Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0033774 (pruritus)
 14,546 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Fosphenytoin is a water-soluble disodium phosphate ester of phenytoin that is converted in plasma to phenytoin. Fosphenytoin is compatible with most common i.v. solutions and can be administered safely through the i.m.route. An additional safety factor is the absence of propylene glycol in the fosphenytoin formulation. Propylene glycol is used as a vehicle in the i.v. phenytoin preparation and by itself may produce serious cardiovascular complications. Studies of the pharmacokinetics, safety, and tolerance of i.v. fosphenytoin have demonstrated that fosphenytoin produces phenytoin plasma concentrations similar to those achieved with oral and i.v. phenytoin, but without significant cardiovascular effects and only minimal discomfort at the injection site. Aside from local reactions, the most common adverse events associated with fosphenytoin have been pruritus and reactions typical of phenytoin (e.g., dizziness, somnolence, and ataxia). Fosphenytoin represents a significant advance in the treatment of patients with seizures who require parenteral therapy.
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PMID:Intravenous administration of fosphenytoin: options for the management of seizures. 864 9

Fosphenytoin sodium, a phosphate ester prodrug of phenytoin, was developed as a replacement for parenteral phenytoin sodium. Unlike phenytoin, fosphenytoin is freely soluble in aqueous solutions, including standard i.v. solutions, and is rapidly absorbed by the i.m. route. Fosphenytoin is metabolized (conversion half-life of 8 to 15 min) to phenytoin by endogenous phosphatases. Therapeutic free (unbound) and total plasma phenytoin concentrations are consistently attained after i.m. or i.v. administration of fosphenytoin loading doses. Fosphenytoin has fewer local adverse effects (e.g., pain, burning, and itching at the injection site) after i.m. or i.v. administration than parenteral phenytoin. Systemic effects related to the CNS are similar for both preparations, but transient paresthesias are more common with fosphenytoin.
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PMID:Pharmacology and pharmacokinetics of fosphenytoin. 864 12

Fosphenytoin is a phosphate ester prodrug of phenytoin developed as a replacement for standard injectable sodium phenytoin. After absorption, phenytoin is cleaved (conversion half-life 8-15 min) from fosphenytoin. Unlike phenytoin, fosphenytoin is freely soluble in aqueous solutions (including standard intravenous solutions) and rapidly absorbed by the intramuscular route. Fosphenytoin has been tested successfully for three indications in humans: intramuscular maintenance dosing, intramuscular loading dose administration, and intravenous treatment of status epilepticus. Local toxicity (pain, burning, itching) is less by the intramuscular or intravenous route for fosphenytoin than for standard injectable sodium phenytoin. Systemic toxicity is similar with both preparations except that hypotension is less common and paresthesias are more common with fosphenytoin.
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PMID:Fosphenytoin (Cerebyx). 903 68

Fosphenytoin is a phenytoin prodrug that has been introduced to overcome some of the problems and limitations associated with parenteral phenytoin sodium administration. Fosphenytoin is a phosphate ester prodrug that is converted to phenytoin in vivo by peripheral esterases. Fosphenytoin has several advantages and disadvantages that should be considered when selecting its use in place of parenteral phenytoin. Advantages with fosphenytoin include better tolerability, improved safety, better stability, ability for intramuscular administration, and faster infusion rates. Disadvantages with fosphenytoin include rate and dose related paresthesias and pruritus, delayed decreases in blood pressure, the potential for therapeutic drug monitoring errors, and higher drug acquisition costs. In general, given the pros and cons of the new drug, fosphenytoin offers an attractive alternative for parenteral phenytoin in select individuals.
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PMID:Fosphenytoin. 952 55

Fosphenytoin, a prodrug of phenytoin, is rapidly and completely converted to phenytoin in adults after intravenous or intramuscular administration and is significantly better tolerated than parenteral phenytoin. Fosphenytoin is highly plasma-protein bound and, when present in sufficient concentration, will displace phenytoin from plasma proteins. The clinical utility is that fosphenytoin may be used to achieve therapeutic phenytoin concentrations more rapidly than intravenous phenytoin infused at its maximum recommended rate. In a clinical study of generalized convulsive status epilepticus, fosphenytoin, with or without benzodiazepine pretreatment, controlled seizures in 76 (93.8%) of 81 patients. In other studies, fosphenytoin maintained seizure control when substituted for oral phenytoin and for seizure prophylaxis in neurosurgery and trauma patients. Adverse events associated with fosphenytoin generally were related to the central nervous system and were similar to those associated with phenytoin, except for a higher incidence of transient pruritus with fosphenytoin. Intravenous fosphenytoin has significant advantages over intravenous phenytoin: It requires a shorter infusion time and fewer intravenous disruptions, causes less pain and burning at the infusion site and minimal consequences in case of intravenous infiltration, allows longer maintenance of intravenous sites, and has better intravenous fluid compatibility and stability. In contrast to intramuscular phenytoin, intramuscular fosphenytoin is well tolerated in both large loading doses and maintenance doses.
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PMID:Clinical experience with fosphenytoin in adults: pharmacokinetics, safety, and efficacy. 979 47

Fosphenytoin is a phosphate ester prodrug developed as an alternative to intravenous phenytoin for acute treatment of seizures. Advantages include more convenient and rapid intravenous administration, availability for intramuscular injection, and low potential for adverse local reactions at injection sites. Drawbacks include the occurrence of transient paraesthesias and pruritus at rapid infusion rates, and cost. Fosphenytoin is highly bound (93-98%) to plasma proteins. Saturable binding at higher plasma concentrations accounts for an increase in its distribution volume and clearance with increasing dose and infusion rate. Fosphenytoin is entirely eliminated through metabolism to phenytoin by blood and tissue phosphatases. The bioavailability of the derived phenytoin relative to intravenous phenytoin is approximately 100% following intravenous or intramuscular administration. The half-life for conversion of fosphenytoin to phenytoin ranges from 7-15 minutes. Faster intravenous infusion rates and competitive displacement of derived phenytoin from plasma protein binding sites by fosphenytoin compensate for the expected conversion-related delay in appearance of phenytoin in the plasma. Unbound phenytoin plasma concentrations achieved with intravenous fosphenytoin loading doses of 100-150 or 50-100mg phenytoin sodium equivalents/min are comparable, and achieved at similar times, to those with equimolar doses of intravenous phenytoin at 50 (maximum recommended rate) or 20-40 mg/min, respectively. The rapid achievement of effective concentrations permits the use of fosphenytoin in emergency situations, such as status epilepticus. Following intramuscular administration, therapeutic phenytoin plasma concentrations are observed within 30 minutes and maximum plasma concentrations occur at approximately 30 minutes for fosphenytoin and at 2-4 hours for derived phenytoin. Plasma concentration profiles for fosphenytoin and total and unbound phenytoin in infants and children closely approximate those in adults following intravenous or intramuscular fosphenytoin at comparable doses and infusion rates. Earlier and higher unbound phenytoin plasma concentrations, and thus an increase in systemic adverse effects, may occur following intravenous fosphenytoin loading doses in patients with a decreased ability to bind fosphenytoin and phenytoin (renal or hepatic disease, hypoalbuminaemia, the elderly). Close monitoring and reduction in the infusion rate by 25-50% are recommended when intravenous loading doses of fosphenytoin are administered in these patients. The potential exists for clinically significant interactions when fosphenytoin is coadministered with other highly protein bound drugs. The pharmacokinetic properties of fosphenytoin permit the drug to serve as a well tolerated and effective alternative to parenteral phenytoin in the emergency and non-emergency management of acute seizures in children and adults.
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PMID:Fosphenytoin: clinical pharmacokinetics and comparative advantages in the acute treatment of seizures. 1248 78

Fosphenytoin, a water-soluble prodrug of the antiepileptic drug phenytoin, is entirely and rapidly converted to this antiepileptic drug. The mechanism of action of fosphenytoin is related to the blockade of voltage-operated sodium channels. It was developed in order to obtain a phenytoin-like drug with improved water solubility. Its maximal plasma concentration is achieved within 90-190 min following intramuscular administration with bioavailability being complete after intravenous injection. The main indications for fosphenytoin are the treatment of convulsive status epilepticus and the prevention/management of seizures during neurosurgery. Adverse effects of fosphenytoin may include: cardiovascular events (hypotension, arrhythmias), paresthesias or pruritus or some central events - somnolence, headache, dizziness, nystagmus and ataxia. The incidence of purple glove syndrome (edema, discoloration and pain distal to the site of intravenous administration) is less frequent than after phenytoin. Generally, the development of fosphenytoin aimed at avoiding complications associated with parenteral use of phenytoin.
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PMID:The safety and efficacy of fosphenytoin for the treatment of status epilepticus. 2628 87