Droxidopa is a generic form of the brand-name drug called Northera. This prescription medication was first approved by the FDA in 2014 for treating the symptoms of neurogenic orthostatic hypotension (NOH), which involves fainting, dizziness, or lightheadedness when standing after sitting or lying down. Droxidopa is a type of prodrug (a drug that is converted into an active form once it reaches its target area) and belongs to the class of alpha and beta-adrenergic agonists.
与专家讨论共付额援助
这种药物的作用是暂时提高体内去甲肾上腺素的水平，从而调节站立血压。去甲肾上腺素，又称去甲肾上腺素，是一种调节血压所需的神经递质（脑化学物质）。
Droxidopa is available in oral capsule form and can only be obtained via a doctor’s prescription.
Droxidopa 用于治疗什么？
Droxidopa is used to treat symptomatic neurogenic orthostatic hypotension – a chronic and potentially debilitating condition characterized by a sustained drop of blood pressure upon standing due to low production or release of norepinephrine. This condition may arise as a result of autonomic failure and mainly occurs in patients suffering from certain neurologic disorders such as pure autonomic failure (PAF), multiple system atrophy (MSA), and Parkinson’s disease (PD).
These neurologic disorders mainly affect the patient’s 自主神经系统 （通常参与调节各种非自主功能，例如心率、呼吸和血压），导致去甲肾上腺素释放不足。去甲肾上腺素释放失调导致神经源性OH患者站立时血压降低。
由于血压下降，神经性OH患者会出现严重头晕、头昏、晕厥、视力模糊、昏厥（昏厥感）和失去意识。
Between 80,000 – 150,000 people are thought to suffer from the symptoms of neurogenic OH in the United States.
How Does Droxidopa Work?
Droxidopa works to improve the symptoms of NOH by increasing the norepinephrine level in the body. Norepinephrine, upon release, normalizes the blood pressure by constricting (narrowing) the peripheral blood vessels.
作用机制
Once inside the body, droxidopa prodrug is converted into norepinephrine by an enzyme called dopa-decarboxylase. Norepinephrine then exhibits its pharmacological action throughout the body and increases blood flow to the brain, which prevents the symptoms of NOH.
剂型和规格
Droxidopa is available in capsule form with strengths of 100 mg, 200 mg, and 300 mg.
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Droxidopa剂量
剂量信息
The recommended initial (starting) dose is 100 mg 3 times a day during waking hours (in the morning, at midday, and in the late afternoon at least 3 hours before bedtime). The dose of droxidopa is titrated (adjusted) according to symptomatic response (where the patient’s symptoms respond to the drug).
Depending on the symptomatic response, the droxidopa dose can be increased by increments of 100 mg 3 times a day, up to a maximum dose of 600 mg three times a day. The maximum recommended total daily dose of droxidopa is 1,800 mg. Dose titration and adjustment must be done by the treating doctor.
屈昔多巴的剂量因患者而异，并且以非常严格的方式进行，以改善神经性 OH 症状并避免血压过度升高。
如果漏服了剂量该怎么办
Take your dose consistently as prescribed by your doctor. In case of a missed dose, avoid taking a double dose of droxidopa to compensate for the missed dose.
If you accidentally took your dose less than 3 hours before bedtime, consult your healthcare provider immediately to reduce the risk of supine hypertension.
How Is Droxidopa Used?
Droxidopa capsules are taken orally (by mouth). Since the elimination half-life of this medication is 2 to 3 hours, it is prescribed to be taken three times a day to maintain a consistent effect.
Droxidopa capsules should be taken consistently with or consistently without food upon waking up in the morning, at midday, and in the late afternoon at least 3 hours prior to bedtime. The capsules should be swallowed whole without opening, crushing, chewing, or breaking them.
Possible Side Effects of Droxidopa
服用屈昔多巴的患者报告的一些常见副作用包括但不限于：
- 恶心
- 头晕
- 头痛
- 高血压（血压升高）
These symptoms are temporary and can be managed easily. However, if the symptoms persist and do not go away within two weeks during therapy, you should report to your healthcare provider immediately.
此外，一些副作用可能很严重，需要立即就医，例如：
卧位高血压
Droxidopa can cause or worsen supine hypertension in NOH patients. Supine hypertension is a condition in which a patient’s blood pressure rises when they lie flat on their back. Supine hypertension increases the risk of stroke if not appropriately managed.
Doctors recommend that patients should check their blood pressure before going to bed, and while resting or sleeping, they should elevate the head of the bed to avoid the risk of supine hypertension. Blood pressure should also be monitored whenever changing the dose.
心律失常、充血性心力衰竭和缺血性心脏病
Droxidopa therapy may exacerbate existing arrhythmias, congestive heart failure, and ischemic heart disease. It is recommended to discuss your health status with your doctor before initiating droxidopa.
严重过敏反应
Droxidopa contains tartrazine (a lemon yellow azo dye used in food coloring and medication), which may cause a severe allergic reaction (including bronchial asthma) in some patients with NOH.
高热和意识混乱
在上市后监测中，接受屈昔多巴治疗的患者还报告了高热（体温超过 106.7 华氏度的症状）和意识模糊症状。
Therefore, it is recommended to carefully observe the patients when the dosage is changed.
Ask a Specialist About Side Effects
Droxidopa Interaction With Other Drugs
There is a high possibility that other drugs may interact with droxidopa and increase the risk of supine hypertension in patients with NOH. Some of the medications that need to be avoided or adjusted include:
- Norepinephrine
- Ephedrine
- Midodrine
- Triptans
- Dopa-decarboxylase inhibitors
- MAO inhibitors and linezolid
- Vitamins and herbal products
Before taking droxidopa, consult your healthcare provider if you take the medications mentioned above. You should always inform your doctor and pharmacist about all the medications you’re currently taking before starting any new medications.
防范措施
It is recommended to consult your doctor before taking droxidopa. You should not take droxidopa in the following cases:
- You have a history of asthma, irregular heartbeat, heart failure, and kidney disease.
- You are pregnant or planning to become pregnant.
- You are breastfeeding a child or plan to breastfeed.
- You are less than 18 years old.
US Boxed Warning – Supine Hypertension
Monitor supine blood pressure prior to and during treatment and more frequently when increasing doses. Elevating the head of the bed lessens the risk of supine hypertension, and blood pressure should be measured in this position. If supine hypertension cannot be managed by elevation of the head of the bed, reduce or discontinue droxidopa.
参考：
- Kaufmann, H., Norcliffe-Kaufmann, L., & Palma, J. A. (2015). Droxidopa in neurogenic orthostatic hypotension. Expert review of cardiovascular therapy, 13(8), 875-891.
- Kaufmann, H., Freeman, R., Biaggioni, I., Low, P., Pedder, S., Hewitt, L. A., … & Mathias, C. J. (2014). Droxidopa for neurogenic orthostatic hypotension: a randomized, placebo-controlled, phase 3 trial. Neurology, 83(4), 328-335.
- US. Food and Drug Administration. Droxidopa prescribing information https://www.accessdata.fda.gov/drugsatfda_docs/label/2014/203202lbl.pdf
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