Cephalexin Tablets

[Pharmacology and Toxicology] This product is a semi-synthetic cephalosporin broad-spectrum antibiotic. The antibacterial spectrum is similar to that of cephalothin, but the antibacterial activity is poorer than that of cephalothin. This product is stable to the penicillinase produced by Staphylococcus aureus, so it has a good antibacterial effect on penicillin-resistant Staphylococcus aureus. Except for Enterococcus and methicillin-resistant Staphylococcus, most Gram-positive cocci are sensitive to this product. This product has a good antibacterial effect on Neisseria, and has antibacterial effects on some Escherichia coli, Proteus mirabilis, Klebsiella pneumoniae, and Salmonella; it has a poor effect on Haemophilus influenzae; other Enterobacteriaceae, Acinetobacter, Pseudomonas aeruginosa, and Bacteroides fragilis are resistant to this product. The mechanism of action of this product is to inhibit the synthesis of bacterial cell walls. [Pharmacokinetics] Take 500 mg of this product orally on an empty stomach, and the peak blood concentration (Cmax) is about 18 mg/L in about 1 hour. The absorption of this product can be increased in patients with celiac disease and small intestinal diverticulum in young children; it is delayed and reduced in patients with Crohn's disease and pulmonary cystic fibrosis; the blood concentration of the elderly is more persistent than that of young people; newborns take 15 mg/kg of this product orally 2 hours after feeding, and the average blood peak concentration is reached after 6 hours, which is about 4.5 mg/L. The average concentration in sputum after taking 500 mg of this product orally every 6 hours is 0.32 mg/L, and the concentration in purulent sputum is higher. The concentration in pus and osteomyelitis fistula is basically equal to the blood concentration, and the concentration in joint cavity exudate is about half of the blood concentration. After pregnant women take 500 mg of this product orally, the effective concentration can be obtained in amniotic fluid and umbilical cord blood; after lactating women take 500 mg of this product orally, the concentration in breast milk is about 5 mg/L. The concentration in bile is 1 to 4 times the blood concentration. This product is difficult to penetrate the blood-cerebrospinal fluid barrier. The distribution volume is about 0.26L/kg. The protein binding rate is 10% to 15%. The blood elimination half-life (t1/2?) is 0.6 to 1.0 hours. In case of renal failure, t1/2? can be extended to 5 to 30 hours. In newborns, t1/2? is about 6.3 hours. This product is not metabolized in the body and is excreted in its original form through glomerular filtration and tubular secretion. The amount of excretion in urine in 24 hours is 80% of the dose. After taking 500 mg of this product orally, the peak concentration in urine can reach 2200 mg/L. About 5% is excreted by bile, and the content in feces is very low. This product can be removed by hemodialysis and peritoneal dialysis.

The main ingredient of this product is cephalexin, and its chemical name is (6R,7R)-3-methyl-7-[(R)-2-amino-2-phenylacetylamino]-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid monohydrate.

This product is a sugar-coated tablet or a film-coated tablet, which appears white or creamy yellow after removing the coating.

This product is suitable for mild and moderate acute tonsillitis, pharyngitis, otitis media, sinusitis, bronchitis, pneumonia and other respiratory tract infections, urinary tract infections and skin and soft tissue infections caused by sensitive bacteria.

Put this product into warm water and drink it after it dissolves. Oral administration for adults: 0.25-0.5g once every 6 hours. The highest dose is 4g per day. For patients with simple cystitis, skin and soft tissue infections and streptococcal pharyngitis, take 500mg once every 12 hours. For children, take 25-50mg/kg per day according to body weight, once every 6 hours. For patients with skin and soft tissue infections and streptococcal pharyngitis, take 12.5-50mg/kg according to body weight, once every 12 hours.

1. Common gastrointestinal reactions: soft stools, diarrhea, stomach discomfort, loss of appetite, nausea, vomiting, heating, etc. 2. Rare allergic reactions such as rash and drug fever and nervous system reactions such as dizziness, diplopia, tinnitus, convulsions, etc. 3. When some patients with endocarditis take this product at high doses (20-40g per day, with probenecid added), hematuria, eosinophilia and increased serum creatinine may occur, but the above reactions will disappear quickly after drug withdrawal. 4. Occasionally, serum aminotransferase increases, antiglobulin (Coombs) test is positive, granulocytopenia and pseudomembranous colitis are seen; hemolytic anemia is rare.

It is contraindicated in patients who are allergic to cephalosporins or have a history of anaphylactic shock or immediate reaction to penicillin.

Precautions for children: Precautions for pregnancy and lactation: This product crosses the placenta, so pregnant women should use it with caution; this product can also be excreted through breast milk. Although there are no reports of problems with the use of cephalosporins in lactating women, it is still necessary to weigh the pros and cons before using it. Precautions for the elderly:

1. Furosemide, ethacrynic acid, bumetanide and other strong diuretics, carmustine, streptozocin and other antineoplastic drugs and aminoglycoside antibiotics and other nephrotoxic drugs combined with this product may increase nephrotoxicity. 2. Clavulanic acid can enhance the antibacterial activity of this product against certain Gram-negative bacteria that are resistant to this product due to the production of β-lactamase. 3. Probenecid can delay the excretion of this product through the kidney, extending the blood elimination half-life (t1/2?) of this product to 107 minutes; however, there are also reports that probenecid can increase the excretion of this product in bile. 4. When this product is used in combination with cholestyramine (cholestyramine), the average blood peak concentration of this product can be reduced.

Keep away from light, seal tightly and store in a cool dark place.

0.25g

24 months