Compatibility and Dosage of Gentamicin Combination
1. Gentamicin has the following characteristics
1) It is a bactericidal antibiotic.
2) It is a broad-spectrum aminoglycoside.
3) There is an obvious post-antibiotic effect (PAE) for Gram-negative bacteria and positive cocci, that is, it has a sustained antibacterial effect below the inhibitory concentration and completely eliminates the drug, or the drug concentration is below the minimum inhibitory concentration (MIC ), the growth of bacteria continues to be inhibited for a certain period of time.
4) It is a concentration-dependent antibacterial drug.
Recent studies have shown that the antibacterial activity of gentamicin depends on the effective concentration of cell membrane antibiotics. Under the condition that the daily dose remains unchanged, a single dose can achieve a greater peak plasma concentration of multiple doses a day, so that the peak The ratio of the concentration to the minimum inhibitory concentration is increased, thereby significantly improving the antibacterial activity and clinical efficacy.
In addition, the post-antibiotic effect (PAE) of gentamicin on pathogenic bacteria is also concentration-dependent. A single daily dose can reduce the incidence of adaptive drug resistance and ear and nephrotoxicity, and can also reduce the incidence of pig grabbing. Stress response caused by medication and injection.
5) This product is rarely absorbed by oral administration and has a high concentration in the intestinal tract. It can be used as a medicine for intestinal infections and treat yellow and white diarrhea and enteritis of piglets.
6) This product is quickly and completely absorbed by injection, and the peak blood concentration will be produced within 0.5-1 hours of intramuscular injection, and the bioavailability can reach 90%. When the dose is increased, the blood concentration can be increased, and the duration can be extended appropriately.
7) This product is an alkaline compound, easily soluble in water, relatively stable, and has the strongest antibacterial activity in an alkaline environment.
8) If the dosage of gentamicin is too large or the treatment time is too long, there will be certain toxic and side effects.
9) Bacteria are also prone to drug resistance to this product, but drug-resistant strains are far less common than streptomycin and kanamycin. If the dosage is sufficient or combined with other antibiotics, and avoid topical medication, it can reduce or prevent the occurrence. Once it happens, stop the drug immediately and the bacteria can restore sensitivity. There is incomplete cross-resistance among different varieties of aminoglycosides.
2. Drug interactions
1) The combination of gentamicin and β-lactam antibiotics (such as penicillins or cephalosporins) usually has a synergistic effect on a variety of gram-negative bacteria, including Pseudomonas aeruginosa. It also has a synergistic effect on Gram-positive bacteria. For example, gentamicin is combined with penicillin for streptococcus, with enzyme-resistant semi-synthetic penicillin for Staphylococcus aureus, combined with cephalosporin for pneumoniae, and penicillin G or ampicillin for Listeria and Carbenicillin is used in combination with Pseudomonas aeruginosa. This is because β-lactam drugs cause bacterial cell wall damage, which can increase the uptake of gentamicin by the bacterial cell membrane, because the cell wall damage makes it easy for the drug to approach the cell membrane.
2) Combined with trimethoprim-sulfa, it also has a synergistic effect on Escherichia coli and Klebsiella pneumoniae.
3) In the treatment of severe systemic infections, this product can be used in combination with dexamethasone, florfenicol, etc., with a higher cure rate.
4) This product has an enhanced antibacterial effect in an alkaline environment. Combining with alkaline drugs (such as sodium bicarbonate, aminophylline, etc.) can enhance antibacterial activity, but the toxicity is correspondingly enhanced. When the PH value exceeds 8.4, the antibacterial effect decreases instead.
5) It is forbidden to mix with vitamin C, so as not to reduce the efficacy.
Three, indications
Gentamicin has a good effect on the treatment of severe infections caused by sensitive bacteria. Clinically, it is mainly used to control and treat local and systemic infections caused by drug-resistant Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Proteus, Pasteurella, Salmonella and other aerobic gram-negative bacteria. Such as sepsis, urogenital infections, respiratory infections (pneumonia, bronchopneumonia), gastrointestinal infections (including peritonitis), mastitis, osteoarthritis and skin and soft tissue infections.
Four, usage and dosage
The potency of this product is calculated by weight, and 1 gram is equal to 1 million units.
1) Take it orally for a day, 10-15mg per kilogram of body weight, 2-3 times a day, for 2-3 days.
2) Intramuscular injection: One dose, 2-4 mg per kilogram of body weight, twice a day, for 2-3 days.
The above is the recommended dosage in the official "Guidelines for the Use of Veterinary Drugs". The following is a proven prescription for the treatment of piglet diarrhea, which is summarized by the author after ten years of repeated trials. The dose is larger than the official recommended dose, and the clinical effect is good. Those who are interested may wish to try: gentamicin powder 5.0 g, methoxy 1.0 g of benzylamine, 20 scopolamine tablets (5 mg/tablet), 13.75 g of oral rehydration salt, 500 ml of cold boiled water, once orally, 1 ml per kilogram of body weight, twice a day, for 2-3 days. If you want to reduce the stress caused by catching pigs, you can only administer it once a day, and you can administer 2.0 ml per kilogram of body weight. If the piglet weighs more than 10kg, it is inconvenient to administer the medicine. Gentamicin injection can be injected intramuscularly. The amount of intramuscular injection is 6-8mg per kilogram of body weight, that is, 0.15-0.2ml/kg body weight of 4% gentamicin injection, twice a day for 2-3 days. If it is injected intramuscularly once a day, the dose can be doubled. For severe dehydration cases, gentamicin injection can also be added to 20-40ml of 5% dextrose saline for intraperitoneal injection. Regardless of gavage, intramuscular injection or intraperitoneal injection in severe cases, the dosage can be appropriately increased as appropriate.
Five, use matters needing attention
1) Although gentamicin can be used in combination with penicillin or cephalosporins, it cannot be diluted with gentamicin injection, and cannot be mixed in the same syringe or vial for injection, otherwise it will reduce the efficacy of gentamicin , Penicillin and gentamicin can be injected intramuscularly or instilled respectively.
2) When the newborn piglets are not taking colostrum, it is best not to take gentamicin to prevent yellow scour of the piglets. The author once believed credulously some articles published in newspapers, saying that administering 60,000 units of gentamicin to piglets before taking colostrum can prevent yellow diarrhea of piglets. I tried this way, and as a result, 6 of 10 piglets died one after another. The cause of death was a severe ulcer at the bottom of the stomach. The author recommends that piglets without colostrum and empty stomach should not take gentamicin to prevent yellow diarrhea, so as to avoid gastric ulcers and cause undue losses.
3) This product cannot be used in combination with similar aminoglycoside drugs such as streptomycin, kanamycin, amikacin, neomycin, etc., to prevent enhanced toxicity.
4) This product cannot be injected intravenously, because it has respiratory depression.