ACUPAN

Indications

• Moderate pain
• Postoperative pain
• Musculoskeletal pain
• Pain associated with cancer

Dosage

Children: Refer to the BNF for Children for specific paediatric dosing information.

Adults: The usual adult dose is 30 mg to 60 mg three times daily, with a maximum dose of 120 mg per day. The dose may be adjusted based on the severity of pain and patient response.

Mechanism of action

Nefopam acts as a serotonin-norepinephrine-dopamine reuptake inhibitor. It enhances the levels of these neurotransmitters in the synaptic cleft, which contributes to its analgesic effects. Additionally, nefopam has antinociceptive properties that are thought to involve the modulation of descending pain pathways in the central nervous system.

Pharmacodynamics

Nefopam exhibits analgesic properties that are comparable to those of non-steroidal anti-inflammatory drugs (NSAIDs) and weak opioids. Its effects are attributed to its action on multiple neurotransmitter systems, particularly serotonin, norepinephrine, and dopamine. Nefopam does not produce sedation or respiratory depression, which distinguishes it from traditional opioid analgesics.

Pharmacokinetics

Nefopam is well-absorbed following oral administration, with peak plasma concentrations typically achieved within 1 to 2 hours. It undergoes extensive metabolism in the liver, primarily through glucuronidation. The elimination half-life of nefopam is approximately 3 to 5 hours. The drug is primarily excreted in urine, with a significant portion of the dose being eliminated as metabolites rather than unchanged drug.

Contra-indications

• hypersensitivity to nefopam or any of its excipients
• severe hepatic impairment
• severe renal impairment
• concurrent use of monoamine oxidase inhibitors (MAOIs)

Adverse effects

• nausea
• vomiting
• dry mouth
• dizziness
• drowsiness
• tachycardia
• sweating
• palpitations
• hypotension

Interactions

• concurrent use with other central nervous system depressants may enhance sedation
• may interact with drugs that affect serotonin levels
• caution with antihypertensives due to potential hypotensive effects

Precautions

• use caution in patients with a history of seizures
• caution in patients with cardiovascular disorders
• consider potential for abuse and dependence

Pregnancy

Use in pregnancy only if clearly needed, due to limited data on safety.

Breast-feeding

Not recommended during breastfeeding, as it is not known if nefopam is excreted in human milk.

Storage

Store below 25 degrees Celsius. Protect from light.

Formulations

• tablets
• injection

Indications

• Moderate pain
• Mild to moderate pain
• Pyrexia

Dosage

Children: Refer to BNF for Children for specific dosing information, as no paediatric doses are provided in the BNF.

Adults: Initially 60 mg three times a day, adjusted according to response; usual dose 30–90 mg three times a day.

Mechanism of action

Nefopam hydrochloride acts primarily by inhibiting the reuptake of neurotransmitters such as serotonin, norepinephrine, and dopamine in the central nervous system. This modulation of neurotransmitter levels contributes to its analgesic effects. Additionally, it is proposed to exert its analgesic properties through a mechanism similar to that of tricyclic antidepressants, though the exact pathways remain less defined compared to traditional opioids.

Pharmacodynamics

Nefopam has been shown to provide analgesia without the sedative effects commonly associated with opioids. Its efficacy in pain relief is similar to that of non-opioid analgesics but offers a different side effect profile. It does not have any known anti-inflammatory effects, which separates it from traditional NSAIDs. The analgesic effect can be attributed to its ability to alter pain perception at the spinal and supraspinal levels.

Pharmacokinetics

Nefopam is well absorbed after oral administration, with peak plasma concentrations typically occurring within 1 to 2 hours. It is extensively distributed in body tissues, and the volume of distribution indicates a wide tissue distribution. The drug is metabolized in the liver, primarily through conjugation, and is excreted in urine, predominantly as metabolites. The half-life of nefopam ranges from 2 to 5 hours, and it is recommended to use caution in patients with hepatic or renal impairment, adjusting doses as necessary.

Contra-indications

• Convulsive disorders
• Myocardial infarction

Adverse effects

• Drowsiness
• Headache
• Hyperhidrosis
• Insomnia
• Tachycardia
• Blurred vision
• Vomiting
• Abdominal pain
• Angioedema
• Confusion
• Diarrhoea
• Dizziness
• Dry mouth
• Urine discolouration
• Syncope
• Tremor
• Urinary retention

Interactions

• CNS depressants (e.g., benzodiazepines)
• Methadone (increased respiratory depression risk)

Precautions

• Caution in elderly patients
• Caution in angle-closure glaucoma
• Caution in patients with urinary retention
• Caution in hepatic impairment
• Caution in renal impairment
• Monitor for respiratory depression and sedation, especially with dosage adjustments

Pregnancy

No information available-avoid unless no safer treatment.

Breast-feeding

No information available.

Storage

Store in a cool, dry place away from direct sunlight.

Formulations

• Nefopam hydrochloride 30 mg tablets