Treatment.

Immune therapy.

Immunotherapy is also sometimes called biologic therapy or biotherapy. It is treatment that uses certain parts of the immune system to fight diseases such as cancer. This can be done in a couple of ways:

• Stimulating your own immune system to work harder or smarter to attack cancer cells
• Giving you immune system components, such as man-made immune system proteins

For a long time doctors suspected that the immune system had an effect on certain cancers. Even before the immune system was well understood, William Coley, MD, a New York surgeon, first noted that getting an infection after surgery seemed to help some cancer patients. In the late 1800s, he began treating cancer patients by infecting them with certain kinds of bacteria, which came to be known as Coley toxins. Although he had some success, his technique was overshadowed when other forms of cancer treatment, such as radiation therapy, came into use.

Since then, doctors have learned a great deal about the immune system. This has led to research into how it can be used to treat cancer, using many different approaches. In the last few decades immunotherapy has become an important part of treating several types of cancer.

Immunotherapy includes a wide variety of treatments that work in different ways. Some seem to work by boosting the body’s immune system in a very general way. Others help train the immune system to attack cancer cells specifically.

Immunotherapy seems to work better for some types of cancer than for others. It is used by itself to treat some cancers, but for many cancers it seems to work best when used along with other types of treatment.

As researchers have learned more about the body’s immune system in recent years, they have begun to figure out how it might be used to treat cancer more effectively. Newer treatments now being tested seem to work better and will have a greater impact on the outlook for people with cancer in the future.

The main types of immunotherapy now being used to treat cancer are discussed in the following sections. They include:

• Monoclonal antibodies: These are man-made versions of immune system proteins. Antibodies can be very useful in treating cancer because they can be designed to attack a very specific part of a cancer cell.
• Cancer vaccines: Vaccines are substances put into the body to start an immune response against certain diseases. We usually think of them as being given to healthy people to help prevent infections. But some vaccines may help prevent or treat cancer.
• Non-specific immunotherapies: These treatments boost the immune system in a very general way, but this may still result in more activity against cancer cells.

Routes of drug administration

The administration of a medicine is a common but important clinical procedure. It is the manner in which a medicine is administered that will determine to some extent whether or not the patient gains any clinical benefit, and whether they suffer any adverse effect from their medicines.

For example, intravenous (IV) furosemide administered too quickly can cause deafness; oral penicillin V given with food will not be well absorbed; over-application of topical steroids will cause thinning of the skin and may lead to systemic side-effects.

Two main factors determine whether or not a drug will reach its intended site of action in the body:

• The bioavailability of the drug;
• How the drug is given (route of administration). 

Bioavailability

Bioavailability is the proportion of an administered drug that reaches the systemic circulation and is therefore available for distribution to the intended site of action.

Drugs that are given by direct IV injection are said to have 100% bioavailability. Some drugs that are particularly well absorbed by the gastrointestinal mucosa may have bioavailability comparable to that of an IV dose – for example the antibiotic ciprofloxacin. Most drugs do not have this availability by the oral route so the dose given orally is usually higher than that given parenterally. For example, the beta-blocker propranolol when given orally is administered in doses of 40mg and above. The equivalent IV dose is 1mg.The route of administration and its formulation (tablet, capsule, liquid) can clearly influence the bioavailability of a drug.

Routes of administration

There are various routes of administration available, each of which has associated advantages and disadvantages. All the routes of drug administration need to be understood in terms of their implications for the effectiveness of the drug therapy and the patient’s experience of drug treatment.

Routes of administration

• Oral
• Sublingual
• Rectal
• Topical
• Parenteral – Intravenous, intramuscular, subcutaneous 

Oral administration

This is the most frequently used route of drug administration and is the most convenient and economic. Solid dose forms such as tablets and capsules have a high degree of drug stability and provide accurate dosage. The oral route is nevertheless problematic because of the unpredictable nature of gastro-intestinal drug absorption. For example the presence of food in the gastrointestinal tract may alter the gut pH, gastric motility and emptying time, as well as the rate and extent of drug absorption.

The extent to which patients can tolerate solid dose forms also varies, particularly in very young and older patients. In such cases the use of liquids or soluble formulations may be helpful. Many drugs, however, are not stable in solution for liquid formulation and in such cases careful consideration should be given to the option of switching to alternative drug treatment.

Difficulties frequently arise with patients who are prescribed modified-release preparations as these must not be crushed or broken at the point of administration. Modified-release formulations can delay, prolong or target drug delivery. The aim is to maintain plasma drug concentrations for extended periods above the minimum effective concentration.

For patients, their main advantage is that doses usually only need to be taken once or twice daily. Damage to the release controlling mechanism, for example by chewing or crushing, can result in the full dose of drug being released at once rather than over a number of hours. This may then be absorbed leading to toxicity or may not be absorbed at all leading to sub optimal treatment.

Nurses should seek advice from a pharmacist or the prescribing doctor if they are uncertain about a formulation of solid dose forms and whether or not they are suitable for crushing.

Sublingual

The sublingual mucosa offers a rich supply of blood vessels through which drugs can be absorbed. This is not a common route of administration but it offers rapid absorption into the systemic circulation. The most common example of sublingual administration is glyceryl trinitrate in the treatment of acute angina.

The pharmaceutical industry has formulated and marketed ‘wafer’-based versions of tablets that dissolve rapidly under the tongue. These are aimed at particular markets where taking tablets may be problematic, such as the treatment of migraine (rizatriptan) where symptoms of nausea may deter patients from taking oral treatments. The formulation is also used to treat conditions where compliance with prescribed drug regimens may be problematic, for example, olanzapine used to treat schizophrenia can be administered by the sublingual route.

Rectal administration

The rectal route has considerable disadvantages in terms of patient acceptability (in the UK at least) and unpredictable drug absorption but it does offer a number of benefits. It offers a valuable means of localised drug delivery into the large bowel, for example the use of rectal steroids in the form of enemas or suppositories in the treatment of inflammatory bowel disease. Antiemetics can be administered rectally for nausea and vomiting and paracetamol can be give to treat patients with a pyrexia who are unable to swallow.

Topical administration

The topical application of medicines has obvious advantages in the management of localised disease. The drug can be made available almost directly at the intended site of action, and because the systemic circulation is not reached in great concentration, the risk of systemic side-effects is reduced. For example:

• The use of eye drops containing beta blockers in the treatment of glaucoma;
• The application of topical steroids in the management of dermatitis;
• The use of inhaled bronchodilators in the treatment of asthma;
• The insertion of pessaries containing clotrimazole in the treatment of vaginal candidiasis.

Topical administration has also become a popular way of introducing drugs into the systemic circulation through the skin. The development of transdermal patches that contain drugs began with the introduction of a hyoscine-based product for the treatment of nausea in the early 1980s.

The market for such products has since grown to include a wide range of disease management areas including the prophylaxis of angina (glyceryl trinitrate), the treatment of chronic pain (fentanyl) and hormone replacement (oestrogens). While the use of transdermal drug administration is not without its problems - for example, some preparations can cause local skin reactions - many patients find it a welcome alternative to taking tablets.

Parenteral administration

Parenteral drug administration can be taken literally to mean any non-oral means of drug administration, but it is generally interpreted as relating to injection directly into the body, by-passing the skin and mucous membranes. The common routes of parenteral administration are intramuscular (IM), subcutaneous and IV.

Advantages of parenteral administration:

• Drugs that are poorly absorbed, inactive or ineffective if given orally can be given by this route
• The intravenous route provides immediate onset of action
• The intramuscular and subcutaneous routes can be used to achieve slow or delayed onset of action
• Patient compliance problems are largely avoided .

Disadvantages of parenteral administration:

• Requires trained staff to administer
• Can be costly
• Can be painful
• Aseptic technique is required
• May require supporting equipment for example, programmable infusion devices

NB: The correct administration of parenteral doses requires the use of appropriate injection technique. If performed incorrectly, for example using the wrong sized needle it can cause damage to nerves, muscle and vasculature and may adversely affect drug absorption.

Intramuscular and subcutaneous injection:

In general the injection of drugs into the muscle or the adipose tissue beneath the skin allows a deposit or ‘depot’ of drug to become established that will be released gradually into the systemic circulation over a period of time. By altering the formulation of the drug, the period over which it is released can be influenced. For example, the formulation of antipsychotic agents such as flupentixol in oil allows them to be administered once a month or every three months.

Intravenous injection

In many respects the administration of medicines via the IV route is an admission that the use of other routes will not allow for an intended therapeutic outcome or goal of the treatment to be met. Not only is the IV route inconvenient for the patient and practitioner, but it carries the greatest risk of any route of drug administration. By administering directly into the systemic circulation either by direct injection or infusion, the drug is instantaneously distributed to its sites of action.

Such administration is frequently complex and confusing. It may require dose calculations, dilutions, information to be gathered on administration rates and compatibilities with other IV solutions, and the use of programmable infusion devices.

Moreover the preparation of IV medicines requires the use of an aseptic technique, often in a ward environment that is unsuited for such work. It is imperative that to minimise the risk of errors occurring in the administration of IV medicines that practitioners can demonstrate their competence to practice safely in this area, and have access to appropriate sources of expert information and advice.

Administration of drugs via enteral feeding tubes

Drugs should only be administered via fine-bore enteral feeding tubes as a last resort and other routes of administration should be considered first. Most drugs are not licensed for administration via enteral feeding tubes.

Interaction can occur between drugs and the enteral feed. Clinically significant interactions include, phenytoin, digoxin, ciprofloxacin and rifampicin. A pharmacist should therefore be involved in any decision to administer drugs via this route.

Drugs

A drug, broadly speaking, is any substance that, when absorbed into the body of a living organism, alters normal bodily function. There is no single, precise definition, as there are different meanings in drug control law, government regulations, medicine, and colloquial usage.

In pharmacology, a drug is "a chemical substance used in the treatment, cure, prevention, or diagnosis of disease or used to otherwise enhance physical or mental well-being." Drugs may be prescribed for a limited duration, or on a regular basis for chronic disorders.

The molecules of drugs are complex, and most of them consist of many hydrogen and carbon atoms, a few oxygen atoms, and one or a few nitrogen atoms. Drugs may also have no nitrogen atoms in it and many may have chlorine atoms in it, such as chloral hydrate.

Recreational drugs are chemical substances that affect the central nervous system, such as opioids or hallucinogens. They may be used for perceived beneficial effects on perception, consciousness, personality, and behavior. Some drugs can cause addiction and/or habituation