Kidneys are important vital organs in the human body, with multiple physiological functions:
① Excretory function: The kidneys eliminate metabolic waste products, drugs, and toxins through the generation and excretion of urine.
② Regulatory function: The kidneys regulate body fluid osmotic pressure, fluid volume, and electrolyte concentrations, maintaining acid-base balance and blood pressure.
③ Endocrine function: The kidneys secrete renin, which participates in the regulation of arterial blood pressure; they also synthesize erythropoietin to regulate the production of red blood cells in the bone marrow, improving anemia; the kidneys' 1α-hydroxylase converts 25-OH-D3 into the active form 1,25-(OH)2-D3, thus regulating calcium and phosphate metabolism; the kidneys also produce prostaglandins and kinins, which participate in the regulation of local or systemic vascular activity. The kidneys also have the function of inactivating parathyroid hormone and gastrin.
Basic principles and precautions
When renal function is impaired, drug metabolism and excretion are affected. For the same drug and dose, it may be safe for patients with normal renal function, but it may lead to accumulation and worsen renal damage in patients with renal insufficiency. Due to the limited availability of drugs (variety and efficacy) and the infinite diversity of diseases (types and severity of diseases), when treating patients with renal insufficiency, it is not enough to simply judge the rationality of drug use based on whether the disease is cured. The potential harm of the drugs used should also be considered, and special attention should be paid to the cautious selection of drug varieties and doses. Basic principles and precautions for drug use in patients with renal insufficiency.
(1) Clarify the diagnosis of the disease and treatment goals
In treatment, the diagnosis of the disease should be clarified first, and an accurate analysis of the pathological and physiological processes and the current situation of the disease should be made. Reasonable drug selection should be based on both indications and contraindications. Then, the treatment goals should be clearly defined, whether it is to treat the symptoms or the root cause. After a period of treatment, observe whether the goals have been achieved to determine the rationality of drug use and whether adjustments are needed, in order to avoid blind medication.
(2) Avoid nephrotoxic drugs
The kidneys are the main route for drug excretion, and caution should be exercised when administering drugs to patients with renal insufficiency. Drugs that may cause renal damage should be avoided as much as possible. If necessary, drugs with less renal damage should be used as alternatives, and short-term or alternating use is recommended to avoid excessive use.
(3) Pay attention to drug interactions to avoid causing new kidney damage
When taking multiple drugs at the same time, attention should be paid to drug interactions and the formation of new renal damage due to the interaction of drug metabolites. In many cases, it is difficult to determine the renal damage caused by Chinese herbal medicines, especially compound drugs. In some cases, it may not be entirely accurate to attribute renal damage to a single drug. Therefore, as a practicing pharmacist, it is important to be familiar with which drugs can cause renal damage, their main clinical manifestations, and pathological changes, which are important for preventing and detecting drug-induced renal damage.
(4) Adhere to the principle of using fewer drugs but more effectively
In patients with renal insufficiency, various complications or other diseases often occur, resulting in various clinical symptoms and manifestations. In treatment, it is important to eliminate pathogenic factors and support vital energy. This is especially important in the treatment of renal failure. Comprehensive analysis of the patient's disease status is necessary to select a few effective drugs for treatment.
(5) Regularly check and adjust the treatment plan in a timely manner
When dealing with patients with renal insufficiency, it is important to be responsible throughout the treatment process. Close observation of disease progression, changes in renal function, and the appearance of adverse drug reactions is necessary for timely adjustment of dosage or replacement of treatment drugs. In general, reducing the drug dosage or extending the dosing interval according to the degree of renal impairment can avoid further damage to the kidneys caused by general nephrotoxic drugs. The endogenous creatinine clearance rate is a reliable method for measuring renal function. It is inversely related to the half-life (t1/2) of drugs. For example, the t1/2 of a major drug excreted by the kidneys is 1 hour in normal individuals; when renal function is reduced to 50% of normal, the t1/2 is 2 hours; when the endogenous creatinine clearance rate is 25% of normal, the t1/2 is 4 hours.
Common Chinese medicines that affect renal function
There are many varieties of Chinese medicines with complex compositions, and some Chinese medicines contain biotoxins that can cause harm if used improperly. Although the mechanism of adverse reactions caused by many Chinese medicines is still unclear, it is important to know which drugs can cause renal damage, their main clinical manifestations, and pathological changes, which are important for preventing and detecting drug-induced organ damage.
(1) Plants
1. Containing alkaloids
In recent years, it has been discovered that not only Tripterygium wilfordii, Veratrum nigrum, Leonurus heterophyllus, Ricinus communis, Ephedra sinica, Platycodon grandiflorus, and other Chinese herbal medicines can cause acute renal failure, but also some preparations containing these Chinese herbal medicines can cause renal damage or even acute renal failure. For example, preparations containing Tripterygium wilfordii such as Tripterygium wilfordii tablets, Tripterygium wilfordii total glycosides, and Kunming Shanhaitang tablets can cause hematuria, proteinuria, urinary casts, lower back pain, and renal percussion pain when the dosage is slightly higher. Acute renal failure with oliguria can occur a few days after taking the medicine. The dosage should be strictly controlled in clinical applications, and caution should be exercised or avoided in patients with existing renal insufficiency.
2. Containing other components
Stephania tetrandra, Caulis sinomenii, Cyathula officinalis, etc., all contain aristolochic acid, which can cause renal tubular necrosis, leading to facial edema, progressive systemic edema, frequent urination, urgency, and even acute or chronic renal failure and uremia. Patients should follow the doctor's advice and avoid using these drugs in patients with renal insufficiency.
In addition, in recent years, it has been reported that Chinese patent medicines such as Huoxiang Zhengqi pills, Yunnan Baiyao, Gegen Su injection, and compound Danshen injection can also cause acute renal failure.
(2) Animals
1. Scorpion
Scorpions have extremely strong nephrotoxicity, mainly containing scorpion acid anhydride. Excessive ingestion, external use, or improper pharmaceutical use can cause poisoning. Due to its strong toxicity and rapid onset, if not treated in time, it can lead to incomplete recovery of renal function or even death.
2. Fish gallbladder
Fish gallbladder from toxic fish contains bile toxins, which can reduce the activity of cytochrome oxidase in organs such as the liver, kidneys, and brain, inhibit cellular oxidative phosphorylation, and cause extensive toxic necrosis of the liver, kidneys, and brain. Due to acute hepatic failure, bile toxins replace norepinephrine, leading to vasodilation, decreased effective blood volume, insufficient renal blood flow, and oliguria or anuria, thereby promoting renal failure.
3. Seahorse
Also known as water horse or horse-headed fish, seahorses are warm in nature and enter the kidney meridian. They have the functions of warming the kidneys and invigorating yang, promoting blood circulation, and dispelling stasis. The extract contains androgens and is used to treat kidney yang deficiency. Overuse can cause skin purpura, proteinuria, and renal dysfunction.
4. Others
Centipedes, bee venom, etc., also have nephrotoxicity, and their use should be strictly limited. The Chinese patent medicines that can cause acute renal failure include Niuhuang Jiedu tablets, Angong Niuhuang pills, Mawan pills, and Huichong San. For such drug poisoning, if detected early and treated in a timely manner, the majority of patients can fully recover. Immediate gastric lavage should be performed to remove residual toxins, and in addition to supportive therapy, adrenocortical hormones can be used to alleviate toxemia or allergic reactions. Early and timely dialysis should be performed.
(3) Minerals
1. Containing arsenic
Arsenolite, realgar, orpiment, green vitriol, as well as Chinese patent medicines such as Niuhuang Jiedu tablets, Angong Niuhuang pills, Niuhuang Qingxin pills, Liushen pills, and Pizao San, all contain arsenic. After ingestion, they can hydrolyze to generate trivalent arsenic ions, which have various toxic effects on the body. First, they harm nerve cells, leading to central nervous system poisoning and a series of toxic symptoms. Clinical manifestations include severe nausea, vomiting, abdominal pain, diarrhea, elevated transaminases, jaundice, hematuria, proteinuria, and liver and kidney damage.
2. Containing mercury
Mercury sulfide, mercury sublimate, cinnabar, red powder, as well as Chinese patent medicines such as Angong Niuhuang pills, Niuhuang Qingxin pills, Zhusha Anshen pills, Tianwang Buxin pills, Anshen Bunao pills, Suhe Xiang pills, Renshen Zaizao pills, and Dahuo Luo pills, all contain mercury. After ingestion, they can hydrolyze to generate divalent mercury ions, which are rapidly distributed to various organs and tissues after absorption by the body. They can also penetrate the blood-brain barrier and enter brain tissue. Excessive use can cause various toxic symptoms. The urinary system manifestations include oliguria, proteinuria, and in severe cases, acute renal failure.
Prevention and treatment principles for Chinese medicine-induced renal injury
To prevent drug-induced renal injury, strict control of the indications for drug use is the first step to avoid misuse. The following points should also be taken into consideration.
1. Pay attention to the dosage and treatment duration of drugs, and closely monitor urinary enzymes, urinary proteins, and renal function during drug use. For some high-risk patients with renal damage, drugs should be used with caution or reduced dosage. For example, infants, malnourished individuals, and patients with renal insufficiency should avoid using drugs of this kind; if necessary, the dosage should be reduced or the dosing interval extended according to the specific situation.
2. When using multiple drugs, pay attention to drug interactions.
3. Some Chinese herbs have specific decoction time requirements. For example, the longer the decoction time for Stephania tetrandra, the stronger the toxic effect. Therefore, it is important to understand the decoction time for different Chinese herbs. Improper selection of decoction utensils can also cause toxicity, so aluminum pots and iron pots should be avoided for decoction.
4. If long-term use of a certain type of Chinese medicine is necessary due to a chronic disease, for drugs that may accumulate, the method of using small amounts intermittently should be adopted. Chinese medicines containing metal ore components are generally excreted very slowly. Even with a small dosage, they can easily accumulate and cause renal damage if used for a long time.
5. Once renal damage is detected, the drug should be immediately discontinued, and appropriate treatment should be given based on the specific type of drug and its clinical manifestations.
