Tamoxifen is an estrogen blocking agent that has recently been found to reduce the risk of breast cancer in women by as much as 40-50 percent. This remarkable finding may have implications for prostate cancer in men due to the effects of testosterone on the prostrate gland. The exact mechanism of action is unknown, but the drug serves to block estrogen receptors that allow cancer cell formation when bound by estrogen. Side effects include an increase in the incidence of uterine cancer, and tamoxifen has been reported to enhance the formation of cataracts.
Urea is produced in the liver to remove toxic ammonia from the body. Urea travels in the blood to the kidneys where it is excreted via the bladder in the urine.
Polarised light micrograph.
Caffeine is a central nervous system stimulant most commonly found in the coffee we drink every morning. As a drug, caffeine is used to help restore mental alertness and to prevent drowsiness. Like most xanthines that serve as the nucleus for pharmacological agents, caffeine is rapidly absorbed and distributed in all body tissues and fluids including the central nervous system, fetal tissues, and breast milk. Caffeine is cleared from the body through metabolism and excreted in the urine. Symptoms of overdose include insomnia, restlessness, tremor, delirium and tachycardia.
Benzoyl peroxide crystals
Benzoyl peroxide is primarily used in the treatment of acne vulgaris due to the antibacterial activity that these types of peroxides display. The drug is marketed under a variety of trade names in over 200 formulations. In treating patients with acne, the disappearance of acne coincides with the reduction of both the levels of P. acnes bacteria and free fatty acids. Benzoyl peroxide is absorbed in the skin where it is metabolized to benzoic acid and then excreted as benzoate in the urine. Side effects consist mainly of skin irritation including burning, blistering, crusting, itching, severe redness, and skin rash.
Aspirin was originally extracted from willow bark but is actually produced in all plants as a defence mechanism in response to damage or attack. Much higher levels are therefore found in less than perfect fruit and vegetables. Aspirin is used to treat pain, reduce fever, and prevent heart disease and cancer. Some people think it should be reclassified as a vitamin.
Colour-enhanced scanning electron micrograph.