Chemical structure of azithromycin.
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Azithromycin is the first macrolide antibiotic belonging to the azalide group. Azithromycin is derived from erythromycin by adding a nitrogen atom into the lactone ring of erythromycin A, thus making the lactone ring 15-membered. Azithromycin is sold under the brand names Zithromax and Sumamed, and is one of the world's best-selling antibiotics. Azithromycin is used for the treatment of respiratory-tract, soft-tissue and genitourinary infections. more...

Zoledronic acid


Azithromycin's name is derived from the azane-substituent and erythromycin. Its accurate chemical name is

(2R,3S,4R,5R,8R,10R,11R,12S,13S,14R)-13- -2-ethyl- 3,4,10-trihydroxy-3,5,6,8,10,12,14-heptamethyl -11--1-oxa- 6-azacyclopentadecan-15-one.


A team of Pliva's researchers, Gabrijela Kobrehel, Gorjana Radobolja-Lazarevski and Zrinka Tamburasev led by Dr Slobodan Dokic, discovered azithromycin in 1980. It was patented in 1981, and was later found by Pfizer's scientists while going through patent documents. In 1986 Pliva and Pfizer signed a licensing agreement which gave Pfizer exclusive rights for the sale of azithromycin in Western Europe and the United States. Pliva brought their azithromycin on the market in Central and Eastern Europe under the brand name of Sumamed in 1988, and Pfizer Zithromax in 1991.

Available forms

Azithromycin is commonly administered in tablet or oral suspension. It is also available for intravenous injection.

Mechanism of action

Azithromycin prevents bacteria from growing by interfering with their protein synthesis. Azithromycin binds to the 50S subunit of the bacterial ribosome, and thus inhibits translation of mRNA. Azithromycin has similar antimicrobial spectrum as erythromycin, but is more effective against certain gram-negative bacteria, particularly Hemophilus influenzae.


Unlike erythromycin, azithromycin is acid-stable and can therefore be taken orally without being protected from gastric acids. It is readily absorbed, and diffused into most tissues and phagocytes. Due to the high concentration in phagocytes, azithromycin is actively transported to the site of infection. During active phagocytosis, large concentrations of azithromycin are released. The concentration of azithromycin in the tissues can be over 50 times higher than in plasma. This is due to ion trapping and the high lipid solubility.


Azithromycin's half-life is approximately 2 days, and it's fairly resistant to metabolic inactivation. Its main elimination route is through excretion in the biliary fluid, and some can also be eliminated through urinary excretion. Azithromycin is excreted through both of these elimination routes mainly in unchanged form.

Side effects

Most common side effects are gastrointestinal; diarrhea, nausea, abdominal pain and vomiting.


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Protect your fertility: what you can do now to safeguard your chances of motherhood later - Reproductive Health
From Shape, 9/1/03 by Lisa Lombardi

Have you noticed? All it takes to ruin a good night out or turn a book group into a heated debate are two words: biological clock For us women, that term is one of the most hated, feared and loaded in the English language.

The media messages we receive only serve to exacerbate our distress. In the fall of 2001, for instance, the American Society for Reproductive Medicine rolled out a public-service campaign reminding women that "advancing age decreases your ability to have children." (The text was accompanied by the image of an hourglass shaped like a baby bottle.)

While age is a vital factor in your ability to conceive, it's not the only one. "There are proactive, effective measures that you can start applying now to help preserve your fertility down the road," says Nanette R Santoro, M.D., director of the division of reproductive endocrinology and infertility at Albert Einstein College of Medicine of Yeshiva University and Montefiore Medical Center in New York City. To start taking charge of your future fertility today, follow this advice.

1. Reduce your risk for STDs.

"One of the most important things you can do for your fertility is to prevent STDs (sexually transmitted diseases), such as chlamydia, gonorrhea, syphilis, herpes and human papillomavirus (HPV). These infections can lead to scarring of your fallopian tubes and cause precancerous changes of the cervix," says Sheryl A. Ross, M.D., an OB/GYN and fertility specialist in private practice in Santa Monica, Calif.

There are two equally important steps to reducing your risk for STDs. First, practice safe sex, meaning always use condoms if you aren't in a long-term monogamous relationship. Second, if you're sexually active, ask your OB/GYN for annual screenings for STDs, says Lorraine Chrisomalis, M.D., assistant clinical professor of obstetrics in the division of Maternal Fetal Medicine at Columbia Presbyterian Eastside in New York City. (Note that a Pap test doesn't screen for STDs.)

While you'd probably know if you had syphilis (symptoms may include a painless genital lesion, swollen lymph nodes and fever) or gonorrhea (symptoms include yellowish-green vaginal discharge and painful urination), chlamydia and HPV could catch you unaware. "Chlamydia is very insidious, because it's common to have it without presenting any symptoms," Chrisomalls says. HPV--the most common viral STD--is also often silent: While some women with HPV develop genital warts, the majority of infected women show no sign of the virus.

If your OB/GYN detects chlamydia, it can be treated easily with an antibiotic such as Zithromax. (Make sure your partner also gets treated; otherwise he could give the infection right back to you.) Preventing HPV is difficult, since no form of barrier contraception is completely protective. Untreated, some strains of the virus can cause abnormal cervical-cell changes (which can be detected by a Pap smear) that could require you to undergo a cervical cone biopsy, a surgical procedure that involves removing a cone-shaped slice of your cervix to test for cancer. This procedure can shorten your cervix, leading to problems holding on to a pregnancy, Chrisomalis says.

2. Monitor your menstrual cycle.

If you're having unusual periods--for example, the length of your cycle or the amount of bleeding or cramping has changed--inform your OB/GYN, because you could have a condition, from a temporary, stress-related decrease in the production of eggs to perimenopause, that's affecting your fertility. "It's important to bring up any changes to your cycle before you're ready to get pregnant," Santoro says. If every month you've had slightly shorter or longer than the average 28-day cycle, that's nothing to worry about. But if you have really irregular periods--meaning you get your period one month, then don't get it again for two or three months, or you get it twice in one month--you should get checked out, Santoro says. Not only do erratic periods make it hard to pinpoint when you're ovulating (which is necessary when you're trying to conceive), they also may be a sign that you're not ovulating, which requires further investigation and possibly treatment.

In addition, tell your doctor if your period is suddenly much heavier or lighter. "Unusually heavy and painful periods could be a sign of fibroids, polycystic ovary syndrome or endometriosis," Chrisomalis says. All three are treatable, she says, but since the medication (birth-control pills or Lupron) temporarily stops ovulation, it's best to seek treatment before you're thinking about getting pregnant.

3. Maintain a healthy weight.

By now you know how unhealthy it is to be seriously overweight. But you may not be aware of the extent to which it can impair your ability to conceive: "Several studies have shown that women who are obese and less fit have a harder time getting pregnant," Santoro says.

But being too thin may pose just as much or even more of a problem. "Women who have below-normal body fat may lose their period and have trouble getting pregnant or hanging on to a pregnancy," Santoro says. The culprit: low estrogen, which prevents underweight women from ovulating.

But even if you're still getting your period, you could be what experts call subfertile: not quite infertile but less fertile than ideal. "The research shows that when thin women who can't get pregnant gain 6 or 8 pounds, they often become pregnant right away," says Alice Domar, Ph.D., co-author of Conquering Infertility: Dr. Alice Domar's Mind/Body Guide to Enhancing Fertility and Coping With Infertility (Viking, 2002).

However, women with a history of eating disorders remain more likely to have trouble conceiving; some are infertile due to diminished estrogen levels. "I have a 31-year-old patient who has an estrogen level consistent with a menopausal woman," Ross says.

4. Tune in to your mood.

Researchers have long suspected that high stress levels impair fertility. And while some studies have confirmed this, it's depression--rather than anxiety--that seems to affect fertility most. "Women who have been depressed are twice as likely as the general population to have a subsequent problem with infertility," Domar says. "Researchers don't know why, but they do know that depressed women release less luteinizing hormone, which is important for ovulation."

If you suspect you may be depressed (you've been experiencing any or all of the following symptoms for two weeks or more: difficulty sleeping, poor or increased appetite, feelings of hopelessness and losing interest in activities you usually enjoy), talk to your doctor about getting help now. "Make sure your depression is under control before you're ready to conceive," Domar says. Treating depression successfully can take time, especially if your doctor prescribes an antidepressant. And once you do start trying, if you're over 35 and haven't gotten pregnant after six months of unprotected intercourse, consult a fertility specialist; if you're under 35, consult one after a year of trying.

5. Quit smoking.

How's this for scary news: "A number of different studies have shown that smoking reduces fertility and actually speeds up your biological clock. On average, smokers hit menopause two years earlier than nonsmokers," Santoro says. That means some smokers start getting hot flashes and other menopausal symptoms even earlier.

In addition, smoking puts you at greater risk for having a tubal (ectopic) pregnancy, which is not a viable pregnancy and can threaten your life. If undiagnosed, an ectopic pregnancy can rupture your fallopian tube, making you less fertile.

6. Don't wait too long.

As you've already suspected, the fact is: Age is the No. 1 factor when it comes to infertility. In the uterus, a baby girl has the most eggs she'll ever have in her life; as soon as she's born the number starts diminishing. "The design is poor--you have an excellent number of eggs when you don't need them," Chrisomalis says. "And not only do you have fewer eggs as you age, but the quality of the eggs you're left with isn't as good."

While fertility starts declining in a woman's late 20s, experts say that most women don't encounter real age-related fertility problems before their mid-30s; if they do, they usually can get pregnant with treatment. After age 35, fertility takes a marked decline. A 30-year-old woman has about a 20 percent chance per month to get pregnant. By age 40, however, she has only about a 5 percent chance per month.

The risk of miscarriage also increases with age: 10 percent for women in their 20s, compared with 18 percent for women ages 35-39, 34 percent for women 40-44, and 53 percent for women 45 and older. While you can't stop the clock, you can control your risk for STDs, your weight and the other factors cited above. You'll help protect not only your chances of conceiving, but your health for life.

fertility resources

Hoping to have a baby one day? Having trouble conceiving right now? The following resources will help answer your questions about conception:

* Conquering Infertility: Dr. Alice Domar's Mind/Body Guide to Enhancing Fertility and Coping With Infertility by Alice D. Domar, Ph.D., and Alice Lesch Kelly (Viking, 2002): an insightful and empowering exploration of the mind-body role in conception

* The American Society for Reproductive Medicine's Web site ( Bookmark this site to stay up on the latest fertility research and locate an ASRM-member physician or infertility clinic in your area.

star moms over 40

These famous females all had babies in their 40s. The question on everyone's mind is: Did they have help conceiving? Only a few have discussed it publicly.

1. Emma Thompson At 40, the Brit thespian and her partner, actor Greg Wise, welcomed their first child, a girl named Gaia.

2. Julianne Moore gave birth to her second child, a daughter named Liv, with fiance Bart Freundlich when she was 41.

3. Madonna was five days short of 42 when she had her second baby, Rocco, her first child with her English director-hubby Guy Ritchie.

4. Christie Brinkley The former supermodel sought in vitro fertilization treatment and had three miscarriages before giving birth at 44 to her third child, daughter Sailor Lee, with husband Peter Cook.

5. Iman At 45, the model/actress wife of David Bowie gave birth to their daughter, Alexandria Zahra.

6. Susan Sarandon had her son Miles, her third child (and second with live-in love Tim Robbins), at 45.

7. Geena Davis Married four times, the Oscar winner was 46 when she delivered her first child, a girl named Alizeh Keshvar, with husband Reza Jarrahyo.

Lisa Lombardi is a health writer in Los Angeles.

COPYRIGHT 2003 Weider Publications
COPYRIGHT 2003 Gale Group

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