HEALTH AND MEDICAL PRODUCTS:Vitamin E

Vitamin E

In 1922, H. Evans and K. Bishop discovered vitamin E in green leafy vegetables and wheat germ while performing growth experiments with laboratory rats. Vitamin E refers to a mixture of several related fat-soluble compounds known as tocopherols. Vitamin E is a generic descriptor for all tocol [2-methyl-2-(4,8,12-trimethyltridecyl)chroman-6-ol(I, R1 = R2 = R3 = H)] and tocotrienol derivatives exhibiting qualitatively the biologi- cal activity of a.-tocopherol. Chemically related to sex hormones, vitamin E is stored primarily in muscle and adipose (fat) tissue, and to a lesser ex- tent the reproductive organs, within the body. Found largely in plant materials, including wheat germ, vegetable oils, nuts, seeds, whole grains, and dark green leafy vegetables, this vitamin tends to be resistant to heat, light, and acid exposure but is unstable in the presence of oxygen. Other sources of vitamin E include meats, milk, and eggs. The a.-tocopherol [2,5, 7,8-tetramethyl-2-(4',8',12'-trimethyltridecyl)-6-chromanol; C29H50O2] molecule is the most potent of the tocopherols. Vitamin E is absorbed from the intestines and subsequently delivered to the tissues and liver, and it easily accumulates in cellular membranes, fat deposits, and other lipoproteins within the bloodstream. Its major function is to act as an antioxidant in preventing the peroxidation of polyunsaturated membrane fatty acids and cholesterol by scavenging free radicals and molecular oxy- gen. Thus, vitamin E, along with the antioxidant capabilities of vitamin C, assists in preventing oxidative damage to cell membranes and atherosclerosis. Vitamin E also has been used to promote fertility.

HEALTH AND MEDICAL PRODUCTS:Vitamin D.

Vitamin D

While researching a solution to the bone disease called rickets in 1922, E. Mellanby discovered vitamin D. In the United States, the enrichment of milk with this vitamin was, and continues to be, extremely effective against rickets, which is the faulty mineralization of bones and teeth in growing young children, producing soft bones and conditions known as “bowlegs” and “knockknees.” Normally, a vitamin is defined as a substance that is essential for the maintenance of life-sustaining metabolic body processes yet is not synthesized by the body on its own. The single ex- ception to this rule is vitamin D, which can be synthesized in the skin, but only when exposed to direct sunlight (ultraviolet light). Vitamin D refers to a group of chemically distinct steroids that exhibit qualitatively the biological activity of calciol [also called cholecalciferol; vitamin D3; (3�,5Z,7E)-9,10-secocholesta-5,7,10(19)-trien-3-ol; C27H44O]. Stable when exposed to heat, light, acids, alkalis, and oxidation, vitamin D is a fat-soluble compound concentrated in the liver, skin, and kidneys that is essential for calcium and phosphorus metabolism in animals. Vitamin D is therefore important for normal mineralization of bone and cartilage, neuromuscular functioning, tooth formation, and blood clotting. The biologically active form of the hormone is 1a,25-dihydroxycholecalcif- erol, also called calcitriol. Active calcitriol is derived from ergosterol (pro- duced in plants) and from 7-dehydrocholesterol (produced in the skin). After ultraviolet irradiation, ergosterol is converted to ergocalciferol (vitamin D2) in plants, and 7-dehydrocholesterol is converted to cholecalciferol (vitamin D3) in the skin. The same enzymatic pathways in the body then process vitamins D2 and D3 to D2-calcitriol and D3-calcitriol, respectively. Cholecalciferol (or ergocalciferol) is then absorbed from the intestine and transported to the liver for further chemical modification. For example, in the liver, cholecalciferol is hydroxylated to form 25- hydroxy-D3, which is the major blood-circulating form of vitamin D in the body. Subsequent conversion of 25-hydroxy-D3 to calcitriol (its bio- logically active form) occurs in the kidneys and bone tissues. Calcitriol functions in concert with both parathyroid hormone and the hormone calcitonin to regulate blood serum calcium and phosphorus levels. Major dietary sources of vitamin D include fish liver oils, egg yolk, butter, and fortified milk.

HEALTH AND MEDICAL PRODUCTS:Vitamin A.

Vitamin A

In 1913, T. Osborne and L. Mendel, while conducting experiments using rats, discovered that butter contained a growth-promoting, fat- soluble nutrient necessary for development. Soon known as vitamin A, its chemical character was established in 1933, and it was first synthesized in 1947. Vitamin A consists of three biologically active molecules: retinol [3,7-dimethyl-9-(2,6,6-trimethyl-1-cyclohexen-1-yl)-2,4,6,8-non- atetraen-1-ol; C20H30O], retinal (retinaldehyde), and retinoic acid. Each of these compounds is derived from the plant precursor molecule, �-car- otene (a member of a family of molecules known as carotenoids). �-Car- otene, which consists of two molecules of retinal linked at their aldehyde ends, is also referred to as the provitamin form of vitamin A. Ultraviolet light inactivates vitamin A, so it is often destroyed via oxidation upon ex- posure to heat, light, or air. Within the intestine, ingested �-carotene is cleaved via enzymes to initially yield retinal and then subsequently re- duced via enzymes to retinol. Retinol is esterified, delivered to the blood, and then delivered to the liver for storage as a lipid ester. Thus, nearly 90 percent of vitamin A within the body is contained within the liver. Di- etary sources of vitamin A include the provitamin precursor carotene, found in carrots, deep-yellow and deep-green leafy vegetables, and vita- min A, found in fish liver oils, egg yolk, liver, whole milk, butter, and cheese. Vitamin A has three major roles within the body: gene regulation, proper visual functioning, and general body organ health and maintenance. Retinol and retinoic acid are considered hormones of the steroid/ thyroid hormone superfamily of proteins. Within cells, both retinol and retinoic acid bind to specific receptor proteins, and this receptor-vitamin complex then interacts with several genes involved in growth and differentiation to affect their expression. For example, gene expression pat- terns involved with early processes of embryological development, including organogenesis and limb development, are affected by retinoic acid. Vita- min A has a direct role in the process of vision, as the photosensitive compound of most mammalian eyes is a protein called opsin (present in the photoreceptor rod cells within the retina of the eye), which is covalently coupled to an aldehyde form of vitamin A (cis-retinal). Expo- sure of the eye to ultraviolet light results in a series of reactions within the photoreceptor cells that are mediated by photon absorption by cisretinal, which eventually leads to propagation of nerve impulses from the optic nerve of the eye to the brain, where vision is processed. Retinol also functions in the synthesis of certain glycoproteins and polysaccha- rides necessary for mucus production and normal growth regulation within most body organ systems. For example, vitamin A is required to maintain the integrity of the skin and mucus membranes, normal bone and tooth development, and normal reproductive capabilities and additionally acts as an antioxidant to provide anticancer and antiatherosclerosis effects.

HEALTH AND MEDICAL PRODUCTS:VITAMINS.

VITAMINS

Within complex biological organisms, nutrients such as proteins, carbohydrates, and fats serve as building blocks and combine with various other substances to yield energy and maintain cellular functioning. These chemical reactions are catalyzed (accelerated) by individual enzymes, which are located in specific body regions. Vitamins are potent organic (carbon- based) compounds that mainly function as coenzymes (or parts of coenzymes) that individually act in concert with each enzyme to accomplish a specific type of reaction catalysis process. Vitamins are classified as either fat-soluble or water-soluble. Fat-soluble vitamins (e.g., A, D, E, and K) bind to ingested fats and are absorbed into the body along with their digestive products. Except for vitamin K, fat-soluble vitamins are generally stored within the body. Water-soluble vitamins (e.g., B complex and C) are absorbed along with water from the gastrointestinal tract, and unless metabolically used, they are usually excreted in the urine. A noted exception regarding absorption is water-soluble vitamin B12, which must first bind to a chemical called intrinsic factor, which is produced by the stomach, to be absorbed into the body.

These essential organic compounds are biologically required only in small amounts, but deficiency tends to result in a diseased state for the individual. With a few noted exceptions (e.g., vitamins D, K, and B3), most vitamins are not manufactured within the body and thus must be obtained via food sources or direct vitamin supplementation. The value of certain foods in maintaining health was recognized long before the first vitamins were actually isolated and characterized. Nearly 3,500 years ago, for example, Egyptians recognized that night blindness (caused by vitamin A deficiency) could be treated with specific foods. In the eighteenth century, it was demonstrated that the addition of citrus fruits to the diet could prevent the development of scurvy (caused by vitamin C deficiency). In the nineteenth century, it was shown that substituting un- polished for polished rice in a rice-based diet could prevent the development of beriberi (caused by vitamin B1 deficiency). In 1906, British biochemist F. Hopkins demonstrated that foods contained necessary “accessory factors” in addition to proteins, carbohydrates, minerals, and water. The word “vitamin” became a modern vocabulary term as shortened from the original word vitamine, as used by Polish chemist C. Funk in 1912 to describe the “vital amine” (a compound containing a nitro- gen bound to three hydrogen atoms [-NH3] that is vital to our health) antiberiberi accessory growth factor substance then discovered in unpolished rice. The term “vitamin” soon came to be applied to all accessory growth factors in general when many scientists identified, purified, and synthesized the thirteen vitamins and discovered that not all of the factors contained the nitrogen-based chemical amine groups. Vitamins were originally categorized based on their body function and assigned letter names to simplify discussion. As their chemical structures were deter- mined, chemical names were also used.

Human vitamin requirements are generally expressed in terms of the recommended dietary allowance (RDA). These RDA values, as established by the Food and Nutrition Board of the National Academy of Sciences/National Research Council in the United States and by the Food and Agriculture Organization and World Health Organization for different worldwide population groups, represent the amount of essential nutrients that, if acquired daily, are considered sufficient to meet the known nutritional requirements of most healthy individuals within the population. In some cases, the average requirements are not known with precision; RDA values are then based on average dietary intake within a population, plus extra as a margin of safety to account for increased demands (e.g., during illnesses, etc.). While once expressed in terms of international units, the strength of a vitamin or the amount of a vitamin necessary to produce a certain biological effect is currently expressed directly in micrograms or milligrams (metric weights). Many vitamins work together to regulate several body processes, and either an overabundance or insufficient amount of vitamins may potentially disturb the internal balance, or homeostasis, within the body and potentially lead to a disease state or, in some cases, death.

Fat-soluble vitamins, including A, D, E, and K, seem to have highly specialized functions. The intestine absorbs fat-soluble vitamins, and the lymphatic system transports these vitamins to various body regions. Be- cause fat-soluble vitamins easily dissolve in lipids (fats), hydrocarbons, and similar solvents, they normally diffuse through the cell membranes and into other lipids of the body, including adipose (fat) tissue and the lipid inclusions within the liver. Thus, the body usually maintains a significant storage reserve of these vitamins, and normal metabolism may persist for quite a long time (usually several months) after dietary sources of these vitamins have been excluded.

HEALTH AND MEDICAL PRODUCTS:TOPICAL ANTI-INFLAMMA TORY TREATMENTS.

TOPICAL ANTI-INFLAMMA TORY TREATMENTS

Inflammation is generally considered a localized physiological response to injury or pathogen infection of the body tissues. Inflammation is categorized as a type of nonspecific response to tissue injury from physical trauma (e.g., impact, abrasion, distortion), intense heat, or irritating chemicals. The common factor among these triggers of inflammation is a cascade involving cell death, connective tissue fiber damage, and/or gen- eral tissue injury. In addition, tissue injury may allow for the introduc- tion of foreign proteins or pathogens (disease-causing agents) such as viruses, fungi, and bacteria. Overall, the changes within the interstitial biological environment lead to a complex process called the inflamma- tory response. The purpose of this response includes temporary repair of the damaged tissue at the injury site and prevention of additional pathogen entry, prevention (or slowing) of the spread of pathogenic agents to other body areas, disposal of cell debris and pathogens, and mobilization of systemic immune defenses to allow for regeneration and wound healing. Such a process causes an increase in vasodilation (dilation of blood vessels) and interstitial fluid accumulation at the injury site, an alteration in the chemical composition of interstitial tissue fluid, and the release of chemical signals (e.g., prostaglandins and histamine), protein factors (e.g., heparin, kinins, complement, and lymphokines), and potassium ions. For example, histamine (released from cells called mast cells and basophils) promotes the vasodilation of local arterioles, increases the permeability of local capillaries, and promotes exudate formation, whereas prostaglan- dins (fatty acid molecules produced from arachidonic acid and located in all cell membranes) sensitize blood vessels to the effects of other inflammatory mediators, induce pain, and allow for the generation of pain- and inflammation-causing free radicals.

Four key medical signs of acute (short-term) inflammation at an ana- tomical body site are redness and heat (attributable to the increased blood flow and blood volume), swelling, and the sensation of pain (attributable to the increased presence of interstitial fluid exudates and edema-causing adjacent nerve ending stimulation). Many over-the-counter products used as topical anti-inflammatory treatments typically provide temporary relief from minor skin inflammation, itching, and superficial rash caused by medical conditions such as eczema, psoriasis, hives (urticaria), seborrheic dermatitis, and diaper rash and from skin contact with potential allergic reaction-causing environmental factors such as soaps, detergents, poison ivy, poison oak, poison sumac, insect bites, jewelry, and cosmetics. These topical treatments typically contain the compound hydrocortisone (i.e., cortisol; C21H30O5), which is a steroid hormone produced by the cortex of the adrenal (suprarenal) gland that is naturally secreted in a characteristic diurnal rhythm and is manufactured synthetically for medical use. Topical corticosteroids (including hydrocortisone) share potent combined anti-inflammatory, antipruritic (relieving and/or preventing itching), and vasoconstrictive (constriction of blood vessels) actions. Hydrocorti- sone inhibits inflammation and pain by stabilizing lysosomal membranes and preventing vasodilation, potentially acts as an antioxidant to counteract the production of free radicals, relieves the sensation of itching by inhibiting the release of histamine, and diminishes redness and swelling by enhancing the vasoconstrictive effects of the hormone epinephrine. These combined effects cause an overall depression of the local inflam- matory response cascade to provide temporary comfort while also causing a delay in wound healing.

The extent of topical corticosteroid absorption through the skin and the subsequent therapeutic effect is determined by many factors, including the chemical vehicle (i.e., the chemical consistency of the ointment or cream product containing the hydrocortisone), the integrity of the epidermal barrier (i.e., applying the treatment on normal healthy skin versus diseased or inflamed skin), and the use of protective and occlusive barrier dressings on the skin. Once absorbed through the skin, hydrocor- tisone typically binds to plasma proteins within the bloodstream, is me- tabolized primarily by the liver, and is excreted from the body by the kidneys.

Some topical over-the-counter creams and ointments contain combi- nations of corticosteroids and antibiotics (e.g., bacitracin zinc, polymyxin B sulfate, neomycin sulfate) and are used to treat ear, eye, and skin infec- tions caused by the presence of bacteria. In addition, these products may also contain lubricants (e.g., glycerin, white petroleum, beeswax, light min- eral oil), emulsifiers (e.g., glyceryl stearate, PEG-40 stearate, polysorbate 60, ceteareth-20), emollients (e.g., isostearyl neopentanoate, cetyl pal- mitate), humectants (e.g., stearyl alcohol, purified water), pH-regulating agents (e.g., calcium acetate, sodium citrate), preservatives (e.g., citric acid, sorbic acid, methylparaben, propylparaben), surfactants (e.g., stearyl alcohol, sodium lauryl sulfate), vitamins (e.g., tocopheryl acetate [vita- min E], vitamin A palmitate, vitamin D), solution binders (e.g., malto- dextrin), skin-soothing natural anti-itch products (e.g., Aloe barbadensis leaf juice or gel, Avena sativa [oat] kernel flour), and agents that en- hance hydrocortisone drug permeation through the skin (e.g., isopropyl myristate).

HEALTH AND MEDICAL PRODUCTS:TOPICALANTIBIOTICTR EATMENTS.

TOPICALANTIBIOTICTR EATMENTS

Antibiotics are typically described as antimicrobial agents of natural origin that are produced by microorganisms, which elicit a lethal or growth-inhibitory effect on a range of other types of microorganisms. These agents are molecules produced as secondary metabolites mainly by microorganisms inhabiting the soil, including molds and bacteria. In most cases, antibiotic production seems to be related to the sporulation process of the organismal life cycle. While many hundreds of different compounds possessing antibiotic activity have been identified from microorganisms since the early twentieth century, only a few compounds isolated have been shown to be both clinically therapeutic in the treatment of infectious disease and minimally toxic after administration. The modern under- standing of antibiotics as chemically therapeutic agents started with A. Fleming’s credited 1929 discovery of a fungal (common bread mold) metabolite from Penicilliumnotatum that demonstrated potent bactericidal effects. Termed penicillin, this antibiotic was not isolated and purified until the period of World War II (1939–1945), when two scientists,H. Florey and E. Chain, managed to produce penicillin on an industrial scale for widespread use. In addition, by the 1950s, several other antibiotics were in clinical use as the result of G. Domagk’s 1935 discovery of synthetic chemicals (sulfonamides) with broad antimicrobial activity, along with intensive research concerning other antimicrobial agents of natural origin. Three different antibiotics used in varying concentrations in present- day over-the-counter antibiotic treatments are neomycin, bacitracin, and polymyxin B. These antibiotics are usually formulated within chemically inactive creams or petrolatum-based ointments for topical application.

The range of bacteria or other microorganisms that are affected by a particular antibiotic is termed its spectrum of action. Broad-spectrum antibiotics are those that kill or inhibit a wide range of Gram-positive and Gram-negative bacteria, whereas narrow-spectrum antibiotics are mainly effective against either Gram-negative or Gram-positive bacteria. The Gram stain, named after its developer, C. Gram, is a laboratory staining technique that distinguishes between two groups of bacteria by the identification of differences in the structure of their cell walls. While the cell membrane is the critical barrier of the bacterial cell, separating the inside ribosome and nucleic acid components from the outside of the cell, the cell wall is a rigid structure outside the cell membrane that provides sup- port and protection. Although the cell walls of these bacteria are similar in chemical composition, Gram-positive bacteria remain colored after the staining procedure, whereas Gram-negative bacteria do not retain dye. The cell wall of Gram-negative bacteria consists of a thin layer positioned between an outer lipid-containing cell envelope and an inner cell membrane, whereas the Gram-positive cell wall is much thicker, lacks the cell envelope, and contains additional substances such as teichoic acid (poly- mers composed of glycerol or ribitol).

Many antibacterial agents produce a clinically beneficial effect by interfering with bacterial cell wall synthesis, cell membrane physiology, or protein synthesis. Peptidoglycan (and its synthesis pathway) is a major component of bacterial cell walls and thus one of the major targets of antibiotics in both Gram-negative and Gram-positive bacteria. Eukaryotic cells (cells that contain a true nucleus) within organisms such as humans lack cell walls and peptidoglycan. Other antibiotic compounds may target bacterial protein synthesis because bacterial ribosomes (termed 70S ribosomes) are different from the ribosomes (80S) of humans and other eukaryotic organisms. Thus, antibiotics may exert selective toxicity against bacterial pathogens without deleteriously affecting the consumer taking the antibiotic drug.

The actinomycetes are a large group of soil-inhabiting filamentous bacteria that produce many different chemical classes of antibiotics, including chemicals known as aminoglycosides. These compounds are water- soluble weak bases that are characterized by the presence of an aminocyclitol ring linked by glycosidic bonds to amino sugars in their structure. Within the actinomycetes, the species Streptomyces fradiae produces the broad-spectrum antibiotic neomycin, which causes the premature termination of protein synthesis (translation) in bacteria. Specifically, the ami- noglycosides irreversibly bind to the 30S subunit of the bacterial ribosome and interfere with the formation of the initiation complex to cause misreading of the mitochondrial RNA. First isolated by S. Waksman from a strain of S. fradiae in 1949, neomycin is mainly used topically in the treatment of skin and mucus membrane infections, wounds, and burns. Although used systemically in some cases, it is highly toxic. Neomycin sulfate, often used in topical antibiotic treatments in lieu of neomycin, is the sulfate salt of neomycin B and C, which are also produced by the growth of S. fradiae.

Endospore-forming Bacillus bacterial species produce a chemical class of antibiotics known as polypeptides, including bacitracin and polymyxin B. Polypeptide antibiotics consist of an amino acid chain. Bacitracin (C66H103N17O16S), a metal-dependent polypeptide complex of closely related analogues produced by common soil and water bacteria, including Bacillus subtilis and Bacillus licheniformis, is a narrow-spectrum antibiotic effective against Gram-positive bacteria. It prevents cell wall growth by inhibiting the release of the muropeptide monomer subunits of peptidoglycan from the undecaprenyl pyrophosphate lipid carrier mol- ecule that carries the subunit to the outside of the bacterial cell mem- brane. Binding to the undecaprenyl pyrophosphate lipid carrier impedes the dephosphorylation of the lipid carrier, which then obstructs the re- generation of undecaprenyl phosphate, thus preventing recycling of the bacterial transport system and the cell wall synthesis mechanism. Synthesis of teichoic acid, a key cell wall component in Gram-positive bacteria, which requires the same carrier molecule, is also inhibited. Bacitracin is limited to topical applications because it also interferes with sterol synthesis in mammalian cells by binding to pyrophosphate intermediates, thereby eliciting a toxic response when used systemically in humans.

Polymyxin B, a naturally occurring cyclic decapeptide produced by Bacillus polymyxa, is a narrow-spectrum antibiotic effective against Gram- negative bacteria and is usually limited to topical applications. It consists of a seven-member ring containing four diaminobutyric acid (Dab) resi- dues, one threonine residue, and a hydrophobic segment (i.e., dPhe-Leu and a linear amino-terminal region composed of three amino acids, Dab- Thr-Dab, together with an eight- or nine-carbon fatty acid [6-methyl heptanoic acid and octanoic acid, respectively] forming a long hydro- phobic tail). Considered one of the most efficient cell-permeabilizing compounds, it binds to membrane phospholipids within the cell membrane of the bacterium and thereby interferes with membrane physiological function. Polymyxin B acts a detergent, increasing the permeability of the membrane to cause the contents of the bacterial cell to leak out. Because of similarities in the phospholipid chemical composition of bac- terial and eukaryotic cell membranes, polymyxin B is rarely used as a systemic antibiotic treatment in humans, as it does not specifically target and destroy only bacterial cell membranes. Polymyxin B sulfate, frequently used in topical antibiotic treatments in lieu of polymyxin B, is the sulfate salt of polymyxin B1 and B2, which are also produced by the growth of B. polymyxa.

Topical antibiotic treatments typically also include a local anesthetic (numbing agent), such as pramoxine hydrochloride, that interferes with the function of nerves that sense pain.

HEALTH AND MEDICAL PRODUCTS:SPERMICIDE (BIRTH CONTROL PRODUCT).

SPERMICIDE (BIRTH CONTROL PRODUCT)

The human reproductive system is the only organ system in both males and females that is not essential to the life of the individual. Although the reproductive systems of the human male and female possess many differences, their common purpose is to produce offspring and thus perpetuate the species. In general, the role of the human reproductive system is to synthesize, maintain, nourish, and transport functional male and female reproductive cells called gametes. The reproductive system includes gonads, or reproductive organs that produce the gametes and secrete steroid-based sex hormones; ducts that receive and transport the gametes; accessory glands and organs that secrete fluids into the ducts or other accessory structures to allow for adequate lubrication and gamete functioning; and perineal structures collectively called external genitalia that enhance the human sexual response and allow for efficient reproductive functioning during a copulation event between males and females. Male gametes, called sperm, are produced in gonads called the testes, and female gametes, called ova (eggs), are produced in gonads called the ovaries. When a male and a female gamete unite, fertilization, also known as con- ception, occurs. In sexual reproduction, fertilization results in the formation of a completely new and genetically unique organism. Specifically, the single cell resulting from the union and fusion of the male and female gametes, called a zygote, contains a mixture of chromosomes (DNA) from the two parents. Through a development process of repeated mitotic cell divisions and differentiation (specialization), the zygote undergoes grad- ual transformation and maturation within the female uterus into a complex multicellular new human being.

Sperm are specialized cells produced in the male testes, which are paired oval glands measuring approximately five centimeters (two inches) in length and two and a half centimeters (one inch) in diameter that are supported externally by a cutaneous outpouching of the male abdomen consisting of loose skin and connective tissue called the scrotum. Within the testes, septal tissue extensions divide the testes internally into 200 to 300 wedge- shaped compartments called lobules. Each lobule contains one to four tightly coiled tubules called seminiferous tubules. Within the seminiferous tubules, sperm are produced by a unique cellular division process called spermatogenesis. Controlled by hormones including testosterone, the process of spermatogenesis begins during puberty within males and normally continues throughout life. A healthy adult human male produces approximately 400 million sperm daily.

A sperm is a highly adapted and mobile cell capable of reaching and penetrating a female ovum (egg). Each sperm has three distinct regions: the head (genetic region), the midpiece (metabolic region), and the tail (locomotor region). The head is a flattened ellipse containing a nucleus with densely packed chromosomes (DNA) and a dense membranous granule (actually a specialized lysosome organelle) at the tip called the acrosomal cap that contains enzymes, including proteinases and hyaluronidase, which aid in the penetration of the sperm cell into the ovum. A short neck attaches the head to the midpiece, a region containing organelles called mitochondria that absorb nutrients from the surrounding fluid (called semen) and produce energy (in the form of adenosine tri- phosphate) for sperm locomotion. The tail consists of an organelle called a flagellum, which allows the sperm to propel through the female repro- ductive tract in a unique whiplike corkscrew motion.

Contraception (contra = against, cept = taking) and birth control are synonymous terms. While many individuals use various birth control strategies during their reproductive years, readily available OTC chemical methods of contraception containing spermicide chemicals are frequently chosen. Various foams, creams, jellies, vaginal suppositories, sponges, and douches that contain spermicidal agents make the female vagina and cervix unfavorable for sperm survival and thus decrease the likelihood of a successful fertilization event during intercourse. Once the sperm-killing chemicals are inserted into the female vagina to coat the vaginal surfaces and cervical opening into the uterus, relative contraception protection is provided for approximately one hour. Spermicides can be effective when used alone but are significantly more effective when used with physical barrier devices, including condoms, vaginal pouches, diaphragms, cervical caps, or sponges.

For approximately thirty years, one of the most widely used Food and Drug Administration-approved active ingredient spermicides in various OTC contraceptive products has been nonoxynol-9 (N-9). N-9 is an al- most colorless liquid nonionic detergent (surfactant, a surface-active agent) that inactivates sperm via disruption and disaggregation of the outer protective plasma membrane. Thus, the number of active and viable sperm decreases significantly. This activity stems from the ability of nonionic surfactants, which lack a specific charge and possess a hydrophilic head region and a hydrophobic tail region, to dissolve lipid-containing membranes. A nonoxynol [a-(4-nonylphenyl)-w-hydroxypoly(oxy-1,2-ethanediyl) or poly- ethyleneglycol mono(nonylphenyl) ether] is a nonionic surfactant mixture prepared by reacting nonylphenol with ethylene oxide. The hydrophilic (or water-soluble) portion of the molecule contains the polyethylene ox- ide group. The average number of ethylene oxide units (n) per molecule is indicated by the number after nonoxynol (e.g., nonoxynol-9 for n = 9). A multicomponent mixture of oligomers (at least seventeen are known as characterized by high-performance liquid chromatography) in the com- mercially available form, N-9 is used as a spermicidal ingredient in sper- micidal lubricants, both preapplied to spermicidal condoms and packaged separately.