On a study that suggests that children who attend school near a fast-food restaurant are more likely to be obese than kids whose schools are further from the grease.
How much more likely? Five percent, after other factors (income, education, race) are taken into account. Maybe the researchers have declared five percent to be a statistically significant number, but “statistically significant” and “meaningful to non-statisticians” often do not mean Read more

one of today’s AP stories, should be.
Two insurance giants, America’s Health Insurance Plans and the Blue Cross and Blue Shield Association, have written to senators indicating that they are willing to phase out premiums that vary by prior health history if Congress requires all Americans to purchase coverage.
That is bad, bad news for healthy people like me.
It’s key that the insurance companies are making this offer in exchange for forcing Read more

Development plans for new drugs should include screening for potential drug interactions at an early stage. Structural chemistry and other chemical properties will give a broad idea of how the drug may be absorbed, transported, metabolized and excreted. Mechanistic studies to elucidate the mechanism of action will give indications for possible interactions with other drugs acting at the same site. In vitro and in vivo investigations on hepatic enzyme systems can be carried out to investigate the substrate potential and/or capability for inhibition or induction of liver enzyme systems; this information can then be used to guide investigations of metabolic interactions that may be of eventual clinical significance. The animal toxicokinetics may also provide information about what can be expected in humans. Read more

Most of these drug interactions involve displacement of drug from plasma proteins, thus increasing the free/bound ratio for drug concentration. When the free moieties are those that are pharmacologically active, then unexpectedly exaggerated responses result from standard doses. Most (but not all) such interactions are unwanted. Almost any nonsteroidal anti-inflammatory drug (NSAID) displaces warfarin, thus enhancing its anticoagulant effect and rendering the patient liable to unexpected ecchymosis or more serious hemorrhagic adverse events. Similarly unwanted are the interactions between phenytoin and thyroxine (sedation and thyrotoxicosis), and salicylates with tolbutamide (hypoglycemia). Oral contraceptives compete for albumin-binding sites, and phenytoin doses may need to be adjusted when the former are introduced. A rare example of a beneficial drug interaction at this locus are the use of NSAIDs with some glucocorticoids, where enhanced anti-inflammatory effects of the latter can result, even though a relatively low dose has been administered. Read more

In recent years, the role of over-the-counter (OTC)
medication in the overall health system has
increased dramatically. The increased interest in
and availability of OTC medications is being driven
by several factors: Read more

Whatever the route of administration, a drug must reach its site of action. In order to do this, the drug will have to cross several cell membranes to reach the blood (unless it is injected intravenously).
The three ways by which substances, including drugs, can cross cell membranes are simple diffusion, facilitated diffusion and active transport. Read more

Oral administration
The vast majority of drugs are administered by mouth as pills, capsules, tablets or liquids. Following oral administration, absorption of a drug is from the stomach or intestine directly via the hepatic portal system to the liver before reaching the general circulation. The liver is the main site of drug metabolism and inactivation (see page 20). Many factors affect drug absorption from the gastrointestinal tract, including lipid solubility of the drug; its molecular weight; the pH of the local environment; the surface area of the absorbing membrane; gastric emptying time; the rate of removal from the gastrointestinal tract by the blood and the degree of plasma protein binding of the drug once in the blood stream. Read more

Chapter overview
If a drug is to have a therapeutic effect on the body, it first has to reach its site of action. In order to do this a drug has to be administered in some way. Unless the route of administration is directly into the blood stream, the drug has to be absorbed, usually by diffusion. Once absorbed, distribution of the drug to different parts of the body follows. This necessarily includes passage through the liver. Most drugs are treated as potentially toxic substances and are metabolized by the liver. This detoxifies them and some drugs are almost totally inactivated on first pass through the liver. Eventually a drug will be excreted from the body. This usually occurs via the kidneys, although some drugs can be lost in faeces or exhaled air. This chapter discusses the processes of administration, absorption, distribution, metabolism and excretion of drugs together with factors affecting these processes. Collectively, these processes describe drug disposition, the way in which the body handles drugs. The study of the fate of drugs in the body is known as pharmacokinetics.
Administration of drugs
In order to get to their site of action in the body, drugs have to be administered in some way. There are two major routes of drug administration: enteral and parenteral. Enteral means to do with the gastrointestinal tract and includes oral and rectal administration. The parenteral route includes all other means of drug administration. There are many routes of parenteral administration, some of which are intended for a drug to have a systemic effect and others for a local effect. See Figure 2.1.
(In some definitions, parenteral is synonymous with injection (for example in the Medicines Act), but here the term is used to describe all routes of administration that are not enteral.)

All drugs have at least three names: the chemical name, the generic name and the proprietary name. Chemical names can be complicated and difficult to remember and are not used in this book. A generic name is a drug’s official name and the majority of drugs in this book are referred to by their generic names. The proprietary name is the name given to a drug by the manufacturing company. As the same drug can be manufactured by several different companies, a drug can have multiple proprietary names and this can be confusing. Hence, proprietary names have been avoided in this book except where the proprietary name is in common usage. In the United Kingdom, the generic name is known as the British approved name (BAN ). Read more

Patient compliance is important for successful drug therapy. Compliance in this context is defined as the extent to which the patient follows the clinical prescription. Non-compliance and reasons why patients do not always take drugs as prescribed should be appreciated. Some common reasons for non-compliance are that the patient has doubts about a drug’s effectiveness, they believe they are cured, they misunderstand instructions, dosage regimes are too complicated, or they experience unacceptable side effects. Health care professionals play an important role in improving compliance. This is particularly important if a drug is for serious conditions like epilepsy, glaucoma or hypertension, or is for infection because of the problem of drug resistance. Well-informed patients are more likely to be compliant. Read more