Can't Maintain Dilantin Level!

[jstkathy5]

I'm hoping someone here can shed some light on this.

I've read that it's sometimes difficult to some people to maintain their theraputic levels of Dilantin despite 100% compliance. 30 years ago I was taking Dilantin and doing well but could not maintain the theraputic levels for very long. But since I was doing well, my doc kept me on it. Evenutally I was taken off of it and put on several other meds.

I've been back on Dilantin again for about 9 mos and am having the same problem.

Despite full complaince, I can't maintain a level between 10-20. I'll start at 12, doc is happy, I feel good, then a month or so later, I feel crappy, having partials, we do another level, and I'm 8.

Did anyone else have this problem? I'm taking 500 mg daily now and he doesn't want to go up. He's on vacation right now, so when he get's back I know I'm gonna hear from him because my level is down again. ::sigh::

I like Dilantin. I have no side effects from it. I'd hate to have to switch again. This is heart breaking.

[bezara]

are you taking other medications tthat interact with dilantin?
from rxllist.com i got the following information
There are many drugs which may increase or decrease phenytoin levels or which phenytoin may affect. Serum level determinations for phenytoin are especially helpful when possible drug interactions are suspected. The most commonly occurring drug interactions are listed below:
1. Drugs which may increase phenytoin serum levels include: acute alcohol intake, amiodarone, chloramphenicol, chlordiazepoxide, diazepam, dicumarol, disulfiram, estrogens, H2-antagonists, halothane, isoniazid, methylphenidate, phenothiazines, phenylbutazone, salicylates, succinimides, sulfonamides, tolbutamide, trazodone.
2. Drugs which may decrease phenytoin serum levels include: carbamazepine, chronic alcohol abuse, reserpine, and sucralfate. 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.
3. Drugs which may either increase or decrease phenytoin serum levels include: phenobarbital, sodium valproate, and valproic acid. Similarly, the effect of phenytoin on phenobarbital, valproic acid and sodium valproate serum levels is unpredictable.
4. Although not a true drug interaction, tricyclic antidepressants may precipitate seizures in susceptible patients and phenytoin dosage may need to be adjusted.
5. Drugs whose efficacy is impaired by phenytoin include: corticosteroids, coumarin anticoagulants, digitoxin, doxycycline, estrogens, furosemide, oral contraceptives, quinidine, rifampin, theophylline, vitamin D.

[Kathrine]

Hi Kathy



Are you taking generic or brand name dilantin?




...

[jstkathy5]

Bezara: Thank you for that information! It was great! The only other medication I take is Actos and Glipizide (for diabetes) and they were not mentioned.

Katherine: Bottle says "Dilantin Kapsules" (no reference to 'generic for' on the bottle). I hadn't thought about that as a possibility, but it appears I am not using a generic for Dilantin.

::sigh::

[linniec]

Dear 1stKathy,
Katherine's right. Generic Dilantin is something to be wary of. You quote the bottle as being labeled "Dilantin Kapsules"
The brand-name Dilantin, is now owned by Pfizer (they absorbed Parke Davis who originally marketed Dilantin. ) The brand-name Dilantin is sold as Dilantin Capsules, Kapseals, or Infatab. Sometimes your health plan, not knowing any better, will substitute a generic for brand-name Dilantin .
The word Kapsules does not belong to Pfizer-Parke Davis.
As Katherine said,The blood levels of someone getting generic Dilantin could vary wildly. (Insert necessary Four letter word here.)


Linnie

[Kathrine]

Hi

I just had another thought.

When you have your levels drawn are you having it done at the same time of day each test? Levels can vary alot throughout the day depending on how long ago you took your last dose.

Kathrine

[jstkathy5]

Linne: Verrry interesting information. Thank you. I doubled checked the bottle and I was in error--the spelling is as you stated "Kapseal" not as I wrote "Kapsule". Minor difference in spelling but could have had a huge difference in meaning. Thank you again for that.

Katherine: Yes, I am having them around the same time, however, and you have again brought up a very important point, I do not always take them at the same time. Ah ha! Soooooo, if I took my last dose at 9 PM and then tested at 2 PM, the levels may be different than if I took my last dose at 1 AM and tested at 2 PM.

I finally got a call back from the 'doctor on call's nurse who gave me the following instructions. "Take your usual 500 tonite at bedtime then take another 200 when you get up in the morning. Continue the 500 at bedtime and 200 in the morning for five (5) consequtive days. The doctor wants to jump start your levels; get them higher, then you and your doctor can discuss it on Monday."

Yikes! Another 200 on top of my 500? Good grief. But my level's are falling from 12 to 9 on 500, so I guess 700 on a 'temp' basis can't be that bad. Still scares me.

Thanks so much ladies for your input and support.

[bezara]

kathy you are welcome . i did some more internet search for the drug intaraction about the medicines that you take. and i found the following info
Drug-Drug Interactions

phenytoin and glipiZIDE (moderate Drug-Drug)
Description:
MONITOR:
The coadministration with phenytoin may diminish the hypoglycemic effect of sulfonylureas. Phenytoin has been reported to cause hyperglycemia, hypoinsulinemia and glucose intolerance, thus it may interfere with blood glucose control. Conversely, some sulfonylureas may enhance the plasma concentrations and pharmacologic effects of phenytoin by competitive inhibition of its metabolism by CYP450 2C9 and/or 2C19 isoenzymes. Phenytoin intoxication has been reported during coadministration with tolbutamide specifically.
MANAGEMENT:
Consideration should be given to more closely monitoring blood glucose and phenytoin levels during coadministration with sulfonylureas. Patients should be advised to notify their physician if loss of glycemic control occurs or if they experience symptoms of possible phenytoin toxicity, including drowsiness, visual disturbances, change in mental status, seizures, nausea, and ataxia.


iphenytoin and pioglitazone (moderate Drug-Drug)
Description:
MONITOR:
Pioglitazone is metabolized by CYP450 3A4 microsomal enzymes in the liver. The clinician should be aware of the potential for an interaction when pioglitazone is used in combination with another medication that induces CYP450 3A4.
MANAGEMENT:
The patient should be observed for clinical and laboratory evidence of altered safety and efficacy of both drugs if pioglitazone is added to or removed from the patients medication regimen. Patients should be advised to report loss of blood sugar control to their physician.




Drug-Food Interactions

phenytoin (moderate Drug-Food)
Description:
ADJUST DOSING INTERVAL: Phenytoin bioavailability may decrease to subtherapeutic levels when the suspension is given concomitantly with enteral feedings. The mechanism may be related to phenytoin binding to substances in the enteral formula (e.g., calcium, protein) and/or binding to the tube lumen. Data have been conflicting and some studies have reported no changes in phenytoin levels, while others have reported significant reductions. MANAGEMENT:
Some experts have recommended interrupting the feeding for 2 hours before and after the phenytoin dose, giving the phenytoin suspension diluted in water, and flushing the tube with water after administration; however, this method may not entirely avoid the interaction and is not always clinically feasible. Patients should be closely monitored for clinical and laboratory evidence of altered phenytoin efficacy and levels upon initiation and discontinuation of enteral feedings. Dosage adjustments or intravenous administration may be required until therapeutic serum levels are obtained.

pioglitazone (moderate Drug-Food)
Description:
MONITOR:
Grapefruit juice may increase the plasma concentrations of some orally administered drugs that are substrates of the CYP450 3A4 isoenzyme. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruits. The extent and clinical significance are unknown. Moreover, pharmacokinetic alterations associated with interactions involving grapefruit juice are often subject to a high degree of interpatient variability.
MANAGEMENT:
Patients who regularly consume grapefruits and grapefruit juice should be monitored for adverse effects and altered plasma concentrations of drugs that are metabolized by CYP450 3A4. Grapefruits and grapefruit juice should be avoided if an interaction is suspected. Orange juice is not expected to interact with these drugs.
hope this helps

[jstkathy5]

Thank you again Bezara. That was very kind of you.

~Kathy~

[bezara]

you are very welcome. if you have more questions please do not hesitate to ask. also you may want to search on the internet about drug- helrb-supplements interactions checking websites if you are taking any health food herbs or supplements. because we are responsible to our bodies