Pain Medicine and Anti-inflammatory Drugs in Dentistry
T.3 – Pain Medicine
Analgesics
Analgesics are symptomatic medications that decrease the perception of pain without affecting the underlying cause. They are divided into:
Opioid Analgesics
These medications act on the central nervous system (CNS) to alleviate severe pain.
Non-Opioid Analgesics
These medications act on the peripheral nervous system (PNS) and are the most commonly used in oral pathologies.
Non-Opioid Analgesics
They are divided into:
a) Nonsteroidal Anti-inflammatory Drugs (NSAIDs): e.g., Aspirin
b) Antipyretics: These have little or no anti-inflammatory activity.
Mechanisms of Action of NSAIDs
NSAIDs exert their analgesic and anti-inflammatory effects by inhibiting the synthesis of prostaglandins, which are mediators of pain and inflammation. They also inhibit the synthesis of the enzyme cyclooxygenase, which converts arachidonic acid into prostaglandins and thromboxanes. The analgesic activity of NSAIDs is of moderate intensity and is less than that of opioid analgesics. They are useful for dental pain, joint pain, muscle pain, headaches, and fever. Prostaglandins influence the increase in body temperature, and NSAIDs suppress this response.
Indications of NSAIDs
NSAIDs are indicated for treating mild to moderate pain.
Adverse Effects of NSAIDs
Chronic treatment with NSAIDs can cause erosions and ulcers in the gastric and duodenal mucosa. Side effects may include:
Gastritis
Heartburn
Diarrhea
Constipation
Dyspepsia (bad digestion)
Prolonged use can cause:
Renal toxicity
Hypersensitivity
Hematological reactions
Acetylsalicylic Acid (Aspirin)
Properties
Analgesic and antipyretic in doses of 0.5 to 2g orally.
Anti-inflammatory action in doses from 3g/24h.
Platelet antiaggregatory action, which appears even in small doses, by inhibition of platelet cyclooxygenase. Not recommended before and after dental treatment.
Action on uric acid secretion. At low doses (1g/24h) produces inhibition of secretion. In high doses (+3 g/24h) promotes it.
Pharmacokinetics of Aspirin
It is absorbed in the stomach and first part of the duodenum.
It has rapid spread and high capacity tissue binding proteins (80%).
Able to move to other weak acidic substances, such as antivitamins K.
Metabolism of Aspirin
Short half-life (15 min.) since it hydrolyzes very rapidly into:
a) Salicylic acid
b) Acetic acid
Dosage
Children: 50mg/kg/24h
Adults: 1 to 3g/24h
Presentation
Effervescent tablets
Soluble powders
Injectable solutions
Aspirin is also associated with other active ingredients:
Dolmen
Couldina
Fiorinal
Desenfriol
Unwanted Effects of Acetylsalicylic Acid
Heartburn
Microhemorrhages
Risk of gastroduodenal ulcers
Allergic manifestations: (Do not use in asthmatics)
Urticaria
Erythema
Anaphylactic shock
Blood dyscrasias: Due to antiplatelet action. Aspirin can be used to prevent thrombosis, the origin of cardiovascular and cerebral events.
Hemolytic anemia
In cases of overdose, symptoms include: Vertigo, tinnitus (hearing noises), dehydration, respiratory problems, convulsions, and coma. It is important to respect the doses and distribute them regularly during the day.
Contraindications
Gastroduodenal pathology
Blood dyscrasias
History of allergy to aspirin
Do not give aspirin to patients taking Sintrom (or other anticoagulants)
Antipyretics with Little or No Anti-inflammatory Activity
1) Paracetamol
Paracetamol is an analgesic and antipyretic that is effectively similar to aspirin but has no anti-inflammatory action.
Pharmacokinetics of Paracetamol
Rapid gastrointestinal absorption
Good tissue dissemination
Hepatic metabolism
Renal excretion
Presentation and Dosage
Available in the form of suppositories for infants, children, and adults.
Available in the form of powders, tablets, and injectables (e.g., Efferalgan, Termalgin).
Dosage
Children: 20mg/kg/24h (split into 3 or 4 doses)
Adults: 1 to 3 g/24h
Can be used in patients with hemophilia or bleeding, as it does not decrease platelet aggregation. Its main side effect is liver toxicity. It is the analgesic of choice for mild or moderate pain in children under 12 years to avoid Reye’s syndrome (a multisystemic disease that occurs in children under 12 years).
2) Metamizole (Dipyrone) (Nolotil)
Metamizole is a potent analgesic. A dose of 2g can match the effect of low doses of opioids. It acts on smooth muscle and is useful in colic pains. It is an effective analgesic in the treatment of moderate pain and is especially suited for intramuscular injection. It has strong antipyretic properties and little activity on the gastric mucosa and platelet aggregation.
Opioid Analgesics
Opium is obtained from the Asian poppy Papaver somniferum and contains several substances, the most important of which are morphine and codeine. Opioids have analgesic activity and act on specific receptors in the CNS. These painkillers can be:
Opium derivatives (morphine, codeine)
Synthetic (heroin, methadone, hydrocodone)
Opioid analgesics have a ceiling effect, meaning that the higher the dose, the greater the analgesia. In contrast, with non-opioids, exceeding a certain dose does not increase the analgesic effect.
Mode of Action of Opiates
Opioids interact with receptors in the brain and spinal cord to suppress pain sensation.
Classification of Opioids
Agonists: Morphine, Heroin, Codeine, Hydromorphone, Methadone, Fentanyl
Antagonists: Naloxone, Naltrexone
Antagonists block the action of the agonists.
Indications of Opioids
Opioid analgesics are indicated for the treatment of severe pain and some types of neuropathic pain. They produce selective analgesia without altering the state of consciousness, vision, or hearing. The duration of effect depends on:
Dose
Tolerance
Characteristics of pain
Personality of the patient
Adverse Effects
Morphine-type opiate agonists can cause:
Drowsiness
Euphoria
Miosis (pupil constriction)
Nausea and vomiting
Constipation
Dry mouth
Urinary retention
Sedation
Confusion
Acute intoxication with these drugs can produce convulsions, respiratory depression, and cardiovascular collapse. An overdose is treated with naloxone (antagonist).
Morphine
Properties
Analgesic effect
Produces euphoria and hallucinations
Effect on central respiratory system – Respiratory depression and antitussive action
Other effects: Constriction of the smooth muscle fibers of the sphincters (constipation), bronchoconstriction, miosis, nausea
Pharmacokinetics
Parenteral administration takes 4 hours to take effect.
Gastrointestinal absorption is irregular and varies according to individuals.
It is recommended that regular administration of morphine be in sweetened preparations, drinkable ampoules, or tablets (for severe pain in cancer patients).
Metabolism is hepatic, and elimination is via the bile and saliva.
Dosage
Dosage should be tailored to each patient.
Undesirable Effects
Nausea
Hypotension
Constipation
Respiratory depression
The most serious undesirable effect is drug dependence, as it is both psychological and physical. Abstinence syndrome can occur in cases of abrupt discontinuation. Tolerance leads to a dose increase to achieve the desired effect.
Codeine
Codeine is a natural alkaloid of opium with a structure similar to morphine. It is an antitussive and analgesic. It is often used in association with non-opioid analgesics, e.g., Termalgin Codeine.
The undesirable effects are very similar to those of morphine, the most important being constipation, bronchospasm, dizziness, nausea, and drowsiness.
Contraindications
Do not administer to patients with:
Respiratory failure
Pregnant or breastfeeding women
Children
T.3.b – Anti-inflammatory Drugs
Glucocorticoids (Suitable for Extractions)
Glucocorticoids inhibit prostaglandin synthesis at an earlier stage than NSAIDs and have an immunosuppressive effect. In dentistry, they have a very restricted use:
Prophylaxis of post-inflammation of 3rd molar extraction (impacted)
Autoimmune conditions (lupus, erosive lichen planus, etc.)
Allergic reactions (anaphylactic shock, edema of the glottis, etc.)
Drugs
Dexamethasone
Hydrocortisone
Prednisolone
Precautions for Use
In patients with ulcers, administer with a gastric protective.
Use in diabetic and hypertensive patients can be problematic, causing fluid and sodium retention.
May increase anticoagulant effects when given with aspirin, as it increases the level of acetylsalicylic acid in the blood, provoking salicylism.
Treatment should not be discontinued abruptly, as this can cause adrenal insufficiency.
Long-term treatments can result in psychiatric problems.
Contraindications
Absolute
Fungal infections (decrease defenses)
Hypersensitivity reactions to steroids
Relative
Diabetes, hypertension, osteoporosis, peptic ulcer, psychiatric history