CHAPTER 7 ORAL PHARMACOLOGY

Pharmacology is a basic medical science that deals with the study of drugs. Drugs are chemical compounds used in the prevention, diagnosis, and treatment of diseases and other abnormal conditions. This chapter covers some of the drugs used in dentistry.

As a Dental Technician, you will be required to assist in procuring, labeling, and storing drugs. You must also be aware of what drugs the dental officer prescribes and uses during dental procedures. Certain drugs and medicines used in dentistry have side effects on patients, which could turn into a possible medical emergency. Misused or mislabeled drugs can also present a real hazard to your patient's safety. You must have full knowledge of what drugs and medicines are being used in your clinic, hospital, or department. Only authorized personnel should prescribe, dispense, and administer drugs and medications. The Manual of the Medical Department, chapter 21, gives guidance on pharmacy operation and drug control.

DRUG STANDARDS

Many textbooks are available that describe commercially available drugs used in dentistry and medicine. They provide standards for drugs of therapeutic usefulness and pharmaceutical necessity, and also list composition, action and use, administration and dosage, precautions and side effects, dosage forms available, and common (generic) name of the drugs. Your command library is required to have these textbooks available for use.

MEDICATION AND ADMINISTRATION

The quantity of a drug to be prescribed at one time or the total quantity administered and method of administration of drugs are dependent on several factors. This section will cover some of the methods of administering and some of the factors affecting dosage calculations that a dental officer will use.

DOSAGE

The amount of medication to be administrated is referred to as dose. Doses are listed as an average therapeutic dose and are known as "usual adult doses." The following terms are used in connection with doses.

Therapeutic Dose

The therapeutic dose is also referred to as the normal adult dose, the usual dose, or average dose. It is the amount needed to produce the desired therapeutic effect.

Dosage Range

Dosage range is a term that applies to the range between the MINIMUM amount of drug and the MAXIMUM amount of drug required to produce the desired effect. Many drugs, such as antibiotics, require large initial doses that are later tapered to smaller amounts. A TOXIC dose is the amount of drug that will produce symptoms of poisoning; while a MINIMUM LETHAL dose is the least amount of drug that can produce death.

FACTORS AFFECTING DOSAGE

With the administration of medicines used in dentistry, the dental officer must consider many factors with each patient that affects the dose, method of administration, and frequency of the dose. Although a dental officer prescribes or administers the amount to be given, you need to know how and why these quantities are determined. Two primary factors determine or influence the dose: age and weight.

Age

Age is the most common factor that influences the amount of a drug to be given. Infants, children, and elderly patients are more susceptible to drug action and as a general rule, should receive smaller doses than others.

Weight

In the calculation of dosages, weight has a more direct bearing on the dose than any other factor, especially in the calculation of pediatric doses.

METHODS OF ADMINISTRATION

In dentistry, drugs are introduced into the body by different routes, each serving a specific purpose. We will cover parenteral, oral, inhalation, and topical administration of drugs next.

Parenteral

Parenteral medications are those introduced by injection. All drugs used by this route must be pure and sterile. Always check the solution to ensure it has not expired and is clear in color. Several types of parenteral administration can be used in dentistry.

Intravenous\The drug is introduced directly into the vein. Example: Intravenous sedation. Guidance to dental treatment facilities for the administration of outpatient anesthesia services in intravenous (IV) sedation to dental patients can be found in BUMEDINST 6710.67.

Infiltration\This method that is commonly used to anesthetize maxillary teeth. The dental needle and anesthetic are placed into the mucosa along the side of the tooth (facial aspect) and alveolus that is being treated. This technique is possible because the porous composition of alveolus cancellous bone allows the anesthetic to soak through the bone and anesthetizes the apices of the teeth. It is also used in procedures such as biopsy, gingivectomy, frenectomy, and the excision of abnormal tissue.

Block\Because the mandibular bone is very dense, infiltration techniques cannot always be used to achieve adequate anesthesia. A block technique is the most effective means to achieve anesthesia of the mandibular teeth. A dentist will use various types of blocks to anesthetize specific areas. When performing a block technique, the dentist will place the needle and anesthetic into the mucosa and aim them near a specific nerve where the solution is deposited. The area of the nerve is blocked and all surrounding areas the nerve branches off to are also anesthetized. When a mandibular block (inferior alveolar nerve block) is performed, the patient will experience anesthesia on half of the mandible, including the teeth and lower lip.

Periodontal ligament injection\If this procedure is needed, it can be used instead of an infiltration injection. The needle and anesthetic are placed directly into the periodontal ligament along the side of the tooth, where the solution is deposited under pressure. This injection is very painful.

Oral

Oral administration of medications comes in the form of tablets, capsules, liquids, and suspensions. Dental patients may receive medications by this method preoperatively (before) or postoperatively (after) a dental procedure. Another route closely associated with oral administration is SUBLINGUAL. The drug is placed under the tongue and is rapidly absorbed directly into the blood stream. An example is nitroglycerin sublingual tablets.

Inhalation

Inhalation is the introduction of medication through the respiratory system in the form of a gas, vapor, spray, or powder. The three major types are vaporization, nebulization, and gas inhalation. The most common type of gas inhalation used in dentistry is nitrous oxide sedation and will be discussed later in the chapter.

Topical

Topical agents are applied to a particular surface area of the skin being treated. Examples of topical agents are ointments, creams, lotions, shampoos, paste, gels, and liquids. Dental topical agents will be discussed in this chapter under anesthetics.