By Wendy C. Brooks, DVM, DipABVP
Educational Director, VeterinaryPartner.com
Available in 250 mg and 500 mg chewable tablets, flavored oral solution; and through compounding pharmacies in assorted strength liquids and capsules
Historically, bromides were licensed and used routinely for treating seizure disorders in humans; however, when phenobarbital was introduced, the human market for bromides was completely eclipsed. Like a number of drugs introduced before modern pharmaceutical laws, potassium bromide has not yet been approved by the FDA. Drug approval is slow and costly, although both regulators and pharmaceutical companies are currently trying to speed the process. Because there is no approved product, potassium bromide is prepared by veterinary compounders. Compounding is generally regulated by individual states with varying levels of oversight; however, there is one commercially available form of potassium bromide (K-BroVet) that is prepared by a drug manufacturer licensed by the FDA and which adheres to FDA manufacturing standards.
Potassium bromide is a highly reliable anticonvulsant medication in dogs. When compared to phenobarbital, potassium bromide seems to be similarly effective and has fewer undesirable side effects. Potassium bromide may be used alone (as monotherapy) or can be combined with other anti-medications. Potassium bromide works by competing with chloride ions for access to brain tissues. As bromide levels in the brain rise and chloride levels drop, electrical activity in the central nervous system is inhibited, making the initiation of a seizure difficult.
Potassium bromide works by competing with chloride ions for access to brain tissues. As bromide levels in the brain rise and chloride levels drop, electrical activity in the central nervous system is inhibited, making it difficult to initiate a seizure.
This medication was initially reserved for dogs who either could not tolerate phenobarbital for seizure control due to unacceptable side effects or who needed additional seizure control medication beyond what their phenobarbital could provide. In fact, seizure control with potassium bromide is so effective that now many practitioners reach for it as a first-choice therapy without even using phenobarbital.
How this Medication is Used
Potassium bromide is given either as a pill or as oral liquid once daily. It can be given with or without food; however, it has a bitter flavor that can usually be masked by giving it with food.
Because it takes months to achieve a stable effective blood level of potassium bromide, many doctors will recommend a loading dose to shorten this period and get a head start on the therapeutic blood level. Using a loading dose can bring the patient to a therapeutic blood level a month sooner but the patient can be extremely sedated during the loading phase. Many doctors prefer to do the loading in a hospital setting for this reason.
Because it takes so long to reach a stable therapeutic bromide blood level, additional seizure medications may be needed, at least at first.
Potassium bromide is effective in cats but can cause a life-threatening inflammatory lung disease so it is regarded as a last choice in this species.
According to the ACVIM Consensus Statement on Seizure Management in Dogs, the first monitoring blood level should be drawn 6-12 weeks after beginning potassium bromide and annually thereafter unless there are breakthrough seizures or suspicions of toxicity.
Some nausea is associated with potassium bromide. Giving the medication with food generally controls this.
Since potassium bromide is a salt, excess thirst and urination can occur.
Drowsiness or grogginess, which can be marked, is not abnormal during a loading period when potassium bromide therapy is started. It is important not to give more potassium bromide to a groggy pet even if another dose is due.
Occasionally a dog will develop a cough that resolves when potassium bromide is discontinued.
In humans, a toxicity syndrome called bromism results when blood bromide levels become too high. Symptoms reported include: drowsiness, weakness, muscle tremors and soreness, appetite loss, constipation, and skin rashes. A similar syndrome can occur in dogs if bromide levels become too high. That’s why levels are monitored periodically.
Dogs with a history of pancreatitis may experience an exacerbation of it if potassium bromide is used to treat a seizure disorder. This is particularly true for patients taking both bromide and phenobarbital.
Interactions with other Drugs
The use of potassium bromide as a sole seizure control agent is no longer uncommon; however, the concurrent use of potassium bromide with phenobarbital allows for a reduction of phenobarbital use by 30 to 50 percent, which is usually enough to alleviate negative phenobarbital side effects. In many cases, phenobarbital can be tapered off completely without seizure recurring.
The use of diuretics (medications that lead to an increase in urine production), can wash out potassium bromide so that blood levels can drop, and potentially an increase in seizures could occur.
Concerns and Cautions
Giving potassium bromide interferes with laboratory measurement of chloride, thus any tests for chloride will be falsely elevated.
Potassium bromide does not have to be given with food but food can help mask the bitter taste and help prevent nausea, should nausea be a problem.
In cats, over one-third of patients develop a severe asthma-like lung condition. Potassium bromide is not a good choice for seizure control in cats.
Abruptly discontinuing potassium bromide can cause severe seizures. If you need to stop giving it, your veterinarian can instruct how to do so. That said, if a single dose is accidentally skipped, this is unlikely to be a problem as blood levels change so slowly. If the dose is not given at the normal time, simply give it later in the day but there is no need to double up on the next dose even if a single dose is missed all together.
Salt in food can affect bromide blood levels. Low-salt diets can lead to retaining the drug and can drive the blood level up; similarly, a salty diet can drive bromide levels down. Avoid changes in dietary salt content so that bromide levels can remain stable.
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