term prescription of Schedule II or III substances, prescribers typi- cally do not increase dosages over a long-term period and may refer patients for psychological treatment when they present with drug-seeking behavior. Signs of withdrawal may include hallucina- tions, tremors and emotional distress. Chronic pain management currently presents a life-threatening epidemic around the world, and notably in the United States. The FDA also regulates the contents of drug labels. A medication label must include contact information for the distributing phar- macy; the dispensing date; a numeric identifier for a given pre- scription; contact information for the patient; medication name; strength; dosage form; quantity; National Drug Code number; manufacturer; refill information; name of prescribing physician; and expiration date (Watkins, 2013, p. 70). A medication contain- er may also contain warning labels regarding the best way to take a medication, as well as recommendations to prevent potentially hazardous scenarios. tions have been upgraded based on visualization of three-dimen- sional receptor shapes. Drug reactions are tied to chemical bonds of graded force values. Drugs that bind by means of weak chemical bonds are more se- lective, while drugs with stronger bonding capabilities are more general. Specific bond types include electrostatic, covalent and hydrophobic. Electrostatic bonds are commonplace linkages between charged ionic molecules and weaker hydrogen bonds or via various short-range attractive electrostatic forces. In con- trast, covalent bonds are typically strong and often irreversible. A common example includes aspirin (acetylsalicylic acid) binding to cyclooxygenase enzymes in platelets, the physiologic effects of which are reversed over a period of several days. Hydrophobic forces drive interactions between highly lipid-soluble drugs and lipid cell membranes. Drug molecular size is variable and quantified by the common measure of molecular weight (MW). General pharmaceutical weight ranges from 100 to 1000 MW. The lower limit of molecular weight is often related to specificity of function. One hundred MW provides a low end to ensure selective binding, thereby prohibit- ing a drug molecule from binding with other receptors. The up- per limit is related to mechanism of transport requirements. Drugs with higher molecular weight generally cannot diffuse across vari- ous biological membranes. Therefore, medications with higher molecular weight must be administered directly into the intended biological compartment (Katzung, 2018, p. 3).
Substance abuse is the harmful or hazardous use of chemical agents, in which the individual adapts poorly under the influence of the substance. Consideration and examination must be in- cluded for patients who present with potential signs of substance abuse, which may mimic signs of a given pathology. Addiction is a compulsive urge to take a drug, while often rejecting all other ac- tivities. The confounding factor is that patients often begin taking an addictive drug for the purpose of managing pain after injury and develop tolerance over a given period of time (Watkins, 2013, p. 58). In addition, a person may experience habituation, which is psychological tolerance of a given drug, which leads to requiring increasing amounts to reach a desired effect. Substance abuse is more detectable in chronic stages, as individuals often adapt and function appropriately early on. Symptoms of substance abuse include excessive weight changes, sweating, tremors and coor- dination impairment; changes in sleeping habits, restlessness, ir- ritability and emotional lability; digression in personal hygiene; and/or lapses in memory (Watkins, 2013, p. 60). Although pain management following acute injury or surgery may require short- Pharmacology: General principles A drug can be generally defined as a substance that facilitates change in biologic function by way of its chemical actions. A drug molecule typically acts as an agonist or antagonist upon an iden- tifiable receptor, or target molecule that serves a governing role in the biologic system. Drugs may be created within the body, or by external means. A drug molecule must have the proper shape, electrical charge, size and atomic composition in order to act to- gether with a given receptor. The shape of a drug molecule is based on the idea of a lock- and-key fit: A given drug molecule shape is complementary to a specific receptor site. In addition, the chemical structure of a drug may change along the course toward a target site. This concept is somewhat fluid due to the chiral nature of biology. Chirality is derived from the Greek word for “hand,” and may be defined as the naturally occurring asymmetric forms of a given chemical compound. Although variable formations of a drug constitute the same chemical, they cannot be superimposed over each other. Thus, a given pharmaceutical may contain some molecules that fit better than others upon a given receptor site. This is a facet of pharmacology that remains under development, as the study of formulating uniform drug molecules to enact a more “pure” link to intended receptor sites is far from the current state of affairs. This concept is known as “rational drug design” (Katzung, 2018, p. 4). Over the past 30 years, continued study and technological advancements have focused on adapting to individual shapes of receptor sites, which has led to progress. Some current medica-
BIOPHARMACEUTICAL ROUTE
inhalation to reach the bronchioles. Those that enter the blood- stream are regulated by autonomic physiologic functions that af- fect blood flow, such as arterial dilation during digestion and arte- rial constriction to redirect blood flow. The most common drug forms include crystals and molecules, which can then be administered in a variety of formats includ- ing tablets, capsules, suppositories, solutions, suspensions oint- ments, creams, gels and aerosols (Amiji, 2014). Depending on the intake method, the drug will be subject to variable forms of physi- ologic metabolism prior to reaching systemic circulation. The proportion of a drug present for systemic circulation is known as bioavailability . Common processes within the body that decrease bioavailability include pre-systemic metabolism, incomplete dis- solution, incomplete absorption through the epithelia, and chemi- cal degradation. Processes by which a drug travels and affects a target can be cal- culated – known as pharmacokinetics – and are categorized into stages. Stages include liberation from dosage form, absorption into the bloodstream, distribution throughout the body, metabo- lism within the body, and excretion out of the body (Amiji, 2014). This series is denoted with the acronym LADME. Liberation entails
Pharmaceuticals employ their effects by interacting with biologi- cal targets found within cells, inside cell membranes, or in vari- ous body fluids outside a cell membrane (Amiji, 2014). Targets are structures and molecules linked to a specific disease and are most often macromolecules such as proteins and/or nucleic ac - ids. Protein targets include enzymes, ion channels, structural pro- teins, membrane transport proteins, hormone receptors, as well as G-protein coupled receptors. By interacting with targets, drugs promote or inhibit biochemical and physiologic processes. Drugs generally target macromolecules localized within body tissues and fluids. Drug administration may be enteral, parenteral and/or percutane- ous. Enteral administration is marked by drug entry via the gas- trointestinal system and includes entry by mouth, rectum or tube application to this region. Parenteral administration bypasses the intestines and includes intravenous, intramuscular, subcutaneous or intradermal injection. Percutaneous administration includes inhalation, sublingual, topical and transdermal (Watkins, 2013, p. 14). While the majority of drugs reach their targets by way of the bloodstream, others do not. Common examples of targets that bypass the bloodstream include the oral dispensation to the intestinal lumen, topical agents applied to the dermis, and oral
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