Pain is a hard thing to bear. No matter what part of the body feels pain, it can make people feel very uncomfortable. For a person who feels pain physically, it is very important to find the right analgesic. So, do you know all these things about analgesics?

1、 Can trigeminal neuralgia be relieved by taking painkillers?

Trigeminal neuralgia can be relieved partly by taking painkillers.

Repeated, transient and paroxysmal pain in the distribution area of facial trigeminal nerve is called trigeminal neuralgia, also known as painful convulsion. Often fall ill after 40 years old, and more and more women. It is often caused by nerve root or semilunar ganglion compression, trigeminal sensory nerve root or brainstem sensory nucleus invasion. Some severe cases may not be relieved by taking painkillers, and need surgical treatment, radiofrequency ablation, or local nerve block treatment. The commonly used drugs for relieving trigeminal neuralgia are carbamazepine, oxcarbazepine and phenytoin sodium, which are generally suitable for mild patients. Patients with trigeminal neuralgia generally show tingling and throbbing pain, which lasts for a short time, ranging from a few seconds to 1 to 2 minutes, and can suddenly stop. It can occur several times a day or 10 times or even hundreds of times. Some patients may have trigger points. Trigeminal neuralgia needs drug treatment first. Generally, some patients can improve their symptoms only after taking drugs, but patients with ineffective drug treatment need radiofrequency thermocoagulation or surgery; In addition, if the patient’s trigeminal neuralgia is caused by a primary disease such as arteriosclerosis, the doctor will help the patient alleviate the symptoms by treating the primary disease. After routine treatment, systemic pain can be controlled.

Provide patients with a quiet and comfortable rest environment to ensure that patients have full rest and reduce pain. By listening to music, guiding imagination, reading newspapers and other methods, we can relax our body and mind, divert our attention, improve pain threshold and reduce pain. Avoid improper face washing, tooth brushing, shaving, etc. to avoid pain. Patients should choose light, nutritious and non irritating soft food. In severe cases, patients may enter a semi liquid or liquid diet. When chewing, move gently. Eat soft food and swallow with a small mouth to avoid causing pain. Avoid eating food that is not easy to digest, and try to reduce barbecue, smoking, pickled food and food that is easy to produce gas, such as carbonated drinks, coffee, bananas, broad beans, etc.

Classification of analgesics

Analgesics can be divided into four categories according to their sources: natural alkaloids (morphine), semi synthetic analgesics (codeine), total synthetic analgesics (pethidine) and endogenous polypeptides (enkephalin).

Structural characteristics of analgesics

Morphine analgesia mainly combines with opioid receptors with three-dimensional structure in the body and produces interaction. Morphine and its synthetic substitutes have the same pharmacodynamic conformation, according to which an opioid receptor model is proposed:

(1) The flat aromatic ring structure interacts with the receptor flat region through van der Waals force.

(2) The alkaline center can be partially ionized into positive ions under physiological pH, so as to combine with the anion site on the surface of the receptor.

(3) In the groove part, the ethylene base of piperidine ring protrudes before the plane, and is adapted to the hole on the receptor in a suitable direction.

According to this model, morphine and its synthetic substitutes must have the following structural characteristics:

(1) There is a flat aromatic ring structure in the molecule, which interacts with the receptor flat region through van der Waals force.

(2) It has an alkaline center and can be partially ionized into positive ions under physiological pH, so as to combine with the anion site on the surface of the receptor.

(3) The benzene ring in the molecule is connected with the piperidine ring by an upright bond, so that the basic center and the benzene ring are on the same plane, so as to bind with the receptor; The ethylene group of the piperidine ring protrudes before the plane and is adapted to the holes on the receptor in one direction.

The structure-activity relationship study also found that not only the structure of morphine derivatives can meet the above requirements, but also the synthetic substitutes with simple structures can meet all or part of the conformational requirements.

2、 What painkillers can you take for stubborn pain of lower limbs?

Patients with persistent limb pain can generally take anti-inflammatory and analgesic drugs or neurotrophic drugs.

Patients can usually take anti-inflammatory and analgesic drugs or neurotrophic drugs, as follows. 1. Anti inflammatory and analgesic drugs. In most cases, leg pain is caused by aseptic inflammation. Patients can take ibuprofen, diclofenac sodium, losoprofen sodium, celecoxib, etocoxib, etc. orally under the guidance of doctors. 2. Neurotrophic drugs, such as mecobalamin, cobalamin adenosine or vitamin B12, can nourish the nerve myelin sheath and avoid accelerated neurodegeneration. While taking oral medicine, patients can also relieve symptoms by combining external plaster, functional exercise, physical therapy and other methods. Patients with obstinate pain in lower limbs should go to the hospital to find out the cause of pain, and treatment can gradually improve joint or muscle pain. In most cases, leg pain is caused by osteoarthritis, calf soft tissue pain, lumbar disc herniation, lumbar spinal stenosis, etc., which causes radiation pain in the lower limb nerves. Patients should choose appropriate drugs for different causes.

Lumbar disc herniation can compress nerves, causing pain in patients’ lower limbs. Patients can do lumbar CT or MRI to check whether the intervertebral disc protrudes and whether nerve compression is caused. If arterial ischemia is caused by arteriosclerosis and lower limb pain is caused, patients can do lower limb artery color ultrasound, lower limb CT angiography and other examinations to eliminate the vascular causes. Poor venous return can also cause lower limb pain. Patients need to have lower limb phlebography to check whether there is compression of iliac vein. The patient should strengthen the exercise, especially the training of the waist and back muscles. For example, the movement of small swallow flying and five point support can increase the strength of the waist and back muscles to increase the stability of the spine. At the same time, flexibility and balance training can be carried out, such as yoga, tai chi, swimming, etc., which are obviously beneficial to the neck and lumbar spine.

What are the types of synthetic analgesics?

Pethidine

Pethidine, also known as dolantin, is a phenylpiperidine derivative. It is a commonly used artificial analgesic in clinical practice. Although its structure is different from morphine, it still has the same basic structure as morphine, that is, the tertiary nitrogen in the piperidine ring, the quaternary carbon separated by two carbon atoms from the tertiary nitrogen, and the benzene ring (ring A) connected with the quaternary carbon.

“In vivo process” is easy to be absorbed by oral administration. After subcutaneous or intramuscular injection, the absorption is faster and the effect is faster. Therefore, injection is commonly used in clinical practice. The binding rate of plasma protein is about 60%, which is mainly metabolized in the liver as piperidine acid and norpiperidine, and then excreted in bound or free urine. Normeperidine has a central excitatory effect, which may be related to convulsions when poisoned. Pethidine plasma t1/2 lasted about 3 hours.

Pharmacological action

The central nervous system is similar to morphine, acting on opioid receptors in the central nervous system. 10 minutes after subcutaneous or intramuscular injection, it can produce sedative and analgesic effects, but the duration is shorter than morphine, only 2-4 hours. The analgesic effect is weaker than that of morphine. The analgesic effect of pethidine 80 ～ 100mg injected is about equivalent to that of morphine 10mg. About 10%~20% of patients showed euphoria after medication. At the equivalent analgesic dose, pethidine and morphine inhibited respiration to the same extent. It can excite the CTZ of medulla, increase the sensitivity of vestibular organs, and easily cause dizziness, nausea and vomiting.

Smooth muscle can moderately increase the tension of gastrointestinal smooth muscle and sphincter, and reduce propulsive peristalsis. However, because of its short action time, it does not cause constipation and has no antidiarrheal effect. It can cause spasm of biliary sphincter and increase pressure in biliary tract, but it is weaker than morphine. The amount of treatment had no effect on bronchial smooth muscle, while large doses caused contraction. For the uterus in the third trimester of pregnancy, it does not antagonize the role of oxytocin in stimulating the uterus, so it does not delay the labor process.

The therapeutic amount of cardiovascular system can cause orthostatic hypotension, and the cause is the same as that of morphine. The inhibition of respiration can also lead to the accumulation of CO2 in the body and the expansion of cerebral vessels, which will increase the pressure of cerebrospinal fluid.

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