Hydantoin group includes -

Ethotoin, fosphenytoin, phenytoin-
Refer Phenytoin Sodium

Drug interactions -summary
Drugs that may increase plasma phenytoin concentrations include-
  
                  Acute alcohol intake
                  Amiodarone
                  Chloramphenicol
                  Chlodiazepoxide
                  Cimetidine
                  Diazepam
                  Dicoumarol
                  Disulfram
                  Estrogens
                  Ethosuximide
                  Fluoxetine
                  H-2 antagonists
                  Halothane
                  Isoniazid
                  Methylphenidate
                  Phenoxythiazine
                  Phenylbutazone
                  Salicylates
                  Succinimides
                  Sulphonamides
                  Tolbutamide
                  Trazadone

Drugs that may decrease plasma concentrations-
        
                   Carbamazepine
                   Chronic alcohol abuse
                   Reserpine

Drugs that may increase or decrease plasma phenytoin cooncentrations-

                   Phenobarbital
                   Valproic acid
                   Sodium valproate

TCAs may precipitate seizures in suseptible patients and fosphenytoin dosage may need to be  adjusted

Drugs whose efficacy is impaired by phenytoin include-

                    Anticoagulants
                    Corticosteroids
                    Coumarin
                    Digitoxin
                    Doxyxycline
                    Estrogens
                    Furosemide
                    Contraceptives Oral
                    Rifampin
                    Quinidine
                    Theophylline
                    Vitamin D
                      
                    

Epilepsy

ANTICONVULSANTS  INCLUDE -

BARBITURATES -                         OXAZOLIDINEDIONES-              MISCELLANEOUS-
Phenobarbitone                             Paramethadione                          Lamotrigine
                                                        Trimethadione                              Primidone
HYDANTOINS-                                                                                     Valproic acid
Phenytoin                                        BENZODIAPINES-                      Cabamazepine
Mephenytoin                                   Clonazepam                                Phenacemide
Ethotoin                                           Clorazepate                                 Felbamate
                                                         Diazepam                                    Gabapentin
SUCCINIMIDES-
Ethosuximide
Methsuximide
Phensuximide

REFER PHENYTOIN SODIUM -

Hydantoin group includes -

Ethotoin, fosphenytoin, phenytoin-

Refer Phenytoin Sodium
 

Cardiovascular-
Hypotension ( 8% IV ), tachycardia (2.%  IV ), Vasodilation ( 6%  IV )

CNS-
Agitation ( 3% IV  ) ataxia ( 11% IV, 8.% IM ),brain edema ( 2.% ) ,

CNS depression (  1%)dizziness ( 31% IV, 5% IM ), dysarthria ( 2 % IV ), 

extrapyramidal symptoms ( 4.% IV ),headache ( 2.% IV , 9% IM ),

hypesthesia ( 2% IV ) incordination ( 4% IV, 8% IM ),

insomnia  (  1% ), mental  confusion (  1% ),

 motor twitching ( 1% )nystagmus ( 44% IV, 15% IM ),

paresthesia ( 4.% IV , 4% IM ), reflux decreased (3% IM ) 

somnolence ( 20% IV, 6.7% IM ), stupor ( 7.7% IV )

tremor ( 3.% IV , 9% IM ), vertigo ( 2% IV )

Dermatologic -

Pruritus ( 49% IV, 3% IM ), skin rash ( > 1% )

GI -
Constipation ( > 1% ), diarrhea ( 1% ) dry mouth ( 4% IV )
ecchymosis ( 7% IM ), nausea ( 9% IV, 4. % IM ),
tongue disorder (4% IV), vomiting ( 2% IV, 3% IM )

Haematological/ lymphatic -
Leukopenia ( 1% ), lymhadenopathy (  1% )
thrombocytopenia (  1% )

Hypersensitivity -
Local -  inflammation ( 1% ), tenderness (  1% )

Special senses -
Amblyopia (2%  IV ), deafness (2%  IV ) diplopia (3%  IV )
taste perversion (3%  IV ), tinnitus ( 9 %  IV )

Miscellaneous -
Accidental injury (3%  IV ), asthenia  (2% , 4%  IM ), back pain ( 2%  IV )
fever ( >1%  ), pelvic pain ( 4% IV )

Hypersensitivity to fosphenytoin or its ingredients or phenutoin or other hydantoins, sinus bradycardia,  sino-atrial block, second and third degree AV block, and Adams-Stokes syndrome

Special precautions-

As with other antileptics drugs, abrupt withdrawal may increase seizure frequency

Discontinue if skin rash or signs of an allergic or hypersensitivity reaction appear
( including lymphadenopathy or hepatotoxicity )

Acute confusion states may occur if plasma phenytoin concentrations are excessive

Patients with renal and hepatic impairment may be prone to increase in the frequency and severity of adverse effects.

May raise blood glucose in diabetic patients

Indication-

Epilepsy

Dosage-

1.5mg of fosphenytoin sodium equivalent to 1mg PE- Fosphytoin is always prescribed in PE units.
Status Epilepticus-
Loading dose- 15mg PE/kg by IV infusion at 100 to max 150mg PE/min
Maintenance- 4 to 6mg PE/kg/day by IV infusion (50 to 100mg PE/min) or IM injection adjusted according to patient response and trough plasma injection concentrations.
Transfer to oral when appropiate

 REFER PHENYTOIN SODIUM -

Pharmacology-

Following parentral administration, fosphenytoin is converted to phenutoin. Being a prodrug of
 phenytoin, anticonvulsant activities of fosphenytoin are attributable to phenytoin.

Pharmacokinetics-
Fosphenytoin is completely converted to phenytoin following both IV and IM administration.
 The conversion half-life of fosphenytoin to phenytoin is approximately 15 minutes.

 Phenytoin derived  from administration of fosphenytoin is extensively metabolised in the liver and  excreted in urine primarily as 5-(p-hydrooxy-phenyl)-5- phenmylhydantoin  and its glucoronide,  little unchanged phenytoin ( 1 to 5% of the fosphenytoin dose ) is recoverd in urine.