三甲双酮（三甲氧唑双酮，解痉酮） 　　
英文名称：Trimethadione(Troxidone,Tridione) 　　
结构： 　　

性质：
本品为无色或白色结晶；分子量为143.15，熔点46℃，沸点79℃，微具樟脑味，味微苦。溶于水，易溶于乙醚、乙醇和氯仿。　
作用与作用机制： 　　
本品能提高电惊厥阈值，对抗戊四氮惊厥，对于癫痫小发作作用较好。三甲双酮能降低大脑皮层和间脑兴奋性，缩短其后放电活动。可能直接作用于原发性病灶，对癫痫大发作效果好。本药很快由胃肠道和其他部位吸收，分布在体液中，不与蛋白结合，在肝脏被微粒体去甲基化成二甲酮和相应的双甲酮代谢产物。两种代谢物均有抗癫痫活性，三甲酮和去甲基对甲酮均由尿中排出，每日排出35%-40%，几乎无药物原形由尿排出。　
药动学： 　　
本品口服后血浆蛋白结合不明显。作用开始慢，有效血药浓度为20μg/ml，半衰期为16-20h。在肝脏内代谢，其代谢产物二甲双酮（dimethadione）也有抗癫痫活性，半衰期达240h,有效血浓度为700μg/ml。代谢物与少量原形药物从尿中排出。 　　
注意事项： 　　
不良反应较大，常见的有嗜睡、乏力、恶心、皮疹、脱发、畏光、昼盲等。还可引起白细胞和血小板减少、再生障碍性贫血、剥脱性皮炎、红斑狼疮、肾病综合征、肝炎、肌无力等。本品有致畸作用。急性中毒可见共济失调、视物障碍及昏迷。治疗中如有严重不良反应，须立即停药。孕妇及肝、肾和造血功能不全禁用。 　　
临床应用： 　　
本品用于治疗难于治愈的癫痫小发作，如伴有大发作时，需与适量的抗大发作药物合用。因毒、副反应大，目前已不多用。 　　
用法计量： 　　
口服：抗癫痫，成人，开始剂量900mg/d，分次服用，根据病情每周增加300mg，直至1.8g/d。儿童，2岁以下300mg/d；2-6岁600mg/d，分次服用。 　　
制剂： 片剂：150mg；胶囊剂：300mg。

Trimethadione is used to control absence ("petit mal") seizures.

Trimethadione may also be used for purposes other than those listed in this medication guide.

What is the most important information I should know about Tridione (trimethadione)?

Do not stop taking this medication even if you feel better. It is important to continue taking trimethadione to prevent the seizures from recurring.

Carry or wear a medical identification tag to let others know that you are taking this medicine in the case of an emergency.

Use caution when driving, operating machinery, or performing other hazardous activities. Trimethadione may cause dizziness or drowsiness. If you experience dizziness or drowsiness, avoid these activities.

What should I discuss with my healthcare provider before taking Tridione (trimethadione)?

Before taking trimethadione, tell your doctor if you have

• liver disease;
• kidney disease;

• retinal or optic nerve (eye) disease;

• a disease of the blood or bone marrow; or

• acute intermittent porphyria.

You may not be able to take trimethadione, or you may require a dosage adjustment or special monitoring during treatment if you have any of the conditions listed above.

Trimethadione is in the FDA pregnancy category D. This means that it is known to be harmful to an unborn baby. Malformations of the face and head, heart, and nervous system have been reported. Do not take trimethadione without first talking to your doctor if you are pregnant or could become pregnant during treatment. It is not known whether trimethadione passes into breast milk and how it might affect a nursing infant. Do not use this medication without first talking to your doctor if you are breast-feeding a baby.

How should I take Tridione (trimethadione)?

Take trimethadione exactly as directed by your doctor. If you do not understand these directions, ask your pharmacist, nurse, or doctor to explain them to you.

Take each dose of trimethadione with a full glass of water.

Trimethadione can be taken on an empty stomach or with food to decrease stomach upset.

Chew the chewable tablets before swallowing them.

To ensure that you get a correct dose, measure the liquid form of trimethadione with a special dose-measuring spoon or cup, not with a regular table spoon. If you do not have a dose-measuring device, ask your pharmacist where you can get one.

Carry or wear a medical identification tag to let others know that you are taking this medicine in the case of an emergency.

Do not stop taking this medication even if you feel better. It is important to continue taking trimethadione to prevent the seizures from recurring. Store trimethadione at room temperature away from moisture and heat.

What happens if I miss a dose?

Take the missed dose as soon as you remember. However, if it is almost time for the next dose, skip the dose you missed and take only the next regularly scheduled dose. Do not take a double dose of this medication.

What happens if I overdose?

Seek emergency medical treatment.

Symptoms of a trimethadione overdose include dizziness, drowsiness, poor coordination, nausea, vomiting, and changes in vision.

What should I avoid while taking Tridione (trimethadione)?

Do not drink alcohol while taking this medication. Alcohol can cause deep sedation or sleepiness. It may also increase the risk of having seizures. Use caution when driving, operating machinery, or performing other hazardous activities. Trimethadione may cause dizziness or drowsiness. If you experience dizziness or drowsiness, avoid these activities. Avoid prolonged exposure to sunlight. Trimethadione may increase the sensitivity of the skin to sunlight. Use a sunscreen and wear protective clothing when sun exposure is unavoidable.

Tridione (trimethadione) side effects

If you experience any of the following serious side effects, stop taking trimethadione and seek emergency medical attention or contact your doctor immediately:

• an allergic reaction (difficulty breathing; closing of the throat; swelling of the lips, tongue, or face; or hives);

• a rash;

• worsening of seizures;

• sore throat or fever;

• changes in vision;

• easy or unusual bleeding or bruising;

• bleeding nose; or

• extreme drowsiness or dizziness.

Other, less serious side effects may be more likely to occur. Continue to take trimethadione and talk to your doctor if you experience

• mild dizziness, poor coordination, or drowsiness;

• blurred or double vision, or irregular back-and-forth movements of the eyes;

• decreased appetite, nausea, or vomiting; or

• increased sensitivity of the skin to sunlight.

Side effects other than those listed here may also occur. Talk to your doctor about any side effect that seems unusual or that is especially bothersome.

What other drugs will affect Tridione (trimethadione)?

Trimethadione may increase the effects of other drugs that cause drowsiness, including antidepressants, alcohol, antihistamines, pain relievers, anxiety medicines, other seizure medicines, and muscle relaxants. Dangerous sedation, dizziness, or drowsiness may occur if trimethadione is taken with any of these medications. Tell your doctor about all medicines that you are taking, and do not take any medicine without first talking to your doctor.

Drugs other than those listed here may also interact with trimethadione. Talk to your doctor and pharmacist before taking any prescription or over-the-counter medicines, including herbal products.

Where can I get more information?

• Your pharmacist has additional information about trimethadione written for health professionals that you may read.

What does my medication look like?

Trimethadione is available with a prescription under the brand name Tridione as 150 mg chewable tablets, as 300 mg capsules, and as a solution with a strength of 40 mg/mL. Other brand or generic formulations may also be available. Ask your pharmacist any questions you have about this medicine, especially if it is new to you.