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Lignocaine &
Chlorhexidine Gel
Product Name
Lignocaine 2% gel with Chlorhexidine 0.05%
Name of drug
Lignocaine USP and Chlorhexidine gluconate (as Chlorhexidine Gluconate Solution BP).
Description
Lignocaine belongs to the amide group. Its chemical name is 2-diethylaminoaceto-2', 6' xylidide. It is a white to almost white crystalline powder that is practically insoluble in water, very soluble in dichloromethane and in ethanol and freely soluble in ether. The structural formula is represented below:
Molecular Formula: C14H22N2O
Molecular Weight: 234.3
CAS Number: 137-58-6
Chlorhexidine gluconate is 1,1'-hexamethylenebis[5-(4-chlorophenyl) biguanide] di(D-digluconate). It is an almost colourless to pale yellow liquid. It is miscible with water, soluble in alcohol and acetone. The structural formula is represented below:
Molecular Formula: C22H30CI2N10,
2C6H12O7
Molecular Weight:
898
CAS Number:
18472-51-0
Lignocaine and chlorhexidine gel is a sterile, colourless, water-soluble gel containing Lignocaine 20mg/mL, Chlorhexidine 500µg/mL, Polypropylene Glycol BP, Hydroxyethyl
Cellulose NF, Glacial Acetic Acid BP, Sodium Hydroxide BP (for pH
adjustment) and Water for Injections BP.
Pharmacology
Lignocaine is a local anaesthetic of the amide type. It produces a reversible loss of sensation by preventing or diminishing the conduction of sensory nerve impulses near the site of application. It is readily absorbed from mucous membranes and damaged skin producing rapid, local anaesthesia in these areas. Absorption from intact skin is poor. The rate of absorption and amount of dose absorbed is dependent upon concentration, the total dose administered, the specific site of application and the duration of exposure.
Lignocaine is metabolised rapidly by the liver, with both metabolites and unchanged drug excreted by the kidney. Approximately 90% of lignocaine is excreted as metabolites and less than 10% is excreted as unchanged drug. Excessive blood levels of lignocaine may cause changes in cardiac output, total peripheral resistance and mean arterial pressure. These changes may be attributed to a direct depressant effect of the anaesthetic agent on various components of the cardiovascular system. The pharmacological/ toxicological actions of the metabolites are similar to, but less potent than those of lignocaine.
The plasma binding of lignocaine is dependent on drug concentration, and the fraction bound decreases with increasing concentration. At concentrations of 1 to 4 microgram free base/mL, 60 to 80% of lignocaine is protein bound. Binding is also dependent on the plasma concentrations of the alpha1 -acid glycoprotein. Lignocaine crosses the blood brain and placental barriers.
Studies of lignocaine metabolism following IV bolus injection have shown that the elimination half-life is usually 1.5 to 2 hours. The halflife may be doubled in patients with hepatic dysfunction. Renal dysfunction does not affect lignocaine kinetics, but may increase the accumulation of metabolites.
Acidosis and the use of CNS stimulants and depressants affect the CNS levels of lignocaine required to produce systemic effects. Adverse reactions become increasingly apparent with venous plasma levels above 6.0 microgram free base/mL.
Chlorhexidine is an antiseptic effective against a wide range of Grampositive and Gram-negative organisms, some viruses and some fungi. It is ineffective against bacterial spores at room temperature and acid-fast bacteria are inhibited but not killed. It is more active against Gram-positive than Gram-negative bacteria and some species of Pseudomonas and Proteus are relatively less susceptible.
Chlorhexidine is most active at a neutral or slightly acid pH and its activity is reduced in the presence of blood or other organic matter.
Indications
• local anaesthesia and lubrication during catheterisation, exploration
by sound and other endourethral operations and examinations.
• cystoscopy and symptomatic treatment of painful cystitis and
urethritis.
Contraindications
• known hypersensitivity to either of the active ingredients.
• known hypersensitivity to any of the excipients.
• hypersensitivity to other amide type local anaesthetics.
Precautions
Not for injection.
• Excessive dosage, or short intervals between doses, can result in
high serum levels of lignocaine or its metabolites and serious
adverse effects, therefore the recommended dosage and
administration guidelines should be strictly followed. Where
possible the lowest dose that results in effective anaesthesia should
be used to avoid high plasma levels and serious adverse effects.
• As tolerance to elevated blood levels varies with the status of the
patient, use with caution in patients with severely traumatised
mucosa and/or sepsis in the region of proposed application.
Care is also required with elderly, acutely ill patients and children
who should be given reduced doses relative to their age and
physical status.
• If the dose or site of administration is likely to result in high blood
levels, lignocaine, in common with other local anaesthetics, should
be used with caution in patients with epilepsy, impaired cardiac
conduction, bradycardia, impaired hepatic function, severe shock
and patients with severe renal dysfunction.
Driving, operating machinery and other activities requiring mental alertness: Depending on the dose administered, local anaesthetics may have a very mild effect on mental function and may temporarily impair locomotion and coordination.
Use in pregnancy: Category A. Lignocaine crosses the placental barrier and may be taken up by fetal tissues. When used for surface anaesthesia, lignocaine blood levels following normal administration are low thus minimal drug is available for placental transfer. No specific disturbances to the reproductive process have so far been reported,
Use in lactation: Lignocaine enters the breast milk, but in such small quantities at therapeutic dose levels that there is generally no risk when breastfeeding.
Although it is not known whether chlorhexidine is excreted in breast milk, problems in humans have not been documented.
Interactions with other drugs:
Cimetidine has been shown to reduce clearance of IV administered lignocaine. Caution should be taken if administered concurrently with lignocaine.
Antiarrhythmic drugs: Lignocaine should be used with caution in patients receiving antiarrhythmic drugs such as mexiletine, since the toxic effects are additive.
Antiepileptic drugs: Phenytoin and other antiepileptic drugs such as phenobarbitone, primidone and carbamazepine appear to enhance the metabolism of lignocaine but the significance of this effect is not known. Phenytoin and lignocaine have additive cardiac depressant effects.
Incompatibilities: Chlorhexidine is incompatible with soaps and other anionic materials.
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