Availability
- Lignocaine HCL 2% (no preservative) (100mg/5ml)
- Lignocaine HCL 2% (preservative) (200mg/10ml)
Rationale
- One of the major disadvantages of IM injection of penicillins, such as benzathine penicillin G, is pain at the injection site.
- Farhadi et al. reported that the average pain intensity in patients receiving IM injection of benzathine penicillin was described as "severe" with a mean visual analog scale (VAS) score of 7.4/10
- Injection pain can be greatly reduced by administering drugs in combination with local anesthetics like lidocaine.
- Lidocaine is a sodium-channel-blocking drug and an extremely versatile local anesthetic agent which has remained a widely used agent due to its potency, rapid onset and intermediate duration of action
Stability
- A few studies have examined the influences of lidocaine as a diluent on pharmacokinetics of IM penicillins or cephalosporins in human and none showed any changes in pharmacokinetic parameters of these antibiotics when mixed with lidocaine
- Patel et al. investigated the effect of lidocaine 1% as a diluent on the pharmacokinetics and tolerance of IM ceftriaxone and showed that lidocaine neither changed parameters nor altered its bioavailability
- Amir et al. compared concentration and injection pain of benzathine penicillin G between two diluents, either sterile water or lidocaine hydrochloride 1%. They found that although lidocaine significantly reduced injection pain, it did not change penicillin concentration in body fluids
Toxicity
- Despite potential toxicity of lidocaine, its usual dose for IM penicillin injections is 10-60 mg (1-3 mL of lidocaine 1% or 2%) which is significantly less than the recommended maximum dose for local anesthetics without epinephrine (4.5 mg/kg)
Administration Recommendations
Vol of Lignocaine 2% | Diluent Solutions | Used to Reconstitute: | |
1. | 1.75 ml | 1.75 ml of NS, 1/2NS, D5, NSD5 | 1g Ceftriaxone powder |
2. | 0.25ml | WFI | 1.2 MU Benzathine Penicillin powder in at least 3ml of WFI 0.6 MU (2 ml) 2.4MU (5 ml) |
References:
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3464756/
- Product Leaflets
- https://www.health.govt.nz/.../nursing_guidance_-_administering_im_penicillin.pdf
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