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Pharmacology and pain control

Margaret Kellett

Introduction

In the practice of clinical dentistry, it is essential for all of the dental team to understand the role of patient medication and how existing medication may complicate delivery of dental care, may predispose the patient to oral diseases and how drugs may be applied in dental care to both control infection and manage pain.

Every patient’s medical history must be checked on every occasion they attend the dental surgery.

Where there is any doubt about the risks associated with medical status or pharmacotherapy interactions do seek guidance from a supervising dentist or the patient’s medical practitioner.

The dental team have a duty to support patients in preventing oral disease through active involvement in smoking cessation activity.

As clinical guidance changes it is important to constantly update our knowledge. The National Institute for Clinical Health and Excellence has made significant change to guidance on risk of infective endocarditis.

Prescribing regulations and the use of the BNF

The British National Formulary (BNF) details all medicines that are prescribed in the UK, with special reference to their indications, cautions, contraindications, side effects, dosage and relative cost. Compiled with the advice of clinical experts, the BNF provides authoritative and practical information on the selection and clinical use of medicines for use in the NHS. Updated every 6 months, published in both paper-based and web versions (http://www.bnf.org/bnf/), it reflects current best practice, in addition to legal and professional guidelines in relation to the use of medicines.

Regulation of prescribing

The Medicines Act 1968 was introduced by the Department of Health and Social Security after a review of legislation prompted by the incidence of severe birth defects that were caused by the drug thalidomide. The Act consolidated previous legislation regarding medicines and introduced a number of new provisions for the control of prescribing of medicines. The legislation established three categories of drugs depending upon the danger which they posed and the associated risk of drug abuse. The categories are:

• Prescription only medicines, which may be sold or supplied to the public only through the provision of a prescription signed by an approved practitioner. Approved practitioners include doctors and dentists. With the exception of controlled drug preparations below certain strength (defined in schedule 5 of the Misuse of Drugs Regulations 2001); all controlled drugs are prescription only medicines.
• Pharmacy medicines are those which, subject to certain exceptions, may be sold or supplied only from registered premises by, or under the supervision of, a pharmacist.
• General sales list medicines may be sold or supplied direct to the public in an unopened manufacturer’s pack from a lockable premises. No controlled drugs are on general sales list.

Current regulation limits the prescribing of medication to doctors, dentists, pharmacists and some nurses. Dental hygienists and dental therapists may, if appropriately trained, dispense medication (most frequently local anaesthetic agents) to patients under the direction of prescribing dental practitioners. The requirement for an individual written prescription for administration of local anesthesia has been simplified by legislation (Statutory Instrument 2000a, www.hmso.gov.uk/acts.htm) permitting Patient Group Directives. In effect this allows specific drugs to be delivered by a defined group of healthcare professionals with the approval of a registered prescriber.

Many patients attending for dental care are taking prescription medication, and the dental hygienist and dental therapist therefore require a knowledge and understanding of such medication and the potential complications which this may cause, either as part of the delivery of dental care or in relation to the patient’s susceptibility to oral disease.

Accessing and using the British National Formulary

The BNF is jointly published by the British Medical Association and the Royal Pharmaceutical Society. The Dental Advisory Group produces advice on drugs in relation to oral and dental conditions. In addition to twice yearly updated printed versions the BNF can be accessed on line at www.BNF.org. The main text contains classified notes on clinical conditions, drugs and preparations. These are divided into 15 chapters, each of which is related to a particular system of the body or aspect of medical care. Each chapter is then divided into sections which begin with appropriate notes for prescribers. These notes are intended to provide healthcare professionals with information to permit selection of suitable treatment. Further information on drug therapy relating to dental treatment can be obtained in the UK by contacting UK Medicines Information (telephone numbers can be found on the UKMi website http://www.ukmi.nhs.uk/).

Guidance on dental and oral conditions is identified by means of a relevant heading (e.g. Dental and Orofacial Pain) in the appropriate sections of the BNF. The notes are followed by details of relevant drugs and preparation. Preparations which can be prescribed by dental surgeons using NHS form FP10D (GP14 in Scotland, WP10D in Wales) are identified within the BNF by means of a note headed Dental Prescribing on the NHS.

The section Guidance on Prescribing includes information on prescription writing, controlled drugs and dependence, prescribing for children and the elderly. Advice is given on the reporting of adverse reactions. The BNF also includes advice on medical emergencies and other medical problems in dental practice, together with a review of the oral side effects of drugs.

Medicines should be prescribed only when clinically necessary and, in all cases, the benefit of administering medication should be considered in relation to the risk involved. In particular, patients should be advised of the potential side effects and complications of prescribed medication. Difficulties in compliance with drug treatment occur regardless of age. Factors contributing to poor compliance with prescribed medicines include:

• Prescriptions not collected or dispensed.
• Purpose of medication not clearly explained.
• Perceived lack of efficacy by the patient.
• Real or perceived side effects.
• Instructions for administration not clear.
• Complicated regimen.
• Unattractive formulation, e.g. unpleasant taste.

Emergency Treatment of Poisoning provides information on the management of acute poisoning when first seen in the home.

Appendices and Indexes include information on interactions, liver disease, renal impairment, pregnancy and breast feeding, and cautionary and advisory labels for dispensing medicines. The Dental Practitioners’ List and the Nurse Prescribers’ List are to be found in this section. The indices contain the manufacturers and the main index.

Prescribing by dental surgeons

Until new prescribing arrangements are introduced for NHS prescriptions, dental surgeons should use form FP10D to prescribe only those items listed in the Dental Practitioners’ Formulary. The Act and Regulations do not set any limitations upon the number and variety of substances which the dental surgeon may administer within the dental surgery or may order by private prescription. Provided the relevant legal requirements are observed, the dental surgeon may use or order whatever is required to manage the clinical situation. Dentists are not required to communicate with the patient’s doctor when prescribing for dental care; however, in any situation where a complex medical condition or therapy may lead to patient risk, then it is essential to do so.

When prescribing the following principles should be applied:

• Never prescribe a drug unless there is good clinical indication.
• Make prescriptions clear.
• Use approved drug names not brand names.
• Always make the source of the prescription clear.
• Always record the prescription details in the clinical notes.
• Avoid prescribing during pregnancy whenever possible.
• Avoid abbreviations; give the name of the drug in full.

The use of antibiotics and antimicrobials in dentistry

Microbial resistance to antimicrobial drugs is increasing and constitutes a major health problem contributing to deaths from hospital-acquired septicaemia. The indiscriminate prescribing of antimicrobials is considered to be a significant contributory factor in drug resistance. Antimicrobial drugs selectively kill sensitive microorganisms, resulting in the emergence of larger numbers of resistant microorganisms. These drug-resistant forms of bacteria can pass on genetic information, thus conferring acquired drug resistance to other commensal organisms and, in addition, to pathogenic species. The three main mechanisms of antibiotic resistance are reduced bacterial permeability, enzymatic alteration of antibiotics and altered target site.

Antibiotics are an important group of drugs in dental therapy. The decision to prescribe an antibiotic should be based upon a thorough history, physical examination, laboratory data and a diagnosis. It is important to record all information, including prescribed drugs, in the patient’s clinical notes.

There are three main indications for the use of antimicrobial drugs in dental treatment:

• If there is a severe or potentially life-threatening infection which will not resolve without the use of antibiotics.
• If an antimicrobial can act as an adjunct to other mechanical therapy in controlling acute or chronic infection.
• When a patient is immunocompromised or is at risk because of a systemic condition, e.g. poorly controlled diabetes or previous use of bisphosphonates.

Potential problems arising from antibiotic use

In addition to the risk of resistant bacteria forms developing, the overgrowth of other organisms (e.g. oral Candida albicans), may be problematic.

Allergic drug reactions are common and range from simple itching and rashes to severe life-threatening conditions, such as anaphylaxis.

Drug interactions with serious consequences can occur with the use of antimicrobial drugs. It is important to check the BNF before prescribing antimicrobials if the patient is taking other medication (e.g. antimicrobials and oral contraceptives).

Antimicrobial drugs may fail to control infection if:

• The incorrect drug is selected (e.g. microorganisms are not susceptible to the chosen drug).
• An incorrect dose and/or duration of drug is prescribed.
• The patient does not comply with the prescription.
• The antibiotic is taken simultaneously with an interfering drug, e.g. an antacid with tetracycline.
• Drainage is inadequate or necrotic tissue has not been removed.
• Infection is with resistant species of bacteria, or there is emergence of resistant species of bacteria.
• The antibiotic fails to reach the infected site.
• There is a poor host response, such as malabsorption, as a result of systemic disease.
• A foreign body, e.g. an implant, is the focus of infection.

Dental use of antimicrobial drugs

Minor surgical care

Antimicrobials are sometimes prescribed for healthy patients when they are scheduled for minor oral or periodontal surgery. There is no evidence to support the routine use of antimicrobials in this way. Postoperative complications following minor oral and periodontal surgery are rarely serious and are readily managed should they arise. There is no evidence to suggest that antimicrobials can improve the outcome of regenerative periodontal surgery.

Although some authors do advocate routine antimicrobial therapy following removal of third molar teeth (to reduce the risk of dry socket, localised infective osteitis), such prescribing practice confers no advantage and current guidelines suggest prophylactic antimicrobials are not usually required. Following simple extraction in the permanent dentition, dry socket (alveolitis) occurs in only 3–4% of cases. Given the low risk:benefit ratio for use of antibiotic prophylaxis, current guidelines do not support the use of antimicrobial prophylaxis to avoid dry socket except in the case of a clear history of previous repeated dry socket following tooth extraction.

Management of infection

Dental infections which may require the use of antibiotics include:

• Pericoronitis.
• Acute dentoalveolar infection.
• Lateral periodontal abscess.
• Acute ulcerative gingivitis.

The principles that govern management of infection argue that it is not essential to prescribe an antimicrobial routinely for dental infection. The initial assessment of an infection is important; this permits the clinician to assess the patient for signs of spreading uncontrolled infection and consider the need for prescription of antibiotics and/or hospital referral. The features which indicate uncontrolled infection are:

• Grossly elevated temperature, lethargy, tachycardia (indications of septicaemia).
• Spreading cellulitis.
• Swelling involving the floor of mouth which may compromise the airway.
• Difficulty in swallowing.
• Dehydration.
• Failure to respond to treatment.

The treatment process in the management of dental infection should be:

• Identify the cause of infection.
• Define the extent of the spread of infection.
• Record the temperature (normal 36.5 °C).
• Establish drainage and where possible eliminate the cause of infection.
• Consider taking microbiological samples to determine the antibiotic sensitivity of infecting organisms.
• Ensure the patient drinks plenty of fluid to remain hydrated.
• In the event that it is not possible to obtain drainage and the patient’s condition is worsening, seek specialist advice.

When antibiotics are considered as an adjunct to the management of dental infection, it is important to review the patient 2–3 days after prescribing to ensure resolution has occurred.

Amoxicillin, 250 mg three times per day, for up to 5 days, is the drug of first choice. Alternatives are amoxicillin, 3 g as two doses 8 hours apart, or phenoxymethylpenicillin, 500 mg four times per day for up to 5 days. Metronidazole, 200 mg three times a day for up to a maximum of 3 days, is an alternative drug, indicated in particular for anaerobic infections. Erythromycin, 250 mg four times a day for a maximum of 5 days, or 0.5–1 g every 12 hours, is a further alternative.

Antimicrobials in periodontal therapy

Systemic administration

Given that gingivitis and periodontitis are for the most part plaque-induced diseases, rarely associated with systemic disorders, it is not surprising that a great deal of research has been undertaken to assess the role of systemic antimicrobials in the management of periodontal diseases.

The use of a systemic drug has not been shown to give any long-term benefits in the management of chronic periodontitis. Chronic periodontitis is characterised by poor oral hygiene and a complex, Gram-negative anaerobic microflora. Microorganisms, often commensal in the mouth, elicit local opportunistic infection in an otherwise healthy patient. The variation in site and rate of progression of disease may be explained by the virulence of the microorganisms, the toxicity of their metabolic by-products and, in addition, the considerable individual host variation in defensive reaction.

Systemic antimicrobials should be reserved for that small proportion of patients who have aggressive forms of periodontitis. This is characterised by low plaque and calculus levels in conjunction with either local or generalised rapid and extensive loss of connective tissue attachment and a failure to respond to conventional non-surgical therapy. The microbial flora in this type of periodontitis is considered to be more aggressive and has a high proportion of periodontal pathogenic species. The use of systemic adjunctive antimicrobial therapy as part of an intense non-surgical programme of care can be beneficial.

Tetracycline is considered a useful drug since not only is it antibacterial but, in addition, it reduces host-mediated bystander damage and enhances tissue healing. Alternatives include a combination of metronidazole with amoxicillin. The use of low-dose long-term tetracycline has been advocated for patients with aggressive periodontitis but there are concerns regarding the risk of the emergence of bacterial drug resistance within the oral flora. The recognised periodontal pathogens are present not only in deep pockets but also in the saliva, on the tongue, palate and other non-pocket sites. These bacterial reservoirs can reinfect treated pockets, hence the indication for a systemic antimicrobial drug to eliminate the whole oral environment of periodontal pathogens.

Topical administration

It is recognised that local pocket response may vary in chronic periodontitis, dependent upon factors including pocket depth, root morphology, furcation involvement and operator skill. A range of topical antimicrobial agents has been developed for specific use in the management of local pockets which have failed to respond to root surface debridement.

Local antimicrobial delivery systems should only be considered as an adjunctive treatment, not an alternative to instrumentation. Thorough debridement should precede any consideration of local therapy. It is important to follow instructions in the product literature carefully at all times.

Topical antibiotics agents lack substantivity as they are washed out of the pocket by the flow of crevicular fluid and so repeated application may be required. An alternative to topical antibiotics is the use of biodegradable gelatin shields containing chlorhexidine which maintain antibacterial levels of the active agent for 10 days.

Current guidance on prophylaxis against infective endocarditis

Antimicrobial prophylaxis is the prevention of infection by the administration of antimicrobial agents. In principle, the administration of antimicrobial drugs should reduce morbidity and mortality. The issue is by no means clear in relation to the indications for and efficacy of the prophylactic use of antibiotics in dentistry. The incidence of infective endocarditis was and remained low despite the widespread use of antibiotic prophylaxis until recent times. It has been estimated that more people have been subject to damage as a result of adverse effects from the use of prophylactic antibiotics than have been prevented from developing infective endocarditis.

Historically in order to deliver a protective effect, prophylactic antibiotics were administered pre-operatively and time allowed for drug concentration in tissues to reach a therapeutic level prior to invasive dental treatment. Antibiotic prophylaxis was in the past routinely provided for patients deemed to be at risk of infective endocarditis.

Predisposing medical conditions and infective endocarditis

Infective endocarditis is a condition resulting from inflammation of the endocardium. The heart valves are especially at risk of damage. The infection is generally caused by bacteria (streptococci, Staphylococcus aureus and enterococci) but on occasion viral and fungal organisms can be associated with infective endocarditis. A rare condition with an annual incidence of 10 cases in a normal population of 100 000 infective endocarditis is, however, a serious life-threatening condition with a significant (20%) risk of mortality and morbidity.

Patients at risk of infective endocarditis include some, but not all, patients with a history of rheumatic fever who as a consequence may go on to develop heart valve damage. A cardiology assessment is required to confirm whether or not valve damage is present.

In the past, immunocompromised, renal dialysis and transplant patients were recommended to have prophylaxis. The Working Party of the British Society for Antimicrobial Chemotherapy (BSAC) advise that immunosuppressed patients (including transplant patients) and those with indwelling intraperitoneal catheters do not require antibiotic prophylaxis for dental treatment. Similarly the Working Party advised that patients with a prosthetic joint implant (including total hip replacement) do not require antibiotic prophylaxis for invasive dental procedures. Joint infections have rarely been shown to follow dental procedures and are even more rarely caused by oral streptococci. It is considered that it is unacceptable to expose patients to the adverse effects of antibiotics when there is no evidence that such prophylaxis is of any benefit. The advice is that patients who develop any infection require prompt treatment with antibiotics to which the infecting organism is sensitive.

Principles of treatment planning related to risk of infective endocarditis

Clinicians are expected to be familiar with and follow current clinical guidelines in relation to prophylaxis against endocarditis. It is vital to keep updated throughout your career as guidance may change.

National Institute for Health and Clinical Excellence (NICE) clinical guideline 64 ‘Prophylaxis against infective endocarditis’ provides a framework for decision making. Healthcare professionals are however required to use the guidance in conjunction with clinical judgment when deciding on the care of individual patients. The recommendations made by the guideline are based upon a review of current evidence and literature. The removal of recommendation to provide antibiotic prophylaxis for patients who are known to be at risk of infective endocarditis recognizes that the incidence of infective endocarditis is not reduced by large-scale use of antibiotics and the antibiotics themselves are thought to cause more risk of harm to patients in terms of allergic reaction. Antibiotic prophylaxis does not completely eliminate bacteraemia following dental procedures although it has been shown to reduce the frequency of detecting bacteraemia after dental treatment. Patients at risk of infective endocarditis are best served by the introduction of preventive strategies to maintain oral health. These include oral hygiene instruction, dietary advice, fissure sealing and fluoride supplements. Patients benefit from regular assessment and reinforcement of oral health education.

Clinical Guideline recommendations

The 2008 NICE guidance recommends that healthcare professionals should continue to consider people with some cardiac conditions as being at risk of developing infective endocarditis. These include:

• Acquired valvular heart disease with stenosis or regurgitation.
• Valve replacement.
• Structural congenital heart disease, including surgically corrected or palliated structural conditions, but excluding isolated atrial septal defect, fully repaired ventricular septal defect or fully repaired patent ductus arteriosus and closure devices that are judged to be endothelialised.
• Previous infective endocarditis.
• Hypertrophic cardiomyopathy.

There will be many patients who have prior to 2008 been advised to routinely have antibiotic prophylaxis before dental treatment. It is important to communicate with this group and indeed all patients at risk of endocarditis in a clear and consistent manner. A strong emphasis on the need for prevention of dental diseases is vital.

Information provided to patients should include:

• The benefits and risks of antibiotic prophylaxis including an explanation of why antibiotic prophylaxis is no longer routinely recommended.
• The importance of prevention in avoiding dental and oral diseases.
• The symptoms that may indicate infective endocarditis and instruction as to how and when to seek expert advice.
• The inherent risks of undergoing invasive procedures, including non-medical procedures such as body piercing or tattooing.

It is important, that to reduce the risk of endocarditis developing, any episode of infection in a person at risk of developing infective endocarditis is investigated and treated promptly. Some invasive procedures involving the gastrointestinal and genitourinary tract where there is already suspected infection will still require antibiotic prophylaxis. In these cases drug selection requires an antibiotic which is effective against organisms known to cause infective endocarditis. It is best practice to ensure patients are examined, advised of the importance of oral health and rendered dentally fit prior to surgery for total hip replacement, commencing renal dialysis, organ transplant, endocardial surgery, chemotherapy and radiotherapy to the head and neck.

Chlorhexidine mouthwash

Chlorhexidine is an effective antibacterial mouthwash; however, when used as an oral rinse it does not significantly reduce the level of bacteraemia following invasive dental treatment. Therefore chlorhexidine mouthwash should not be offered as a form of prophylaxis against infective endocarditis.

The selection and administration of antibiotic prophylaxis

Should a medical practitioner make specific instruction that as an exception antibiotic prophylaxis for infective endocarditis be administered then specific principles must be followed. Before administering antibiotic prophylaxis, it is important to check that the patient has no history of allergy to the selected drug and that the same drug or other antibiotics have not been recently prescribed. The selected (bactericidal) antibiotic should be taken in the presence of a dentist, dental nurse, dental hygienist or therapist to ensure compliance.

Examples of suitable drug selection for invasive dental procedures in patients who have not received more than a single dose of penicillin in the previous month, is oral amoxicillin, 3 g 1 hour before the procedure. Patients who are either allergic to penicillin or who have received more than a single dose of a penicillin in the previous month should be prescribed oral clindamycin, 600 mg 1 hour before treatment.

For multistage procedures, a maximum of two single doses of penicillin may be given in a month; alternative drugs should be used for further treatment and the penicillin should not be used again for 3–4 months. If clindamycin is used, periodontal or other multistage procedures should not be repeated at intervals of less than 2 weeks.

The use of analgesics in dentistry

Analgesic use in dentistry includes the use of both oral and local agents. While the dental hygienist and therapist may not prescribe oral agents, they will frequently be required to treat patients who are using these drugs and should note this when recording medical histories and be aware of any potential effects of these drugs in relation to dental local analgesia and treatment. Prescribers should advise patients if treatment is likely to affect their ability to drive motor vehicles or manage machinery. This is especially important in relation to oral analgesics, which may also have a sedative effect. Patients should be warned that these effects are increased by alcohol.

Oral analgesics should be used judiciously as part of dental therapy. Analgesics offer only temporary relief from dental pain. A full investigation and diagnosis of the cause of pain should be undertaken. Dental pain of inflammatory origin will not be managed by oral analgesics alone. Pulpitis, apical infection, dry socket or pericoronitis are usually best managed by treating the local infection through drainage, endodontic treatment and other local measures. Where a patient has a raised temperature then paracetamol or ibuprofen are the analgesics of choice due to their antipyretic action.

Pain and discomfort associated with acute conditions of the oral mucosa (e.g. acute herpetic gingivostomatitis, erythema multiforme) may be managed using benzocaine mouthwash or spray. Non-steroidal anti-inflammatory drugs (NSAIDs) are fr/>

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