Noncompetitive Inhibition occurs when the inhibitory chemical, which does not have to resemble the substrate, binds to the enzyme other than at the active site. Lead binds to SH groups in this fashion. Irreversible Inhibition occurs when the chemical either permanently binds to or massively denatures the enzyme so that the tertiary structure cannot be restored. Nerve gas permanently blocks pathways involved in nerve message transmission, resulting in death. Penicillin, the first of the "wonder drug" antibiotics, permanently blocks the pathways certain bacteria use to assemble their cell wall components.
Transdermal patches (adhesive patches placed on the skin) may also be used to deliver a steady dose through the skin and into the bloodstream. Testosterone-containing creams and gels that are applied daily to the skin are also available, but absorption is inefficient (roughly 10%, varying between individuals) and these treatments tend to be more expensive. Individuals who are especially physically active and/or bathe often may not be good candidates, since the medication can be washed off and may take up to six hours to be fully absorbed. There is also the risk that an intimate partner or child may come in contact with the application site and inadvertently dose himself or herself; children and women are highly sensitive to testosterone and can suffer unintended masculinization and health effects, even from small doses. Injection is the most common method used by individuals administering AAS for non-medical purposes. 
As we age, the balance slowly shifts towards a more catabolic dominant metabolism, initiating the many physical and energetic changes we associate with later stages of life. The body becomes less efficient, losing the ability to keep pace with the rate of break down that is occurring. This shift results in decreased energy levels, physical deterioration, increased susceptibility to illness and injury, and longer recovery times. While this is a natural process that everyone experiences, the choices we make over the course of our lives can greatly improve our body’s ability to age gracefully. A healthy lifestyle that includes proper diet, regular exercise, and good rest is essential.