insertion of multiple implants gives multiple increases in the in vivo steroid release, it does not give rise to a multiple increase in the serum levels of the steroid. It is possible that there is a kind of threshold of steroid concentration in the animals when they are loaded with exogenously administered steroid. When the steroid concentration tends to cross the threshold level, pharmacokinetic or pharmacodynamic processes of the animal work maximum to hold down the steroid level in blood plasma.

Animals↗
PubMedDate not supplied

Mercury in the environment: effect on health and reproduction.

Mercury is a heavy metal that is found naturally in the environment in various forms. Human activity can release mercury into the air, water, and soil. Mercury is also released into the environment after its conversion to methylmercury by bacteria. Mercury was once used in medicine, but the medicinal aspect changed because of its devastating poisoning effect on humans and animals. Today, mercury is one of the most potent neurotoxins known, having a number of adverse health effects in animals and humans. As the sources of mercury are many, the general population is exposed to mercury in day-to-day life, in occupational settings, and in cases of accidental exposure. In addition, ignorance about the use of mercury in cosmetics and religious materials has opened an additional source of exposure. Therefore, making people aware of mercury's effects on health, its sources of entry into the environment, and its chelating remedies becomes a necessity so that strategies can be adopted to minimize use and exposure.

Biotransformation↗
PubMedDate not supplied

Emergency contraception.

Emergency contraception means preventing pregnancy after unprotected sexual intercourse. This is also called postcoital contraception (PCC) or the 'morning-after pill'. High doses of oestrogen or progestogen or a combination of both may be used as PCC up to 72 hours after unprotected intercourse. The use of mifepristone as emergency contraception has also proved promising. Some women use emergency contraception, but there are many who do not know much about it. Users, providers and other health professionals need to be educated about this method. Emergency contraception does not fall within the ambit of abortion law, yet its acceptability depends on the legal, cultural and religious consideration of most countries. This method is safe and effective and could be used occasionally to prevent unwanted pregnancy.

Contraception↗