Local anaesthesia

Local anaesthesia

Local anaesthetic drugs act by causing a reversible block to conduction along nerve fibres. The drugs used vary widely in their potency, toxicity, duration of action, stability, solubility in water, and ability to penetrate mucous membranes. These variations determine their suitability for use by various routes, e.g. topical (surface), infiltration, peripheral nerve block, intravenous regional anaesthesia (Bier’s block), plexus, epidural (extradural) or spinal block. Local anaesthetics may also be used for postoperative pain relief, thereby reducing the need for analgesics such as opioids.

LIDOCAINE HYDROCHLORIDE (Lignocaine hydrochloride):

Indications: Lignocaine is used as a local anaesthetic in infiltration field block, nerve block and spinal anaesthesia. As a local anaesthetic it has an action of intermediate duration, which can be increased by adding adrenaline.

Contraindications: Contra-indicated in patients that are hypersensitive to local anaesthetics. Lignocaine hydrochloride should not be given to patients with hypovolaemia, heartblock or other conduction disturbances, bradycardia, cardiac decompensation or hypotension unrelated to treatable tachyarrhythmias, myasthenia gravis.

Dose and Administration: Infiltration anaesthesia, by injection, according to patient’s weight and nature of procedure, max. 200 mg. Surface anaesthesia, usual strengths 2–4%.

Lidocaine hydrochloride 5% Ointment:

Dose: Dental practice, rub gently into dry gum, Sore nipples from breast-feeding, apply using gauze and wash off immediately before feed. Pain relief (in anal fissures, haemorrhoids, pruritus ani, pruritus vulvae, herpes zoster, or herpes labialis), 1–2 mL applied when necessary; avoid long-term use.

Lidocaine hydrochloride 10% Spray:

Dose: Dental practice, 1–5 doses. Maxillary sinus puncture, 3 doses. During delivery in obstetrics, up to 20 doses. Bronchoscopy, laryngoscopy, oesophagoscopy, endotracheal intubation, up to 20 doses; child up to 3 mg/kg.

LIDOCAINE-PRILOCAINE:

Indications: indicated for local anaesthesia – on intact skin prior to minor dermatological procedures (e.g. needle insertion and surgical treatment of localised lesions) and prior to dermal procedures on larger areas e.g. split skin grafting. – on genital mucosa prior to surgical treatment of localised lesions. In term newborn infants and children under the age of 18 years, it is indicated for local anaesthesia on intact skin prior to minor dermatological procedures.

Contraindications: Known hypersensitivity to anaesthetics of the amide type or to any other component of the product.

Dose and Administration: Anaesthesia before minor skin procedures including venepuncture, apply thick layer under occlusive dressing 1–5 hours before procedure (2–5 hours before procedures on large areas e.g. split skin grafting); infant 1–12 months single application on intact skin under specialist supervision, under 1 month not recommended. Anaesthesia before removal of warts from genital mucosa in adults, apply up to 10 g 5–10 minutes before removal.

BUPIVACAINE HYDROCHLORIDE:

Indications: Intrathecal (subarachnoid) spinal anaesthesia for surgery (urological and lower limb surgery lasting 2–3 hours, abdominal surgery lasting 45–60 minutes). Bupivacaine is a long-acting anaesthetic agent of the amide type. Marcain Heavy has a rapid onset of action and long duration. The duration of analgesia in the T10–T12 segments is 2–3 hours.

Marcain Heavy produces a moderate muscular relaxation of the lower extremities lasting 2–2.5 hours. The motor blockade of the abdominal muscles makes the solution suitable for performance of abdominal surgery lasting 45–60 minutes. The duration of the motor blockade does not exceed the duration of analgesia. The cardiovascular effects of Marcain Heavy are similar or less than those seen with other spinal agents.

Contraindications: Hypersensitivity to local anaesthetics of the amide type or to any of the excipients. Intrathecal anaesthesia, regardless of the local anaesthetic used, has its own contraindications, which include: Active disease of the central nervous system such as meningitis, poliomyelitis, intracranial haemorrhage, sub-acute combined degeneration of the cord due to pernicious anaemia and cerebral and spinal tumours. Coagulation disorders or ongoing anticoagulation treatment.

Dose and Administration: Local infiltration, max. 60 mL, using a 2.5 mg/mL (0.25%) solution. Peripheral nerve block, max. 60 mL, using a 2.5 mg/mL (0.25%) solution; max. 30 mL, using a 5 mg/mL (0.5%) solution. Epidural block Surgery, lumbar, max. 20 mL, using a 5 mg/mL (0.5%) solution, Surgery, caudal, max. 30 mL, using a 5 mg/mL (0.5%) solution; child (up to 10 years) using a 2.5 mg/mL (0.25%) solution, up to lower-thoracic (T10) 0.3–0.4 mL/kg, up to mid-thoracic (T6) 0.4–0.8 mL/kg, Labour, lumbar, max. 12 mL using a

2.5 mg/mL (0.25%) or 5 mg/mL (0.5%) solution; caudal max. 20 mL using a 2.5 mg/mL (0.25%) or 5 mg/mL (0.5%) solution. Sympathetic block, max. 50 mL, using a 2.5 mg/mL (0.25%) solution. Marcain Heavy: Dose Intrathecal anaesthesia for surgery, 2–4 mL (dose may need to be reduced in elderly and in late pregnancy).

ROPIVACAINE HYDROCHLORIDE:

Indications: Surgical anaesthesia Epidural blocks for surgery, including Caesarean section. Major nerve blocks. Field blocks. Acute pain management Continuous epidural infusion or intermittent bolus administration during postoperative or labour pain. Field blocks.

Contraindications: Hypersensitivity to ropivacaine or to other local anaesthetics of the amide type. General contraindications related to epidural anaesthesia, regardless of the local anaesthetic used, should be taken into account. Obstetric paracervical anaesthesia. Hypovolaemia.

Dose and Administration: Surgical anaesthesia: lumbar epidural, adult and child over 12 years, 15–20 mL of 10 mg/mL solution or 15–25 mL of 7.5 mg/mL solution (max. total dose 200 mg); caesarean section, 15–20 mL of 7.5 mg/mL solution in incremental doses (max. total dose 150 mg). thoracic epidural (to establish block for postoperative pain), adult and child over 12 years, 5–15 mL of 7.5 mg/mL solution. major nerve block (brachial plexus block), adult and child over 12 years, 30–40 mL of 7.5 mg/mL solution. field block, adult and child over 12 years, 1–30 mL of 7.5 mg/mL solution.

MEPIVACAINE HYDROCHLORIDE:

Indications: For the production of local anaesthesia for conservative and surgical interventions in the oral region (especially for dental work).

Contraindications: in patients with a known hypersensitivity to the amide type of local anaesthetic.

Dose and Administration: The dose varies and depends on the area to be anaesthetized, vascularity of the tissues, number of neuronal segments to be blocked, individual tolerances and the technique of anaesthesia. The lowest dose needed to provide effective anaesthesia should be administered. The average dose of one dental cartridge will usually suffice. This dose may be doubled if necessary to effect anaesthesia. The maximum adult dose should not exceed 400 mg mepivacaine hydrochloride, (approximately 7 mg/kg) at any one time and the total dose should not exceed 1 g in any twenty-four hour period.