What do you know about metabolism and excretion?

The metabolic and excretion of narcotic drugs is an extremely important part of anaesthesia, which affects not only the maintenance of anaesthesia but also the safety and rehabilitation of patients. After entering the body, the substance is eventually metabolized and excreted through a complex set of physiological processes. Understanding the process is essential for the rational selection of narcotic drugs, the adjustment of doses, the prediction of the time of the drug ‘ s effects and its elimination.

1. Metabolism of narcotic drugs. Metabolism of narcotic drugs occurs mainly in the liver and is converted to active or inactive metabolites through enzymes. This process can be divided into two main phases: the first phase: biotransformation, during which the drug molecules are transformed by oxidation, reduction, hydrolysis or combination. For example, fentanyl metabolizes in the liver through CYP3A4 enzymes, producing more active metabolites. The metabolites at this stage usually have different pharmacological activities and may be more easily metabolized or excreted. Phase 2: Combined metabolisms Metabolisms are combined in the liver with glucose algebraic acid, sulphate, cythacylla, etc., to form more water soluble compounds that can be excreted through urine or cholesterol. This process enhances the water solubility of the drug and contributes to its release.

Excretion of narcotic drugs is mainly through the kidney and liver, as well as through the respiratory system and skin. Kidney excretion, mostly through kidneys. Medicines and their metabolites are filtered into urine in the kidneys and then excreted through urine. Renal excretion capacity is affected by a number of factors, including the water solubility of the drug, acid alkalinity, kidney function, etc. Some drugs (e.g. benzodiazepines) may take longer to be completely eliminated and may require longer monitoring and observation periods. The liver is excreted, and the liver is involved not only in metabolism, but also in excretion. The liver is excreted of certain drugs or their metabolic products through choreography, especially those that are not easily excreted through kidneys. Courage excretion is another important way for drugs to be discharged from the body. Respiratory system and skin excretion Very few narcotic drugs may be excreted through the respiratory system or skin. For example, inhalation anaesthesia may be partially excreted through the lung, while some local anaesthesia may also be excreted through skin absorption.

3. Individual differences. There are significant differences in the metabolic and excretion capacity of different individuals for narcotic drugs, mainly determined by genetic, age, sex, state of disease, etc. For example, patients with liver diseases may affect the metabolic rate of the drug because of impaired liver function; the kidney function of older persons may decrease, leading to slower drug removal; and pregnant women may need additional consideration for metabolic drugs, which may affect the foetus.

4. Monitoring and adjustment of narcotic drugs By monitoring the concentrations of blood, urine or blood metabolites, it is possible to adjust drug doses in a timely manner to avoid overdoses or deficiencies and to ensure anaesthesia and patient safety.

The metabolic and excretion of narcotic drugs is a complex but critical process that directly affects the maintenance of anaesthesia and the safety of patients. Knowledge and control of the process are essential for anaesthetists to better select and adapt anaesthesia and to provide safer and more effective anaesthesia services for patients.