What Is Methicillin?

Methicillin , methicillin sodium, is a penicillin-resistant penicillin. Its antibacterial effect is similar to that of penicillin, but it is not hydrolyzed by penicillinase, and it has a good effect on penicillinase-producing Staphylococcus aureus. The product has antibacterial activity against Gram-positive bacteria and Neisseria, but the antibacterial effect of penicillin-sensitive staphylococci, various streptococci and meningococci is less than penicillin.

Methicillin

Methicillin , ie

Name: Methicillin;

Methicillin is resistant

See

Based on methicillin. For injection

Child, male, four months, because

[Drug Name] Methicillin

Category Name

Primary classification: Antibiotic secondary classification: Penicillin tertiary classification:

[English name of drug]

Meticillin

[Drug alias]

Dimethoxypenicillin, dimethicillin, methicillin, neopenicillin , methicillin, Azapen, Celbenin, Dimocillin

[Drug form]

Injection (powder): 1g, 4g, 6g, 10g.

[Pharmacological action]

This product has a good effect on penicillin-producing Staphylococcus aureus, and its MIC is 2 g / ml. The antibacterial activity of Penicillin-sensitive Staphylococcus, Group A hemolytic streptococcus, Streptococcus grass green and Neisseria meningitidis was only 1/10 to 1/50 of penicillin. Except for Haemophilus influenza (sensitivity is 2 g / ml), Gram-negative bacilli are resistant to this product.

Pharmacokinetics

This product is not absorbed orally and must be administered by injection. After intramuscular injection of 1 g, tmax was 30 to 60 min, and Cmax was 12 to 17 g / ml. Intravenous injection of 1g, serum concentration in the range of 20 ~ 40g / ml. The serum protein binding rate was 35% to 40%. Like other penicillins, most of the drugs enter the extracellular fluid. Methicillin is rapidly excreted from the kidneys in the form secreted by the glomeruli. About 80% of the drug is excreted from the urine in its original form, and less than 10% of the drug is metabolized. The elimination half-life of patients with normal renal function is about 30 minutes, and the half-life of patients with impaired renal function is prolonged. Care should be taken to adjust the dosage when using it.

Indications

It is mainly used to treat sepsis, endocarditis, pneumonia, meningitis, brain abscess, pericarditis, urinary tract infection, skin and soft tissue infection, osteomyelitis, pseudomembranous enteritis caused by Staphylococcus aureus.

Contraindications

Those with a history of allergies to penicillin are contraindicated.

Precautions

A penicillin skin allergy test is required before use.

Adverse reactions

Intramuscular injection of this product is more painful, leukopenia is more common, and it returns to normal after stopping the drug. Interstitial nephritis can occur with large doses of intravenous administration, manifested as hematuria and proteinuria, which can be accompanied by fever, rash, increased eosinophils, and even renal function. The vast majority of patients recovered completely after discontinuation.

Dosage

Methicillin can be administered in the form of intramuscular injection (500mg / ml), direct intravenous injection (20mg / ml) and intravenous drip: 6-12g per day for adults, 100-250mg / kg per day for children, divided into 3 to 4 times , Soluble in 0.9% sodium chloride injection for 10 to 20ml by intravenous injection for 5min, or in 0.5% lidocaine injection for intramuscular injection.

[Medicine corresponding effects]

Probenecid can inhibit renal tubular secretion, so it can prolong the maintenance time of penicillin blood concentration, which has a synergistic effect on this product.

Expert Reviews

This product is the first penicillin-resistant penicillin to be used clinically. Due to its low antibacterial activity, unsatisfactory curative effect, and many adverse reactions, it has been largely discontinued, and it is rarely produced and applied abroad.