phenytoin and p450

I have been on Coumadin for 18 years due to Lupus Anticoagulant (Antiphospholipid Syndrome) and several DVTs. In 2005 had MI with occlusion of the LAD artery and had drug stent inserted and I am still on plavix. My doc has debated when to take me off the Plavix safely....what are the recent studies about this dilemma? thanks so much!

m not sure if you will be able to find the dosage modifications for this readily, since there may be no real concensus or standard recommendations for such. Testing for the different isotypes of the p450 enzymes is really not standard practice and different hospitals may have different protocols for this. I suggest that you ask the hospital or the doctor who requested the test since they may have their own protocol regarding tamoxifen dosage adjustment in accordance with p450 levels. Regards.

During those times I had not yet been diagnosed and was able to go back to life like normal, however after the diagnosis and being on phenytoin and switching to oxcarbazepine i am feeling awful. Dizzy, nauseated, moody, extremely tired, severe headaches that come and go. All i get from my Neurologist is these are side effects that will eventually go away. Because i never know when these symptoms will come on too strong I have missed a lot of days at work during my probation period.

This reaction is generally confined to the extremities but can affect the trunk and face and may be irreversible. Severe dermatologic reactions to phenytoin are infrequent. Some evidence, however, suggests that erythema multiforme is more likely in patients who undergo radiation therapy while receiving phenytoin.[22] Lupus-like symptoms have been described for phenytoin. Whether phenytoin administration will exacerbate preexisting idiopathic systemic lupus erythematosus (SLE) is unclear.

* buprenorphine Metabolized into norbuprenorphine by cytochrome-P450 isoenzyme 3A4 * Tyrosine kinase inhibitors, including Gleevec and Tasigna, used to treat chronic myelogenous leukemia and gastrointestinal tumors.

Folic acid supplementation in folate-deficient patients with epilepsy changes the pharmacokinetics of phenytoin, usually leading to lower serum phenytoin concentrations and possible seizure breakthrough..." It however says that initiation of Folic acid and phenytoin together is beneficial. Since you can't go back and start all over again, you can take a small dose. It has been observed that as los as 1mg dose can perturb phenytoin’s levels, You may take doses lower than 1mg/day.

Combining fluoxetine or paroxetine with phenytoin can also lead to increased phenytoin side effects and reduce blood levels of paroxetine. You really need to discuss the potential drug interactions with your own doctor.

Plavix (Clopidogrel) requires cytochrome P450 enzymes produced in the Liver, and specifically cytochrome P450 2C19. Some proton pump inhibitors (e.g. omeprazole) can reduce these enzymes making Plavix far less effective.

You should tell your doctor if you experience any of these symptoms while taking phenytoin, so that your blood level of phenytoin can be measured and your dose reduced if necessary. " Also, he has had a major surgery, and will need time to recover. However, any changes need to be reported to the doctor.

Moban® brand of molindone hydrochloride contains calcium ions which interfere with the absorption of phenytoin. Ingestion times of phenytoin and antacid preparations containing calcium should be staggered in patients with low serum phenytoin levels to prevent absorption problems”. Taken from http://www.rxlist.com/cgi/generic/phenyt_od.htm Our population is divided into 4 type of metabolizers ranging from rapid to slow metabolizers depending upon the speed of elimination of drug from body.

Thank you for your question, you are relatively fine with Phenytoin and the seizure episodes in a form of lack of speech are the residue of a generalized type seizure. I don’t have a full description of your consciousness during the lack of speech episodes to decide whether this start is a partial epilepsy which can continue in a generalized or it is a generalized one from the first moment..

Whereas if you are a chronic alcoholic, the phenytoin levels may be lower than expected and can cause seizures. I suggest you consult with your neurologist in this regard. Hope this information helps. Take care.

1) Many of the medicines used to treat epilepsy and bipolar disorder—Barbituates, Carbamazepine, Oxycarbazepine, Phenytoin, Primidone, Topiramate, Felbamate, and Lamotrigine when taken alone—make the pill, patch, ring and mini-pill less effective, increasing the chance of an accidental pregnancy. 2) There’s some evidence that these methods of birth control change the effectiveness of those particular medicines, too.

If you are pregnant your doctor may gradually decrease the dose and stop it and may prescribe an alternative anti seizure medicine which is safe during pregnancy. Sudden withdrawal of antiseizure medication may precipitate seizures in a pregnant woman which can be dangerous for the fetus. Medicines are prescribed during pregnancy only if the benefits outweigh the risks. Your doctor may prescribe you high dose folic acid 4 mg to prevent spinal cord deformities. I sincerely hope it helps.

Subsequent to discharge on 10 July, she was put on phenytoin 200 mg od. She broke out with fever again on 15 July and the fever lasted for about 4 days with daily temperature peaking in the afternoon (max 101 F). The face and body were covered with rash similar to measles which resolved by 20 July. Could she have had measles at her age? Why did she have convulsions? Could anyone throw any light on the episode.

yeah 99 days is over 3 months and 3 months is conclusive. ELISA tests for the hiv antibody in your body. alcohol doesn't affect the test or the antibodies. does this make sense? since your antibodies are unaffected by alcohol (the cytochrome P450 in your liver gets the blunt of that attack) it won't make them disappear. i hope this helps.

I totally forgot to tell you that he is on Phenytoin 100mg once daily. Can this be continued and taken for a long period of time? Thank you doctor once again for your immediate reply.

However neither interferon or ribavirin is metabolized by that particular enzyme(p450) so it is OK to drink your grapefruit juice. Stay Healthy!

can I drink the juice of 1 grapefruit a day, if I am taking metoprolol and fosinopril for blood pressure? My blood pressure is completely controled.

Does anyone know if this is a fact? I love citrus.... and I just bought a nice fresh bag last time I went shopping. Should I toss the grapefruit in the garbage?

I have had extreme fatigue and chest pains. Seeing neurologist for medicine change and have be referred to endocrinologist. How concerned should I be? What tests should be given? Is this my pituitary gland?

Addition of other antiepileptic drugs like phenytoin,lamotrigene and sedatives will be helpful for controll of his night symptoms.

m uncertain as to how the effect to tricyclics on this P450 gene relate to overall iron levels and whether they are safer or less safe than tetracyclics or SSRI's in this regard. If you could shed any light here it would be much appreciated.

Phenytoin and p450

Common Questions and Answers about Phenytoin and p450

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