Do not drive or do anything else that could be dangerous until you know how this medicine affects you. Tell your doctor right away if you or your child have a rash, itching, hoarseness, trouble breathing, trouble swallowing, or any swelling of your hands, face, or mouth after using this medicine. Phenytoin is constantly finding equilibrium binding and unbinding to proteins. Phenytoin may cause heart problems, including a slow heartbeat. Patients at increased risk for hypoglycemia (e.g., the elderly or patients with renal impairment) should be started on 1 mg once daily After reaching a daily dose of 2 mg, further dose increases can be made in increments of 1 mg or 2 mg based upon the patient's glycemic response. So above Km concentrations, you’re starting to approach max velocity of elimination and curve flattening, which is when it switches over to a constant amount being metabolized. Anyway. If you remember nothing else from this post, take this away:Phenytoin is metabolized by several CYP enzymes (mainly 2C19, and 2C9, but a little of 3A4 too), and so there are multiple medications that can affect its metabolism.So regardless of mechanism of altered phenytoin concentrations (aka changes in distribution versus metabolism), see below for a sampling of medications that can affect phenytoin serum concentrations:Although the focus for this post is on phenytoin dosing, it’s hard to mention drug interactions of phenytoin and ONLY discuss the ones that affect phenytoin. What you should take away from this is that while the concentration of unbound drug is low, the rate of hepatic metabolism is BUT, as you add more drug (aka move right along the x axis and increase intracellular drug concentration), the rate of hepatic metabolism slows, which is why the curve flattens. and formulary information changes. Amaryl does not treat type 1 diabetes. Phenytoin can temporarily lower the number of white blood cells in your blood, increasing the chance of getting an infection. Contact the applicable plan And secondly, fosphenytoin, like Anakin, is just plain nicer than its counterpart (at least in terms of administration).You can see from this table that fosphenytoin offers increased flexibility in route and rate of administration, as well as better compatibility with fluids. If you log out, you will be required to enter your username and password the next time you visit. Increasing concentrations of drug means increasing t1/2, so it can range anywhere from 7-42 hours! Instructions on Amaryl (method and dosage) Tablets are intended for internal use, in whole, without chewing and drinking plenty of fluid. Some drugs compete with phenytoin for its protein hiding spots, and there are many that displace phenytoin from albumin (Also, be aware of drug/nutrient interactions that can inhibit absorption of PO phenytoin doses…Drug interactions also play a role in the metabolism and drug out considerations for phenytoin. Available for Android and iOS devices. It’s like the Anakin to Darth Vader. 100mg phenytoin sodium (capsules/injection) = 90 mg phenytoin base9,10 (suspension) Suspension (90mg/5mL) is available for NG administration or those with swallowing problems. If this occurs, there are certain precautions you can take, especially when your blood count is low, to reduce the risk of infection or bleeding:This medicine may decrease bone mineral density. Common glimepiride side effects include dizziness, headache, nausea, vomiting, rash, allergic reactions, and flu-like symptoms. These may be symptoms of a serious and life-threatening condition called drug reaction with eosinophilia and systemic symptoms (DRESS). Patients with risk factors for hypoglycemia, such as the elderly, may be started at 1 mg PO once daily. If the phenytoin concentration is 7-12 mcg/mL, the dose may be increased by 50 mg/day. Diseases & Conditions And then you’ll have supratherapeutic levels...and potentially a somnolent princess with twitchy eyes! If you or your child have any questions about this ask your doctor. Up to 90-95% of the drug can be attached to proteins like albumin. Even though it is not quite as highly utilized in recent years due to the emergence of simpler, relatively happy-go-lucky drugs like levetiracetam and lacosamide, it is still very much on the bench and often called up to play.Like many other anti-epileptic drugs (AEDs), we don’t reeeeally know exactly how phenytoin works… What we do know is it affects the transport of sodium ions across cell membranes.And if you go WAY back to biochemistry, remember sodium influx from the outside to the inside of the cell is what starts action potential propagation.Here’s a look at the general action potential with electrolyte movement noted:Now let’s take a look at how that relates to the depolarization and repolarization of a neuron:And finally, let’s relate this to how action potentials move throughout a neuron:So to summarize, by either slowing sodium influx into the cell or expediting efflux out of the cell (unknown how much of either), phenytoin slows action potentials.