Drugs

  • Drugs alter cell activity and can be used to prevent a condition(prophylactic) or to control a condition (therapeutic).
  • These can be administered externally (topically) or internally (systemically)

Routes of Administration

  • Orally is administered by mouth and absorbed through the normal digestive route.
  • Intravenous is administered directly into blood stream which has an immediate effect
  • Inhalation means to be inhaled into the blood stream.
  • Topical is applied to surface of skin or mucosa, such as steroid creams and topical anaesthetic.
  • Intramuscular is administered into muscle tissue and into the blood stream. This produces rapid results.

Absorption of Drugs

  • Liver enzymes metabolise some of the drug and only part of the ingested drug reaches its intended tissues (by plasma). The part of the drug metabolized (broken down) by the liver and the inactive substances are excreted by the kidneys into urine.
  • Stomach absorbs alcohol, certain medicines, caffeine and water (only if dehydration is present)
  • Some drugs pass through the placental barrier and can have an effect on the foetuseg. Thalidomide used to be given for morning sickness causing limb deformities

Classification

  • Drugs are classified by their specific functions. Classifications are as follows:

Anti-microbials - Management of Micro-Organisms

Anantimicrobialis an agent that killsmicro-organismsor inhibits their growth. Antimicrobial medicines can be grouped according to the microorganisms they act primarily against.

Disinfectant

  • An externally used agent that reduces number of pathogens to safe levels.
  • Sodium hypochloriteis a bleach solution - used to irrigate root canals (Milton). Effective against HepB and HIV. Impression disinfectant such as ‘Perform’ is another example.

Antiseptics

  • Disinfectants applied to human skin
  • Chlorhexidine. Also considered an antibacterial. 0.2% mouthwash (Corsodyl) that inhibits plaque formation. Also presents in a 1% gel used to inhibit plaque formation in a localised area. A disadvantage of this product is the terrible staining, so it should not be used for any longer than 2 weeks. Chlorhexidine can be incompatible with some toothpaste ingredients. This is why it is recommended to use the mouthwash at least 30 minutes after brushing.
  • Hydrogen peroxide – 3% solution for irrigation of dry sockets. Can be diluted to 0.5% as a breath freshener and cleansing mouthwash for NUG. Also found in some whitening kits.
  • Iodine can be applied to the skin surface prior to injection. It stains skin brown. It can also be used to irrigate infected sockets. This is a dated method and allergy is prevalent.

Antibiotics / Anti-bacterial drugs

  • Drug used to treat bacterial infections
  • Bacteriocidal agents kill bacteria
  • Bacteriostatic agents inhibit the growth of bacteria
  • Each course must be completed or it will not have its effect
  • If any signs of allergy, stop immediately and consult doctor
  • Antibacterial drugs are anti-biotics (aerobic bacteria) and anti-microbials (anaerobic)

Penicillin

  • An antibiotic and was discovered by Professor Alexander Fleming in 1928.
  • Derived from microbes and moulds. Overuse can cause immunity to the antibiotic as resistant strains of the bacteria develop against the drugs.
  • It is bacteriocidal and destroys mostly aerobic microbes.
  • Can be used to prevent spread of pericoronitis, cellulitis (bacterial infection involving the skin) and may be used after MOS to prevent secondary infection.
  • Contraindications include patients taking methotrexate (for some cancers and psoriasis) as it clears the effects. Penicillin allergy is common.

Amoxicillin

  • A derivative of penicillin and has a wider range action. These are helpful with infections that do not respond to penicillin. This drug is known to be better absorbed than penicillin.
  • Note that broad spectrum antibiotics can increase the risk of C. Diff if used regularly.

Erythromycin

  • A microlide antibiotic with awider spectrum than penicillin. These can be used with patients who are allergic to penicillin or penicillin resistant infections. This drug can increase the anticoagulant effect of warfarin and should not be given to patients on statins (drug which reduces cholesterol).

Clindamycin

  • Active against gram positive cocci. Not used routinely, but can be prescribed if infection has not responded to penicillin or Metronidazole.

Doxycycline

  • A tetracycline based antibiotic commonly prescribed for sinusitis. Caution should be shown with patients with hepatic impairment (liver) or hepatotoxic drugs (cause damage to the liver). No pregnant women, nursing mothers or kids under 12 as it can deposit on growing bone and teeth causing staining or hypoplasia. Taking this drug may enhance the anti coagulant effect of warfarin.

Metronidazole

  • Can be used to treat NUG and periocoronitis.
  • Can be used alongside amoxicillin if infection is spreading.
  • This is a safe alternative for patients with penicillin allergies. The body is not at risk of building a resistance to these drugs.
  • Contraindications include patients on cyclosporine, statins or some anti-epileptic drugs.
  • Do not give during pregnancy or breast feeding.
  • This drug can increase the anticoagulant effect of warfarin.
  • Metronidazole is believed to have the ability to block the body’s breakdown of alcohol, leading to the accumulation of a substance calledaldehyde in the blood stream. Symptoms include nausea and vomiting.

Antifungal Drugs

  • Used to treat fungal infections
  • Work by exploiting differences between human and fungal cells to kill the fungal organism without dangerous effects on the host. Human and fungal cells similar so it is more difficult to find or design drugs that target fungi, without affecting human cells.
  • Used to treat candidosis, denture stomatitis, thrush, angular chelitis
  • Contraindications are that they should not be taken during pregnancy or breast feeding or patients taking anticoagulants (patients taking warfarin or statins).
  • Examples - fluconazole capsules,miconazoleoromucosal gel,nystatin, Amphotericin lozenges

Antiviral Drugs

  • Viruses tend not to respond to drug treatments as they are able to mutate to suit their environment.
  • They work by blocking the multiplication of the virus to stop it progressing to the next stage. The virus will not be destroyed by the drug.
  • Acyclovir can be used to treat varicella-zoster (chicken pox) and herpes simplex of the skin and mucous membrane.
  • Penciclovir used to treat herpes simplex labialis (cold sore)

Analgesic Drugs

  • Drugs that relieve pain (painkillers)
  • Mild analgesics include aspirin, certain codeine preparations and paracetamol and require no prescription
  • Medium analgesics include dihydrocodeine and a prescription is required
  • Powerful analgesics include morphine and pethidine

Eugenol

  • Oil of cloves – external application
  • Mixed with zinc oxide to make an analgesic cement
  • Used after gingivectomy and to dress cavities
  • Allergy prevelant

Paracetamol

  • Antipyretic which means it reduces fever
  • Has anti inflammatory properties
  • This drug metabolises in the liver and is toxic to this organ in the event of overdose.
  • Low risk of addiction
  • Alcohol increases toxicity of paracetamol
  • Increased use in suicides - regulations allow only 32 to be purchased at any one time
  • Has less side effects thanNSAID’s

Opioid Analgesic - Codeine

  • An opioidaffects the central nervous system and gives the perception of decreased pain.
  • Codeine is a weak opioid analgesic and suppresses coughs and diarrhea
  • Repeated administration can cause dependence and tolerance.
  • Combining an opioid drug with a non opioid can provide greater pain relief.
  • Co-codamol is codeine combined with paracetamol. High strengths are prescription only. Lower strength preparations are available over the counter such as Solpadine.

Anti Inflammatory

  • Corticosteroids relieve pain
  • Corticosteroids combined with an antibacterial drug can be used to suppress inflammation. An example of this is Ledermix
  • Corticosteroids are natural hormones produced in the adrenal glands in times of stress – taking them in drug form can suppress natural production. If there is no production of hormones that help us deal with stress – hypotension and collapse may occur. Patients on steroids are given ‘steroid cover’ to combat this problem.

NSAIDs

  • Non-Steroidal Anti-Inflammatory Drugs (NSAID’s) are analgesics with anti inflammatory properties. These work by affecting specific hormone that produces inflammation. Unfortunately these are the same hormones that help protect the stomach and ulceration may occur in stomach and intestine.
  • All NSAID’S are contra-indicated in severe heart failure, peptic and gastric ulcers.
  • NSAID’s should not be used for analgesia in patients taking warfarin.

Aspirin

  • Toothache and post operative pain,
  • Anti platelet ingredient thins blood – anti coagulant
  • Children under 16 – no aspirin – Reyes syndrome – brain disease
  • Not suitable during pregnancy or breast feeding
  • Main effects are gastro-intestinal distress – ulcers, bleeding, tinnitus
  • Aspirin decomposes by moisture
  • Allows blood to thin and run easier – lack of oxygen to the heart causes chest pain (myocardial infarction / angina)
  • Discuss aspirin burn

Ibuprofen

  • Anti inflammatory, analgesic and antipyretic properties
  • May reduce blood pressure
  • Asthma sufferers may experience more of an allergic reaction, rash swelling, difficulty in breathing
  • Not suitable during pregnancy or breast feeding

Difflam

  • Benzydamine hydrochloride
  • Used for painful conditions of the oro-pharynx, ulcers, post surgery.
  • Presented in oral rinse or spray

Care of Drugs

  • Keep away from foods and drinks
  • Keep poisons in a locked cupboard (COSHH) also prescription pads, syringes and needles.
  • Log books, records must be kept for 11 years, purchase, supply, expiry date
  • Poisons have a ribbed bottle to indicate poisons
  • All drugs must be carefully labeled, name of drug, dosage, amount
  • Talk about consequences of wrong labeling
  • Moisture changes chemical action of some drugs
  • Heat causes quicker deterioration
  • Store in a cool dry place

Dispensing

  • Childproof containers
  • Manufacturer’s instructions
  • Labeled with drug, dosage, amount, name of patient, directions, precautions for use, dentist name and address

Disposal

  • Return to pharmacy
  • Return to manufacturer

Misuse of Drugs Act

  • Categorises drugs into classes A,B,C – Class A demands a bigger criminal penalty than class C

Misuse of Drugs Regulations 2001

  • Defines the classes of persons allowed to prescribe, possess, supply and manufacture drugs while acting in their professional capacity

Drugs that Impact Dentistry

The following is small representation of drugs that interact with dental treatment.

Bisphosphonates

  • Drugs used to prevent the loss of bone mass. Used to treat osteoporosis and cystic fibrosis. Cancer patients may take them to protect bones and reduce raised calcium levels in blood. Work by inhibiting osteoclasts (bone destroying cells). Taking any bisphosphonate may cause osteonecrosis of the jaw. The jaw has a high turnover of bone and bisphosphonates accumulate here. This may reduce bone turnover and blood supply which may lead to death of the bone. This is discussed in oral disease.

Statins (Simvastatin)

  • Reduce cholesterol
  • Unable to take some antifungal preparations

Warfarin

  • Anticoagulant drug
  • Contraindications include antifungal preparation, NSAID’s, Metronidazole and some antibiotics as noted in relevant section. Penicillin and tetracycline fine for these patients.
  • Patients undergoing oral surgery must have INR checked prior to treatment.
  • INR means international normalized ratio. This is a measurement of blood coagulation. INR 5 means high chance of bleeding. INR 0.5 means high chance of clotting. A healthy person should be approximately 0.9 – 1.3. Someone on Warfarin is typically 2.0 – 3.0

Diuretic

  • Diuretics are medicines that remove water from the body by increasing the amount of urine the kidneys produce.
  • They are often known as 'water tablets' because they remove excess water.
  • The most common reasons you may need to take a diuretic are if you have: high blood pressure or too much fluid in the tissues of your body (this is known as oedema), as a result of heart failure (which is when your heart loses its ability to pump blood efficiently throughout your body).
  • May cause xerostomia.

Beta Blocker (Atenolol)

  • Medicationused to treat several conditions, often by decreasing heart activity.
  • They work by blocking the release adrenaline in certain parts of the body.
  • Beta-blockersmay be used to treat: Angina, heart failure (where the heart does not pump blood around the body effectively, arterial fibrillation(irregular heartbeat), myocardial infarction and hypertension(high blood pressure).
  • May cause xerostomia, salivary gland swelling and gingival hyperplasia.
  • NSAID’s can impair the effect of beta blockers

Phenytoin – Epanutin

  • Anti epileptic drug
  • Increase in the risk of gingival hyperplasia.

Methotrexate

  • Used to treatautoimmune diseasessuch asrheumatoid arthritis,psoriasis,andCrohn's disease. Also a chemotherapy drug in high doses.
  • Can cause oral ulceration.
  • Patients should also be advised to avoid NSAID’s and penicillin as they increase the risk of toxicity. Nitrous oxide inhalational sedation should also be avoided.Patients on this drug should not be given aspirin as it may enhance toxicity.

Ciclosporin

  • Immunosuppressant drug used to prevent rejection of transplant organs.
  • Increase in the risk of periodontal disease and gingival hyperplasia

Nifedipine

  • To treat angina and high blood pressure (hypertension)
  • Increase in the risk of periodontal disease and gingival hyperplasia

Thyroxine

  • A hormone produced by the thyroid gland that keeps your metabolism working at the correct pace.
  • Many cells and tissues in the body need thyroxine to keep them functioning correctly.
  • Hypothyroidism is a condition in which the thyroid gland does not make enough thyroxine.
  • Levothyroxine (thyroxine) tablets are given to patients with this condition to replace what the body can’t produce.
  • The effects of epinephrine may be intensified by this drug – caution should be exercised when using Lidocaine local anaesthetic preparations.

Xerostomia

  • Dry mouth
  • Sufferers are at risk of increase in caries and periodontal disease. Tolerance of dentures will be difficult.
  • Drugs which may cause xerostomia are: Beta Blockers, tricyclic antidepressants, antipsychotic drugs, diuretics and radiotherapy.
  • Lozenges, sprays, gels, pastilles and tablets available to help with the condition, but there is little relief from substitute saliva.
  • Increase fluid intake and fluoride therapy advised.