Analgesics: Non-Opioid and Opioid Medications
Non-Opioid Analgesics
There is a correlation between dosage and distribution throughout the day.
Contraindications:
- Gastroduodenal Pathology
- Blood Dyscrasias
- History of allergy to aspirin
Antipyretics with Little or No Anti-inflammatory Activity
1. Paracetamol: An analgesic and antipyretic with efficacy similar to that of Aspirin, but without anti-inflammatory action.
Pharmacokinetics
- Rapid gastrointestinal absorption. Peak serum concentrations are attained within 45 minutes.
- Good Histic diffusion (of fabrics)
- Hepatic Metabolism
- Renal Elimination
Presentation and Dosage
Available in the form of suppositories for infants, children, and adults (e.g., Eferalgan, Termalgin).
Dose
- Children: 20mg/kg every 24 hours, distributed in 3 or 4 doses.
- Adults: 1 to 3 grams every 24 hours.
Paracetamol can be used in patients with Hemophilia or bleeding, as it does not decrease platelet aggregation. Its main adverse effect is liver toxicity. It is the painkiller of choice for mild or moderate pain in children younger than 12 years to avoid Reye’s syndrome.
2. Dipyrone or Metamizole (Nolotil): A potent analgesic. A dose of 2 grams can match the effect of low doses of opioids. It acts on smooth muscle, making it useful for cramping pains. It is an effective analgesic in the treatment of moderate pain and is particularly useful intramuscularly. It also has great antipyretic activity. It has little activity on the gastric mucosa and platelet aggregation.
Opioid Analgesics
Opium is obtained from the Asian poppy Papaver and contains various substances, including:
- Morphine
- Codeine
Opioid analgesics are a large group of drugs with analgesic activity and pathways and specific receptors in the CNS. They are derived from opium (morphine, codeine) or are synthetic, such as heroin, methadone, etc.
The main difference is that non-opioid analgesics have an analgesic ceiling; that is, the higher the dose, the greater the analgesia. Opioids, above a certain dose, do not achieve a greater analgesic effect.
Mode of Action
In the brain and spinal cord, there are receptors for pain. Opioids interact with these to suppress pain sensation.
Classification
Adrenergic agonists and antagonists act as a type of opioid receptor, and an antagonist against another blocks the action of morphine.
Agonists:
- Morphine
- Heroin
- Codeine
- Meperidine
- Methadone
- Fentanyl
Antagonists:
- Naloxone
- Naltrexone
Indications
In dentistry, they are indicated in 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 effective analgesia depends on:
- Dose
- Tolerance (prior experience with opiates)
- Characteristics of pain
- Personality of the patient
Therefore, the optimal dose will depend on the individual characteristics of each patient.
Adverse Effects
Opiates like morphine can cause:
- Drowsiness
- Euphoria
- Miosis
- Feelings of shame
- Nausea
- Vomiting
- Constipation
- Dry mouth
- Urinary retention
- Sedation
- Confusion
Acute poisoning can cause seizures, respiratory depression, etc.
Morphine
Properties
- Effect on pain
- Produces feelings of euphoria and hallucinations
- Effect on the respiratory centers: antitussive action, respiratory depression