Action and Spectrum

Actions and Spectrum:
Lidocaine works by blocking the conduction of nerve impulses by inhibiting the movement of sodium ions through voltage-gated sodium channels in neurons. This results in a decrease in the neuronal membrane’s permeability to sodium ions, which leads to the inhibition of depolarization and the blockade of conduction.

Chlorhexidine also binds to negatively charged cell walls and extra microbial complexes. At low concentrations, this causes an alteration of the bacterial cell’s osmotic equilibrium and leads to the leakage of potassium and phosphorous, resulting in a bacteriostatic effect. At high concentrations, the cytoplasmic contents of the bacterial cell residue and the cell dies. This is the mechanism by which chlorhexidine exhibits its bactericidal activity.

Drug Interaction

Adverse Reaction

Frequency defined:  

<1% 

Anaphylaxis 

Local discomfort 

Hypersensitivity reactions 

Black Box Warning

Contraindication / Caution

Contraindication / Caution:

Lidocaine is a local anesthetic that is used to numb a specific area of the body. It is generally considered safe when used as directed, but there are some precautions and contraindications to be aware of:

Allergic reaction: Some people may be allergic to lidocaine or other ingredients in the medication. If you have a known allergy to lidocaine or have experienced an allergic reaction, you should not use it.
Heart conditions: Lidocaine can cause changes in heart rhythm in some people, especially those with certain heart conditions. If you have a history of heart problems, you should talk to your doctor before using lidocaine.
Liver or kidney disease: Lidocaine is metabolized and eliminated by the liver and kidneys. If you have liver or kidney disease, you may be more sensitive to the effects of lidocaine, and your doctor may need to adjust the dose or use a different medication.
Children: Lidocaine should be used cautiously, as children may be more sensitive to its effects.

Chlorhexidine is an antimicrobial agent used to kill bacteria and other microorganisms. It is generally considered safe when used as directed, but there are some precautions and contraindications to be aware of:

Allergic reaction: Some people may be allergic to chlorhexidine or other ingredients in the medication. If you have a known allergy to chlorhexidine or have experienced an allergic reaction, you should not use it.
Children: Chlorhexidine should be used cautiously, as children may be more sensitive to its effects.
Pregnancy: There is limited information on the use of chlorhexidine during pregnancy, so it should be used with caution in pregnant women.
Nursing mothers: It is not known if chlorhexidine passes into breast milk. You should talk to your doctor before using chlorhexidine if you are nursing.

Pregnancy / Lactation

Pregnancy consideration: Insufficient data available 

Lactation: Excretion of the drug in human breast milk is known 

Pregnancy category: 

Category A: well-controlled and Satisfactory studies show no risk to the fetus in the first or later trimester.   

Category B: there was no evidence of risk to the fetus in animal studies, and there were not enough studies on pregnant women. 

Category C: there was evidence of risk of adverse effects in animal reproduction studies, and no adequate evidence in human studies must take care of potential risks in pregnant women.    

Category D: adequate data available with sufficient evidence of human fetal risk from various platforms, but despite the potential risk, and used only in emergency cases for potential benefits.    

Category X: Drugs listed in this category outweigh the risks over benefits. Hence these categories of drugs need to be avoided by pregnant women.    

Category N: There is no data available for the drug under this category 

Pharmacology

Pharmacodynamics 

The pharmacodynamics of lidocaine involves its effects on the body’s nervous system. Lidocaine works by inhibiting the conduction of nerve impulses along the axons of neurons. It does this by blocking the movement of sodium ions through voltage-gated sodium channels, proteins found in the cell membranes of neurons. When these channels are blocked, the nerve impulse cannot be transmitted, and the area of the body supplied by the affected neuron will become numb. 

The pharmacodynamics of chlorhexidine involve its antimicrobial activity. Chlorhexidine is an antimicrobial agent that kills or inhibits the growth of microorganisms. It does this by binding to the microorganism’s cell wall, disrupting its structural integrity and causing it to die. Chlorhexidine is active against many microorganisms, including bacteria, fungi, and viruses. It is particularly effective against gram-positive bacteria, which are a type of bacteria that are characterized by their ability to retain a crystal violet stain when exposed to certain dyes 

Pharmacokinetics 

Absorption 

The onset of action of lidocaine following systemic administration as a single IV bolus dose is 45 to 90 seconds. The duration of action is 10 to 20 minutes following a single IV bolus dose.  

Distribution 

Lidocaine is distributed throughout the body, with a volume of distribution of 0.8 to 2.8 L/kg. The protein binding of lidocaine depends on the drug concentration, and the fraction bound decreases with increasing concentration. At 1 to 4 mcg/mL concentrations, 60% to 80% of lidocaine is bound to alpha1 acid glycoprotein.  

Metabolism 

Lidocaine is metabolized in the liver by the enzymes CYP1A2 and CYP3A4; the active metabolites monoethylglycinexylidide (MEGX) and glycinexylidide (GX) can accumulate and may cause CNS toxicity.  

Elimination 

The elimination half-life of lidocaine is biphasic, with an initial half-life of approximately 8 minutes following a single IV bolus, a terminal half-life of 3.2 hours in infants, and 1.5 to 2 hours in adults. Lidocaine is excreted in the urine, with less than 10% excreted as an unchanged drug and about 90% excreted as metabolites. 

When applied topically, chlorhexidine is absorbed into the skin and mucous membranes. It is then metabolized by the liver and excreted in the urine. The pharmacokinetics of chlorhexidine are well understood, and it has a low potential for drug interactions when used topically. 

Adminstartion

Administration

To administer the gel, small portions should be slowly instilled into the urethra. The procedure should be performed 5-10 minutes later for less invasive procedures or 10-12 minutes later for more invasive procedures. In males, the entire urethra and external sphincter should be covered with the gel and the glans compressed until a local anesthetic effect is achieved. In females, some gel should be placed on the orifice and covered with a cotton swab. Discarding any unused gel portion and not administering it parenterally is essential. It is also important to avoid contact with the eyes. 

Patient Information Leaflet

Patient information leaflet 

Generic Name: lidocaine/ chlorhexidine 

Why do we use lidocaine/ chlorhexidine? 

chlorhexidine and lidocaine gel is a combination product that contains both a local anesthetic (lidocaine) and an antiseptic (chlorhexidine). This combination provides a dual action to address pain relief and infection prevention in certain medical procedures.

lidocaine is a local anesthetic that is used to numb a specific area of the body. It is commonly used in dental procedures, to numb the skin before injecting medication, and to reduce pain during specific medical procedures. 

chlorhexidine is an antimicrobial agent used to clean the skin and disinfect medical equipment. It is also found in mouthwashes and toothpaste to help kill bacteria in the mouth.