Quinolones were first discovered in the 1960s. The slow development in the 1970s, the development of fewer species, side effects. Since the synthesis of quinolone drugs in 1980, the development has been extremely rapid. In 1995, among the anti-infective drugs ranked second in the world's prescription drug market, quinolones accounted for the first place. Has now developed to the fourth generation of products.
Quinolones are DNA gyrase inhibitors, which act on bacterial DNA gyrase and interfere with the unwinding of the DNA supercoiled structure, thus hindering DNA replication and exhibiting bactericidal action. Therefore, it is a slow-acting fungicide in terms of classification.
The common characteristics of this class of drugs are: strong antibacterial effect, broad spectrum of antibacterial activity, mainly against gram-negative bacteria, and also have considerable effect on gram-positive bacteria. It is widely distributed in the body and can enter bones, joints, and prostate tissues that most drugs cannot enter. What is even more gratifying is that quinolones not only rarely produce drug resistance themselves, but also have no cross-resistance with other kinds of antibiotics, which is beneficial to the combination of other antibiotics.
Classification of quinolones and their characteristics
Quinolones are divided into four generations according to the invention and their different antibacterial properties.
The first generation: narrow antibacterial spectrum, effective only for a few bacteria such as Escherichia coli, Shigella and Proteus. On behalf of drugs: nalidixic acid, pyrrolic acid, due to poor efficacy, side effects, has now completely eliminated.
The second generation: Launched in 1980, the antibacterial spectrum has been expanded. Due to the high concentration of urine and bile after absorption and metabolism, urinary tract infections and biliary tract infections and bacteria are involved in acute and chronic pyelonephritis, cystitis, and prostatitis. Blemishes and enteritis are more effective. Representative varieties are pipemidic acid (PPA), oxalic acid and methoxy oxolinic acid. Due to the fact that the side effects are still relatively large, they have been eliminated except PPA.
The third generation: came out in the 80s of last century, the antibacterial spectrum was expanded, the antibacterial effect was strong, and the lower concentration showed antibacterial activity. It can fight gram-positive bacteria such as resistant staphylococci, and has better efficacy against gram-negative bacteria. This class of drug molecules contain fluorine atoms, it is called fluoroquinolones. These drugs are used to treat severe infections and recurrent chronic infections, especially urinary tract infections. The main varieties are: Norfloxacin, Ofloxacin, Ciprofloxacin, Enoxacin, Mefloxacin, Enrofloxacin, Lomefloxacin, Fleroxacin, Gatifloxacin, Sparfloxacin, etc. Wait.
The fourth generation: In recent years, foreign developed fourth-generation quinolone antibiotics, such as moxifloxacin, clinoxacin and gemifloxacin. The main features are: a novel 8-methoxyfluoroquinolone in the structure, the introduction of methoxyl contributes to the strengthening of anti-anaerobic activity, and the nitrogen bicyclic structure at the C-7 position enhances the activity against Gram-positive bacteria and maintains The original anti-gram-negative bacteria activity, side effects are smaller, but the price is more expensive. The greatest contribution of moxifloxacin to antibacterial agents is that it increases the activity of anaerobic bacteria based on the activity of the aerobic G+ cocci. Gemifloxacin enhances the activity of G+ cocci and has a good effect on MRSA, Pseudomonas aeruginosa, Chlamydia pneumoniae, Mycoplasma, and Legionella pneumonia.
Quinolone in vivo antibacterial process
Oral absorption is fast, basically not affected by food, reaching the peak blood concentration within 1 to 2 hours. The body is widely distributed, and the concentrations in liver, kidney, pancreas, lymph nodes, parotid glands, bronchial mucosa, biliary tract, and urine are all higher than those in blood. Most of the quinolone is excreted in the urine and the patient is not tolerant.
Quinolone's mechanism of action: It acts as a bactericidal agent for inhibiting the synthesis and replication of bacterial DNA, and it has a strong penetration and destruction ability against the bacterial cell wall. Thus, it has a powerful bactericidal action. Its antibacterial effect (PAE) is strong and long lasting. Quinolone adverse reactions
In general, the adverse effects of this class of drugs are relatively minor in all major categories of antibiotics. Although the incidence of adverse reactions is low, it should not be ignored. Adverse reactions of this class of drugs:
The incidence of digestive system is very low. Nausea and vomiting, loss of appetite, abdominal pain, diarrhea, etc., disappeared after discontinuation; long-term application can cause bacterial diarrhea.
The incidence of central nervous reaction is only 1%. It has an inhibitory effect on the central nervous system, manifested as headache, dizziness, insomnia, hallucinations, memory loss, very few manifestations of numbness in hands and feet, finger trembling, etc., have history of mental illness and epilepsy were hanged.
This type of drug is easily concentrated and deposited in the bone marrow, directly poisoning the development of chondrocytes and affecting the skeletal development of children and fetuses. Therefore, pregnant women and children under the age of 12 should be banned. Breastfeeding should be stopped during lactation.
Allergic reactions (allergic reactions) occur in individuals with specific physiques. The main manifestations are rash, urticaria, dermatitis, and exfoliative dermatitis, with ciprofloxacin and norfloxacin being more. Most of these reactions are heavier and generally occur several days to several weeks after taking the drug. Asthma, dyspnea, laryngeal edema, angioedema, allergic vasculitis, and anaphylactic shock are all serious allergic reactions. Therefore, ultraviolet and sunlight should be avoided during medication.
A few quinolone drugs (such as lomefloxacin) have a prominent feature, namely photosensitizing reactions. After taking the drug, it can happen even without direct sunlight, and it is even worse in the sun. Therefore, pharmacists should remind patients who use drugs to avoid sun exposure after taking the drug, and do not receive artificial ultraviolet radiation.
Most of the drugs in this class are excreted in the urine from their original form. Their urine concentration is 5 to 6 times higher than the blood concentration, causing damage to the kidney in varying degrees, mainly including hematuria and crystalline urine. Hematuria is due to the formation of crystallization of drugs in the urine, and no renal parenchymal damage, but renal insufficiency caution.
After taking quinacridone drugs, some patients may have crystalline urine, hematuria, and hyperuricemia, and may even develop allergic interstitial nephritis or oliguric renal failure.
High-dose or long-term use of such drugs is prone to liver damage. Increased aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase increased as drug-induced jaundice, yellowing of the sclera (eye white), skin, and mucous membranes.
Combined drug and drug interactions
1. It should not be used in combination with theophylline drugs. 2. Basic drugs, anticholinergic drugs, H2 receptor blockers (cimetidine, ranitidine, etc.) can reduce gastric acidity, thereby reducing the absorption of this class of drugs, it should avoid the same service. 3. Should not be taken at the same time as the alkalizing agent. 4. The antacids containing calcium, magnesium, and aluminum can reduce the absorption and utilization of this type of drug, lower the blood peak concentration, continue at the peak time, and reduce the AUC (area under the curve), so they should be avoided. 5. This type of drug interacts with GABA to produce a variety of psychiatric symptoms that are easily induced by epilepsy. Should not be combined with anticonvulsants, and non-steroidal anti-inflammatory drugs (such as ibuprofen, fenbufen, sulindac, etc.) combined, can cause central seizures. 6. This type of drug inhibits theophylline metabolism and increases the blood concentration of theophylline, resulting in theophylline poisoning, especially in the elderly.
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