What are possible complications with long-term phenytoin therapy? (Select ALL that apply.)
B. Renal dysfunction
C. Gingival hyperplasia
A, C, D. Long-term complications of phenytoin therapy can include connective tissue complications (coarsening of facial features, lip enlargement and gingival hyperplasia-good dental hygiene should be stressed), systemic lupus erythematosus (SLE), toxic hepatitis, liver damage, macrocytic anemia (due to folic acid deficiency, which should be supplemented), and osteoporosis and osteomalacia due largely to vitamin D and calcium deficiencies (which should be supplemented).
Which of the following side effects/adverse drug reactions are possible with the use of zonisamide? (Select ALL that apply.)
B. Contraindicated in sulfa allergy
C. Weight loss
D. Decreased sweating
E. Kidney stones
B, C, D, E. Zonisamide is a sulfonamide and is contraindicated in sulfonamide allergy.
Similar to topiramate except no sulfa allergy for topiramate.
A hospital pharmacist is preparing a phenytoin injection. The pharmacist should use the following diluent:
A. Lactated ringers
B. Sterile water
E. Phenytoin should be diluted in NS only. It is administered in a large vein (extravasation can cause tissue necrosis), with an inline 0.22 micron filter.
A patient has been admitted in the hospital with symptoms of acute phenytoin toxicity. Initial lab reports include a phenytoin level of 12.6 mcg/mL and an albumin level of 1.5 g/dL. Which of the following statements is accurate?
A. The albumin level is expected to be higher than reported.
B. The albumin level is expected to be lower than reported.
C. The phenytoin level is expected to be higher than reported.
D. The phenytoin level is expected to be lower than reported.
E. The phenytoin level is expected to be as reported.
Claire is a thirteen year old girl who has begun using carbamazepine therapy. She and her parents should have received counseling on these possible side effects:
A. Nausea, drowsiness, dizziness
B. Increased sodium levels.
C. Increased serum vitamin D levels.
D. Giddiness or agitated behavior
E. Insomnia, or trouble sleeping
A. Nausea, drowsiness and dizziness are more likely initially as the patient is getting used to the drug, or when receiving dose increases. A rash may be mild and transitory, or may be serious and require drug discontinuation-carbamazepine can cause Stevens Johnson Syndrome and Toxic Epidermal Necrolysis. Vitamin D and folate levels should be supplemented, if dietary intake is low, especially among females of child-bearing age. Carbamazepine can cause syndrome of inappropriate antidiuretic hormone (SIADH). This would cause low serum sodium and cognitive dysfunction (such as confusion) and is more likely when the carbamazepine level is toxic.
Many anticonvulsants deplete folic acid levels. Low folic acid levels cause risk for severe neural tube birth defects. When dispensing an anticonvulsant to a female of child-bearing age, it is a good time to ensure that folic acid intake is adequate. Which of the following suggestions might help a patient who does not consume folate-fortified food products (most commercially-prepared bread and cereal products sold in the U.S. are folate-fortified, in order to reduce the incidence of serious birth defects):
A. Eat a lot of avocados.
B. Eat a banana each day.
C. Eat a lot of white rice.
D. Eat a lot of corn tortillas.
E. Use a folic acid supplement that contains a high amount of folic acid (such as 800 mcg).
E. They may also receive a prescription dose of 1 mg from the prescriber. Some breakfast cereals are fortified with up to 400 mcg per serving. Avocados are rich in potassium. Bananas contain 20 mcg of folic acid-not a lot, but they are healthy for a variety of reasons.
A patient gave the pharmacist a prescription for Neurontin 300 mg TID #90. Which of the following is an appropriate generic substitution for Neurontin?
A. The generic name of Neurontin is gabapentin.
Choose the correct statement concerning Lamictal:
A. Reduced sweating can occur.
B. Photosensitivity from this drug requires avoidance of the sun in children.
C. It is Pregnancy Category X.
D. A slow dose titration is required, due primarily due to the risk of rash.
E. The brand name is Keppra.
D. Most of the anticonvulsants cause CNS side effects, such as ataxia, impaired concentration and dizziness. Most, including lamotrigine are also sedating; this is commonly called somnolence, or sleepiness.
A patient had several seizures when she was a young child. She is now 13 years old and has been seizure free for at least 5 years. Choose the correct statement:
A. She should continue anticonvulsant therapy until she is at least fifteen years old.
B. The drug should be discontinued immediately (stopped today) since she has been seizure-free for at least 2 years.
C. The drug can be discontinued immediately (stopped today) since she has been seizure-free for at least 3 years.
D. The drug can be discontinued immediately (stopped today) since she has been seizure-free for at least 4 years.
E. The drug should be tapered gradually to minimize the risk of seizures.
E. With all anticonvulsants, the drug should be tapered gradually (over 2 or more months) to minimize the risk of seizures. It may be possible to discontinue anticonvulsants after a seizure-free period of two to four years. In patients who had one seizure (such as someone who had an acute head injury) it may be possible to discontinue the drug if they are seizure-free for six to twelve months.
Which of the following side effects/adverse drug reactions can occur with Lamictal? (Select ALL that apply.)
A. Diplopia, blurred vision
B. Ataxia, headache
C. Sleepiness, dizziness, difficulty thinking and concentrating
D. Rash, which could become serious, and potentially, fatal
E. Interactions with many other drugs are likely.
A, B, C, D, E. Any side effects like this: Sleepiness, dizziness, difficulty thinking and concentrating...are likely if the drug is an anticonvulsant, although, depending on the agent, the degree will vary. Some of them are much worse than others; for example, with phenobarbital, the patient's mind is "numbed." A major concern with the use of anticonvulsants in children is the effect on cognitive function.
A young boy was given phenobarbital. He did not seem to be keeping up with his classmates in school. His teacher asked the father if his son “had always been a little slow.” Choose the correct statements: (Select ALL that apply.)
A. Phenobarbital can cause impaired memory and concentration, typically more so than most other anticonvulsants.
B. The parents should request a consult with a neurologist to see if the child can be switched to another drug.
C. If phenobarbital is stopped it will require a slow taper and another anticonvulsant should be brought on board concurrently.
D. In some children, phenobarbital can cause hyperactivity.
E. Phenobarbital is not a controlled substance.
A, B, C, D. Phenobarbital is a barbiturate and is C IV. It causes physical dependence and will require a taper-off. Discontinuing the drug too rapidly (or any anticonvulsant) will increase the seizure risk. If it is stopped the specialist will be titrating up another drug. Phenobarbital can lower IQ. It is an enzyme inducer; watch for drug interactions.
Choose the correct statement concerning gabapentin therapy:
A. Gabapentin is approved for epilepsy.
B. Gabapentin is approved for diabetic neuropathy.
C. Gabapentin is renally cleared and dose-adjusted at a creatinine clearance less than 10 mL/min.
D. Gabapentin frequently causes significant weight loss.
E. Gabapentin is a strong CYP 3A4 inducer.
A. Gabapentin is approved for epilepsy, restless leg syndrome and postherpetic neuralgia. It is not approved for diabetic neuropathic pain, and does not provide much benefit for this use in most patients. It is renally cleared, but both gabapentin and pregabalin (Lyrica) are dose-adjusted when the creatinine clearance is less than 60 mL/minute, which is about half of normal renal function.
Choose the correct statements concerning oxcarbazepine therapy: (Select ALL that apply.)
A. Oxcarbazepine induces the metabolism of many drugs.
B. Serious skin reactions can occur with this agent.
C. The brand name is Tegretol.
D. Dizziness, diplopia, somnolence, fatigue and nausea are possible side effects.
E. If a patient experienced hypersensitivity to carbamazepine, they should be considered at-risk for hypersensitivity with oxcarbazepine.
A, B, D, E.
Which anticonvulsant requires genetic testing prior to use in persons of Asian descent?
C. Carbamazepine has boxed warnings for serious skin reactions, including SJS and TEN: If of Asian ancestry the patient must be tested for the HLA-B 1502 allele prior to therapy; if positive, the drug cannot be used.
After Claire, a thirteen year-old girl, began to take carbamazepine, she tried to slit her wrists. Her parents were not warned to watch her for worsening mood or changes in behavior. Choose the correct statement:
A. The anticonvulsants do not carry a risk of mood changes; something else was occurring.
B. Carbamazepine makes people feel happy (slightly euphoric) and generally improves mood.
C. The anticonvulsants have a FDA warning for increased risk of suicidal ideation or behavior.
D. She should have the carbamazepine dose increased quickly to overcome this adverse effect.
E. The physician should add-on temazepam to help Claire relax when starting carbamazepine therapy.
C. Anticonvulsants have a warning concerning an increased risk of suicidal ideation or behavior; monitor for mood worsening and unusual behavior. Although the risk is low, there is an increase over placebo in mood changes among patients taking various anticonvulsants. If not warned, the caregiver or patient may not attribute the problem to the drug.
Side effects of divalproex sodium may include the following: (Select ALL that apply.)
A. GI upset, nausea
C. Insomnia, akathisia
D. Weight gain
E. Hair loss, thinning
A, D, E.
A patient is taking birth control pills for contraception. She requires an anticonvulsant. Which agent would not lower the efficacy of her contraceptive method?
E. All the agents listed except levetiracetam are enzyme inducers and should not be used with oral contraceptives (and many other medications). If she does require one of these anticonvulsants, she will risk pregnancy if she uses this method of birth control.
Choose the correct statement concerning carbamazepine therapy:
A. Carbamazepine formulations include tablets, capsules, and an injection.
B. The therapeutic range is 50-100 mcg/mL
C. The drug has a boxed warning for renal failure.
D. Carbamazepine is a potent inducer and will lower the concentration of many other drugs.
E. Carbamazepine has less drug interactions than oxcarbazepine.
D. Carbamazepine (Carbatrol, Epitol, Equetro, Tegretol, Tegretol-XR) is a potent inducer of many CYP 450 enzymes, including 3A4. Carbamazepine is available as tablets, capsules, and an oral suspension.
Choose the statement below that best describes the following anticonvulsants: carbamazepine, oxcarbazepine, phenytoin, phenobarbital & primidone:
A. These anticonvulsants are enzyme inducers and can lower the concentration of other drugs
B. These anticonvulsants are enzyme inhibitors and can raise the concentration of other drugs.
C. Carbamazepine is an auto-inhibitor.
D. These anticonvulsants do not affect the CYP 450 system.
E. These anticonvulsants are enzyme inhibitors and can lower the concentration of other drugs.
A. These anticonvulsants induce many of the CYP 450 isoenzymes, including CYP 450 3A4 (half of the drugs subject to hepatic metabolism are metabolized by 3A4). Therefore, they lower the concentration of many other drugs.
A child with epilepsy presents with a new prescription for Lamictal 250 mg BID #60. Choose the correct statements: (SelectALL that apply.)
A. The patient should be counseled on the risk of serious rash.
B. The prescription cannot be filled until the prescriber is contacted to correct the dose.
C. The generic name is zonisamide.
D. Lamotrigine concentration will be markedly increased if the patient is taking valproate.
E. Lamotrigine is never appropriate to use in a child.
A, B, D. The risk of severe, potentially life-threatening rash from lamotrigine (Lamictal) therapy may be increased by co-administration with valproate, exceeding the recommended initial dose, or increasing the dose too rapidly. Lamotrigine is started at 25 mg daily for the first 2 weeks, unless the patient is on an inhibitor, in which case the lower dosing in the package insert can be referenced.
A child with epilepsy presents with a new prescription for Keppra 250 mg BID #60. Which of the following is an appropriate generic substitution for Keppra?
B. The generic name of Keppra is levetiracetam.
Which of the following are boxed warnings for valproate and divalproex? (Select ALL that apply.)
A. Pulmonary fibrosis
B. Stevens-Johnson Syndrome, Toxic Epidermal Necrolysis
D. Hepatic failure
C, D, E.
Jasmine has been taking primidone for many years. Primidone is similar in the side effect profile to this drug:
C. Primidone is a pro-drug of phenobarbital and causes lethargy, drowsiness and dizziness.
Which of the following anticonvulsants is contraindicated in a sulfa allergy?
E. Zonisamide (Zonegran) is contraindicated with a sulfa allergy.
A pediatric patient with partial onset seizures has several other medical conditions and is taking an assortment of prescription medications. The physician has begun the child on levetiracetam. Choose the correct statement:
A. Levetiracetam has a high risk of drug interactions and may pose a problem with the child's other medications.
B. The brand name of levetiracetam is Trileptal.
C. Levetiracetam may cause somnolence, hostility, nervousness and asthenia.
D. Levetiracetam is not indicated for partial seizures.
E. Levetiracetam is not approved in patients less than 18 years of age.
C. A lack of significant drug interactions makes levetiracetam an attractive agent. It is considered one of the first-line agents for partial and generalized, tonic-clonic seizures.
Which statements concerning status epilepticus are accurate? (Select ALL that apply.)
A. This condition is a medical emergency; it only takes about 5 minutes of seizure activity to destroy neurons and this type of seizure can last much longer.
B. Status epilepticus can mean that a patient has had two or more seizures without a complete recovery of consciousness between the episodes.
C. Patients in status epilepticus should be rolled on their side.
D. You should put something in the patient's mouth so they do not swallow their tongue.
E. The first line agents for treating status epilepticus are lorazepam or diazepam.
A, B, C, E. In some patients status epilepticus is fatal. This is a medical emergency. In children with epilepsy, 20% will have an episode of status epilepticus within five years of diagnosis. Five percent of children with febrile seizures present with status epilepticus.
Select the correct statements concerning phenytoin: (Select ALL that apply.)
A. The therapeutic range is 10-20 mcg/mL
B. Check the albumin level when checking the phenytoin level.
C. Only mix in normal saline.
D. Never administer faster than 50 mg/minute.
E. Avoid intramuscular injections.
A, B, C, D, E.
A pharmacist will counsel a patient on the possible side effects of oxcarbazepine. The most likely side effects from the use of oxcarbazepine are:
A. Loss of appetite, weight loss, anorexia
B. Erectile dysfunction, decreased libido
C. Alopecia, glossitis
D. Sleepiness, ataxia, diplopia
EI. nsomnia, agitation, restlessness
D. Anticonvulsants commonly cause these CNS side effects: somnolence (sleepiness), dizziness, ataxia, diplopia, confusion and fatigue. A few anticonvulsants cause loss of appetite, but not oxcarbazepine. If a rash occurred with carbamazepine, there is risk with oxcarbazapine.
Which of the following drugs are known to increase seizure risk? (Select ALL that apply.).
A, B, D, E. With most drug interactions, the risk is dose-related. If kept at reasonable doses (such as not exceeding 450 mg/day of bupropion), the risk can be minimized. With meperidine, the metabolite normeperidine is increasing the risk.
Ethosuximide (Zarontin) is primarily used for this type of seizure:
A. Generalized seizures
B. Partial seizures
C. Complex partial seizures
D. Absence seizures
E. Status epilepticus
D. Ethosuximide is indicated for the control of absence (petit mal) seizures.
A young woman has been using Topamax for migraine prophylaxis. She may be interested to know that the FDA has issued a warning regarding the risk for this type of birth defect in children born to women taking Topamax during pregnancy. The warning concerned the following birth defect:
A. Shortened stature
B. Mental retardation
C. Spina bifida
D. Tetralogy of Fallot
E. Cleft lip and/or palate
E. There is a risk of cleft lip and/or cleft palate in newborns whose mothers took Topamax during pregnancy. Topamax was pregnancy category C, but was changed to category D due to increased awareness of risks to the child.
Which of the following anticonvulsants are associated with oligohydrosis? (Select ALL that apply.)
A. Valproic acid
B, C. Both topiramate and zonisamide cause oligohydrosis (decreased sweating). Oligohydrosis primarily affects children.
Carbamazepine, phenytoin, valproate/divalproex and clonazepam are FDA Pregnancy Category D. Choose the correct definition for the meaning of this pregnancy risk category:
A. Use of these agents is contraindicated in pregnancy and should not be used.
B. Use of these agents can be considered safe during the 1st trimester only; do not use after the 1st trimester.
C. Use of these agents can be considered safe during the 3rd trimester only; therefore, do not use these medications during the 1st and 2nd trimesters.
D. These agents have known fetal risk; the benefit must outweigh the risk and the use of safer drugs is not possible.
E. Use of these agents can be considered safe at any time.
D. The 1st trimester of pregnancy (when organs develop) is the most dangerous time for drug-induced fetal damage; if possible, prescription agents should be avoided during this time. If prescription drugs are required at any time during pregnancy, the drugs are chosen based on the FDA categories. These range from Pregnancy Category A (safest) to Pregnancy Category X (contraindicated).
A female patient has been taking phenytoin 100 mg TID for two months. It was reported that she had "two or three" seizures during this time. The phenytoin level was taken 4 weeks ago and was 14.8 mcg/mL, with an albumin level of 4.5 g/dL. The patient went to the physician last week complaining of a recent "bad epileptic fit" and "having to pee all the time." She was given a prescription for nitrofurantoin 100 mg BID and the phenytoin dose was kept the same at breakfast and lunch, and doubled to 200 mg with dinner. The patient presented today with symptoms of phenytoin toxicity. What is the most likely cause of the phenytoin toxicity?
A. Nitrofurantoin increased the clearance of phenytoin.
B. Nitrofurantoin inhibits the metabolism of phenytoin.
C. The patient previously had poor phenytoin adherence, which has now improved.
D. Michaelis-Menten kinetics
E. None of the above.
D. Phenytoin has saturable or Michaelis-Menten kinetics. The level can increase more than would be expected after a dose increase. The higher the phenytoin level, the more likely a seemingly reasonable increment in daily dosage may turn out to be a prescription for toxicity.
A hospital pharmacist is serving on the P&T committee. She is considering the addition of fosphenytoin to the formulary. Choose the correct statement concerning fosphenytoin:
A. Phenytoin is the pro-drug of fosphenytoin.
B. Fosphenytoin causes less hypotension than phenytoin.
C. Fosphenytoin is reconstituted in saline solution only.
D. Fosphenytoin cannot be given by intramuscular injection.
E. Fosphenytoin is available in oral tablets, solution and injection.
B. Fosphenytoin (Cerebyx) is a pro-drug of phenytoin that comes as an injection. The theoretical advantage to the use of this drug is that seizures can be controlled faster, or at least it can be pushed faster since it causes less hypotension. However, the conversion of fosphenytoin to phenytoin takes time (15-30 minutes) and the seizures are not controlled faster. An advantage to fosphenytoin is that it can be given IM, and it can be mixed with either NS or D5W.
Choose the correct trade-generic match:
C. The generic name of Gabitril is tiagabine.
Felbamate (Felbatol) has the following boxed warnings: (Select ALL that apply.)
A. Renal failure
B. Hepatic failure
C. Aplastic anemia
B, C. Acute liver failure is associated with the use of felbamate. The second boxed warning involves a marked increase in aplastic anemia. Due to the risks of aplastic anemia and liver failure, felbamate is considered an anticonvulsant of last-resort.
Which of the following anticonvulsants is indicated for migraine prophylaxis?
A. Topiramate (Topamax) and divalproex (Depakote) are both indicated for migraine prophylaxis. Phenytoin has too many side and adverse effects to be considered for migraine prevention or for other uses besides seizure control.
A mother has brought in a prescription for divalproex sodium for her 6 year-old son who is suffering from seizures. Choose the correct statements concerning divalproex sodium: (Select ALL that apply.)
A. It is not approved for children less than 12 years of age.
B. The brand name is Depakene.
C. The medication comes in delayed-release or sprinkle-filled capsules.
D. The medication may cause liver damage.
E. The initial dose is 2.5 grams twice daily
C, D. Divalproex sodium extended-release is Depakote ER. Valproic acid, or valproate, is Depakene. The initial dose is 125-250 mg BID.
A middle-aged man was in a motor vehicle accident with a head injury and suffered a seizure in the emergency room. He has stabilized, and will be released from the hospital on phenytoin 100 mg TID. Discharge counseling on the use of phenytoin should include a discussion of the following symptom of acute drug toxicity:
A. Gingival hyperplasia
D. Ataxia (lack of coordination, "walking drunk") can occur with toxicity from many drugs, including most anticonvulsants, as well as with excessive alcohol consumption.
A patient is beginning Topamax therapy for epilepsy. He brought in a prescription for Topamax 200 mg BID #60. Which of the following statements is correct?
A. The prescription should not be filled as written.
B. The generic name is lamotrigine.
C. Topamax lowers the risk of glaucoma.
D. Topamax can cause a significant increase in serum bicarbonate.
E. Topamax, unlike other anticonvulsants, can be stopped abruptly if used for seizure control.
A. Topiramate (Topamax) is started at 25 mg BID. It is titrated weekly. The maximum dose is 200 mg BID.
A 34-year old woman with a long history of epilepsy has been using phenobarbital 100 mg TID for many years. She has not had a seizure in the past year. Choose the correct statement:
A. The patient will have developed psychological dependence to phenobarbital.
B. If the phenobarbital were abruptly discontinued, she would have severe physiological withdrawal symptoms and may experience seizures.
C. Phenobarbital is a C III medication.
D. Phenobarbital is a C II medication.
E. She should remain on phenobarbital life-long.
B. Phenobarbital, a C IV barbiturate, will produce tolerance, psychological dependence, and physical dependence (also called physiological dependence) with prolonged use. An abrupt discontinuation would cause the patient to experience physiological withdrawal, including anxiety, tremor, weakness, dizziness, insomnia, orthostasis and the possibility of seizures and delirium. The seizure risk is higher in patients being treated for seizures.
Which of the following agents are associated with modest weight loss? (Select ALL that apply.)
A. Valproic acid
Which of the following statements concerning Dilantin is correct?
A. The drug is safe to administer with tube feeds if the enteral formula is low in sodium.
B. A small increase in dose correlates in a linear fashion with serum levels throughout the dosing range.
C. Serious skin rashes, including SJS and TEN, can occur with the use of this drug.
D. The generic is lamotrigine.
E. It is a strong CYP 3A4 inhibitor.
C. Phenytoin has saturable, or Michaelis-Menten kinetics. Phenytoin is generally separated from tube feedings (two hours before and two hours after) in order to ensure adequate drug availability. This is accurate for all the enteral formulations. Phenytoin is a strong CYP enzyme inducer.
A hospital pharmacist will advise a nurse on a phenytoin injection. The pharmacist should instruct the nurse that phenytoin cannot be injected at a rate faster than:
A. 10 mg/min
B. 25 mg/min
C. 50 mg/min
D. 75 mg/min
E. 150 mg/min
C. The maximum infusion rate is 50 mg/min (usually slower, and much slower in elderly patients). IV phenytoin can cause hypotension and arrhythmias if it is administered too quickly.