Ursodiol is used to dissolve gallstones in patients who do not want surgery or cannot have surgery to remove gallstones. Ursodiol is also used to prevent the formation of gallstones in overweight patients who are losing weight very quickly. Ursodiol is a bile acid, a substance naturally produced by the body that is stored in the gallbladder. It works by decreasing the production of cholesterol and by dissolving the cholesterol in bile so that it cannot form stones.

This medication is sometimes prescribed for other uses; ask your doctor or pharmacist for more information.

Uracil ( YOOR-a-sill) mustard belongs to the group of medicines known as alkylating agents. It is used to treat some kinds of cancer as well as some noncancerous conditions.

Uracil mustard interferes with the growth of cancer cells, which are eventually destroyed. Since the growth of normal body cells may also be affected by uracil mustard, other effects will also occur. Some of these may be serious and must be reported to your doctor. Other effects, such as hair loss, may not be serious but may cause concern. Some effects may not occur for months or years after the medicine is used.

Before you begin treatment with uracil mustard, you and your doctor should talk about the good this medicine will do as well as the risks of using it.

Uracil mustard is available only with your doctor's prescription, in the following dosage form:

Oral
• Capsules (U.S.)

Urofollitropin (yoor-oh-fol-li-TROE-pin ) is a fertility drug that is identical to the hormone called follicle-stimulating hormone (FSH) that is produced naturally by the pituitary gland.

FSH is primarily responsible for stimulating growth of the ovarian follicle, which includes the developing egg, the cells surrounding the egg that produce the hormones needed to support a pregnancy, and the fluid around the egg. As the ovarian follicle grows, an increasing amount of the hormone estrogen (ES-troe-jen) is produced by the cells in the follicle and released into the bloodstream. Estrogen causes the endometrium (lining of the uterus) to thicken before ovulation occurs. The higher blood levels of estrogen will also provide a cue to the hypothalamus and pituitary gland to slow the production and release of FSH.

Another pituitary hormone, luteinizing hormone (LH), also helps to increase the amount of estrogen produced by the follicle cells. However, the main function of LH is to cause ovulation. The sharp rise in the blood level of LH that triggers ovulation is sometimes called the LH surge. After ovulation, the group of hormone-producing follicle cells become what is called the corpus luteum and will produce estrogen and large amounts of another hormone, progesterone (proe-JES-ter-one) . Progesterone causes the endometrium to mature so that it can support the egg after it is fertilized. If implantation of a fertilized egg does not occur, the levels of estrogen and progesterone decrease, the endometrium sloughs off, and menstruation occurs.

Urofollitropin is usually given in combination with human chorionic gonadotropin (hCG). The actions of hCG are almost identical to those of LH. It is given to simulate the natural LH surge. This results in predictable ovulation.

Urofollitropin is often used in women who have low levels of FSH and too-high levels of LH. Women with polycystic ovary syndrome usually have hormone levels such as this and are treated with urofollitropin to make up for the low amounts of FSH. Many women being treated with urofollitropin have already tried clomiphene (e.g., Serophene) and have not been able to conceive yet. Urofollitropin may also be used to cause the ovary to produce several follicles, which can then be harvested for use in gamete intrafallopian transfer (GIFT) or in vitro fertilization (IVF).

Urofollitropin is to be given only by or under the supervision of your doctor. It is available in the following dosage form:

Parenteral
• Injection (U.S. and Canada)

Urea C 14 is a radiopharmaceutical (ray-dee-oh-far-ma-SOO-ti-kal ) . It is used to diagnose stomach ulcers caused by a certain kind of bacteria known as Helicobacter pylori or H. pylori.

This agent is taken by mouth. If any H. pylori bacteria are present in the stomach, they will cause the urea C 14 to be broken down into radioactive carbon dioxide gas. When you breathe out by the mouth, the amount of radioactive carbon dioxide can be measured to see whether the bacteria are in your stomach.

This agent is a radioactive agent. However, with the small amounts in the capsule that is used for the test, the radiation your body receives is very low and is considered safe.

This agent is to be given only by or under the direct supervision of a doctor with specialized training in nuclear medicine. It is available in the following dosage form:

Oral
• Capsules (U.S.)