Chapter 12

Therapeutics

Prescribing

The following pages are a brief guide to the clinical use of some of the more commonly used and useful drugs in hospital and general dental practice. Doses are for healthy adults.

Prescribing in general dental practice

Extremely useful information is available in the BNF, which is updated every 6 months. Use this as the first line of enquiry when unsure about any topic concerning drugs. Drugs listed in the DPF (found at the back of the BNF) can be prescribed in the UK within the NHS on form FP10 D (GP14 in Scotland, WP10 D in Wales, HS47 in Northern Ireland). Any other required drugs must be prescribed privately or via the patient’s GMP. Many are available more cheaply OTC at pharmacies.

Prescribing in hospital

The BNF is the definitive reference and should always be available for consultation. Use this to check dose alterations in children (BNF for Children) and the elderly, and for more detailed tables of drug interactions, C/I, and unwanted effects. Any drug in the hospital pharmacy may be prescribed by a hospital dentist for in-patients, patients being discharged, and out-patients. The only exception is controlled drugs for addicts, which must be prescribed by specially licensed doctors, usually a psychiatrist.

In hospitals, there are three methods of prescribing: (i) A hospital prescription chart recording both prescriptions and dispensing, kept on the ward for in-patients. (ii) A take-home prescription form redeemable only at the hospital pharmacy for patients being discharged from the ward. (iii) Hospital out-patient prescriptions, used in emergency departments and some out-patient clinics, redeemable at outside pharmacies.

Good prescribing

Avoid abbreviations and write drug names legibly, using the generic whenever possible. Always describe the strength and quantity to be dispensed. When describing doses, use the units micrograms, milligrams, or millilitres when possible. Do not abbreviate the term microgram or unit (when prescribing insulin) as these are easily misinterpreted.

Controlled drugs

Each prescription must show, in the prescriber’s own handwriting in ink: the name and address of the patient, the form, strength, dose, and total quantity of the drug to be dispensed, in both words and figures. When writing in general practice the prescription must also incorporate the phrase ‘for dental treatment only’.

Prescribing in the elderly

Doses may need adjustment and are often substantially lower than for adults (often 50% lower).

Prescribing for children

Children differ markedly from adults in their response to drugs, especially in the neonatal period when all doses should be calculated in relation to body weight. Older children can usually be prescribed for in age ranges, usually up to 1yr, 1–6yrs, and 6–12yrs. All details of dosages should be checked in the BNF or BNF for Children.

Prescribing in liver disease

(p. 498) As most drugs rely on hepatic metabolism, it is prudent to seek medical advice before prescribing for patients with severe liver disease.

Prescribing in renal impairment

(p. 500) Doses almost always need to be ↓ and some drugs are C/I completely. Medical advice should be sought.

Prescribing in pregnancy

(p. 504) Avoid if possible.

Prescribing in terminal care,

p. 546.

Dose and route abbreviations:

Analgesics in general dental practice

Consult BNF for dosages in children. See also p. 558. Most dental pain is inflammatory in origin and hence most responsive to drugs with an anti-inflammatory component, e.g. aspirin and the NSAIDs.

Of the peripherally acting analgesics in the DPF, aspirin, paracetamol, and ibuprofen are available cheaper direct to the public from pharmacies.

Aspirin

Used in mild to moderate pain, it is also a potent antipyretic, which should not be used in children <12yrs (due to the rare but serious risk of Reye syndrome). Avoid in bleeding diathesis, gastrointestinal ulceration, and concurrent anticoagulant therapy. Ask about aspirin allergy, particularly in asthmatics. Often causes transient gut irritation (as do all NSAIDs). Dose: 600–900mg 4 hourly PO. Topical sakylate gels are now C/1<16.

Ibuprofen

Popularly used for mild to moderate pain; has a moderate antipyretic action. Risks and side-effects are similar to those of aspirin but less irritant to the gut. Dose: 400–600mg 8 hourly PO.

Paracetamol

Similar in analgesic efficacy to aspirin but has no anti-inflammatory action and is a moderate antipyretic. Does not cause gastric irritation or interfere with bleeding times. Overdosage can lead to liver failure. Dose: 1000mg 6 hourly PO (maximum dose 4g/24 hours in adults).

Diflunisal

A prescription-only drug available on the DPF, with similar properties and problems to aspirin. Dose: 250–500mg bd with food PO.

The addition of codeine to the minor analgesics, while never being proven to be of advantage, may have marginal benefits in some cases. No combination analgesics are currently prescribable on the DPF.

There are very few indications for the use of opioid analgesics in general dental practice. Although dihydrocodeine remains in the DPF it has been demonstrated to be hyperalgesic in certain types of dental pain.¹

Pethidine

In tablet form (the only form in the DPF), is worse than dihydrocodeine in terms of side-effects.

Carbamezipine

(p. 576) Prescribable in the DPF.

NB While all NSAIDs may exacerbate asthma and there is a higher incidence of NSAID allergy in asthmatics, the CSM recognizes that this does not constitute a C/I for the use of these valuable analgesics. Frank allergy to NSAIDs or proven exacerbation of asthma is a C/I.

Analgesics in hospital practice

In addition to those available in the DPF, some drugs available only within hospitals are of considerable value.

Diclofenac sodium

is available in tablet, IM injection, suppository, and in once-daily, slow-release form. It is a mid-potency NSAID, and a useful alternative to high-dose lower potency NSAIDs or an opioid which has no anti-inflammatory effect. Dose for tablets: 50mg tds after food; IM injection: 75mg bd for no more than 2 days (it’s a painful injection); suppositories: 100mg PR od. Soluble tablets are available.

Ketorolac trometamol

30mg/ml injection has advantage of small volume of injection. However ↑ unwanted effects have been noted and it is no longer recommended for general use.

Opioid analgesics

The opioids act centrally to alter the perception of pain, but have no anti-inflammatory properties. They are of value for severe pain of visceral origin, post-op (acting partly by sedation), and in terminal care. However, they all depress respiratory function and interfere with the pupillary response, and are C/I in head injury. All opioids cause cough suppression, urinary retention, nausea, constipation by a ↓ in gut motility, and tolerance and dependence. The risk of addiction is, however, greatly overstated when these drugs are used for short-term post-op analgesia and in the terminal care context. Fear of creating addicts should never cause you to withhold adequate analgesia.

Codeine phosphate

A moderate opioid analgesic useful for short-term analgesia and less likely to mask a head injury; 30–60mg 4 hourly IM/PO. May be some advantage when used in combination (8/15/30mg) with simple analgesics or NSAIDs.

Morphine

In oral form (tablets, elixir, or slow-release tablets MST), the drug of choice in the management of terminal pain. Always prescribe a laxative (macrogols are currently in favour: see BNF). Dose: dependent on previous analgesia, but often starts at 10mg morphine 4 hourly or 30mg MST bd. When used IM or IV for acute or post-op pain: 10–20mg 2–4 hourly; give an antiemetic.

Papaveretum

A mixed opium alkaloid, frequently prescribed, but appearing to have no advantage over morphine. The presence of noscapine created a C/I in women of childbearing age. Noscapine-free equivalent (Omnopon® 10 + 20). Neither of these is in general use currently in UK.

Buprenorphine

A mixed agonist/antagonist with similar problems to pethidine and pentazocine. Unique in that it can be given sublingually. Dose: 200–400μg 8 hourly. This is often used in opioid withdrawal.

Diamorphine

(heroin) A very potent opioid which should be reserved for severe pain in an in-patient setting. Like morphine it is reversed by naloxone. Dose 1–2mg IV with appropriate patient monitoring.

Tramadol

An opioid which acts by two central methods. Lower side-effect profile. 50–100mg PO 4 hourly. Slow IV 50–100mg 4–6 hourly.

Chronic and post-op pain require regular, not as-required, analgesia, given in adequate amounts and within the therapeutic half-life of the drug.

PCA

(p. 546) A computerized system for post-op pain control allowing patients to deliver small regular doses of IV/SC morphine/diamorphine. Gold standard post-op analgesia for severe pain.

Anti-inflammatory drugs

These are among the groups of drugs that may be either analgesics or co-analgesics (drugs which are not analgesic in themselves but may aid pain relief either directly or indirectly). The two major groups are the NSAIDs (p. 560) and the corticosteroids.

Steroids are used in various forms, topical, oral, intralesional, and parenteral, and all have uses in dentistry.

Topical steroids

Hydrocortisone lozenges

2.5mg lozenges dissolved in the mouth qds.

Triamcinolone in carboxymethylcellulose paste

0.1% paste applied in a thin layer qds. Sticks only to dry mucosa and is rapidly rubbed off the palate and tip of tongue. Both these preparations are available in the DPF and are of use in the management of recurrent apthous ulcers, lichen planus, />