Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0012833 (dizziness)
 9,689 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The US Food and Drug Administration (FDA) has not approved any injectable contraceptives, but, in December 1990, it approved Norplant, an implantable contraceptive. Family planning providers insert 6 capsules, each with 36 mg levonorgestrel, in a fan shape under the dermis of the upper arm. Norplant protects against pregnancy for at least 5 years . Fecundity returns within 2 weeks after capsules' removal. The steady low levels of levonorgestrel keep down both luteinizing hormone and follicle stimulating hormone levels. It suppresses ovulation and thickens the cervical mucus. Contraindications of Norplant are active thromboembolism, undiagnosed genital bleeding, acute liver disease, liver tumors, and breast cancer. Phenytoin and other drugs which speed up liver metabolism reduce Norplant's efficacy. The leading side effect of Norplant is irregular bleeding patterns. Some less common side effects include headaches, nervousness, dizziness, and acne. First year continuation rates range from 76 to 99% and 25 to 78% for 5 years of use. More than 85% of Norplant users are satisfied. Both continuation and satisfaction are associated with patient counseling. Research and development of biodegradable and other nonbiodegradable implants is ongoing. The most common injectable contraceptive in the world is Depo-Provera. 150 mg of Depo-Provera every 3 months suppresses ovulation, deteriorates the endometrium, thickens cervical mucus, and reduces motility of the tubes, thereby providing adequate protection against pregnancy. Some research shows Depo-Provera use significantly increases the low-density lipoprotein to high-density lipoprotein ratio, thereby increasing the risk for atherogenesis. Effectiveness rates match those of Norplant. Norethindrone enanthate was the first injectable contraceptive. Even though 40 countries approve it, the US does not. Animal studies of injectable microspheres or microcapsules with either progestogen or progestogen and estrogen are in progress.
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PMID:Injectable and implantable contraceptives. 138 11

We conducted a 10-center, double-blind trial to compare the efficacy and toxicity of four antiepileptic drugs in the treatment of partial and secondarily generalized tonic-clonic seizures in 622 adults. Patients were randomly assigned to treatment with carbamazepine, phenobarbital, phenytoin, or primidone and were followed for two years or until the drug failed to control seizures or caused unacceptable side effects. Overall treatment success was highest with carbamazepine or phenytoin, intermediate with phenobarbital, and lowest with primidone (P less than 0.002). Differences in failure rates of the drugs were explained primarily by the fact that primidone caused more intolerable acute toxic effects, such as nausea, vomiting, dizziness, and sedation. Decreased libido and impotence were more common in patients given primidone. Phenytoin caused more dysmorphic effects and hypersensitivity. Control of tonic-clonic seizures did not differ significantly with the various drugs. Carbamazepine provided complete control of partial seizures more often than primidone or phenobarbital (P less than 0.03). Overall, carbamazepine and phenytoin are recommended drugs of first choice for single-drug therapy of adults with partial or generalized tonic-clonic seizures or with both.
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PMID:Comparison of carbamazepine, phenobarbital, phenytoin, and primidone in partial and secondarily generalized tonic-clonic seizures. 392 35

Phenytoin sodium was evaluated for its effect on the development and intensity of acute mountain sickness (AMS) because of its ability to reduce intracellular Na+ concentrations in brain and thereby minimize any tendency to increase cellular volume, a hypothetical cause of AMS. Six men aged 19-35 were exposed to approximately 4600 m altitude in a hypobaric chamber for 52 h on two occasions separated by 10 d at sea level. Subjects received wither phenytoin or placebo for 18 h before (700 mg, divided dose) and throughout (100 mg t.i.d.) each altitude exposure in a double-blind, repeated-measures (crossover) design. Phenytoin serum concentrations ranged from 4.4-13.9 micrograms/ml during altitude exposure. Twice daily questionnaires and clinical evaluations showed no marked benefit from phenytoin on the occurrence, severity, or duration of AMS symptoms: headache, nausea, insomnia, and general malaise. Overall, 1 subject felt better, 2 felt worse, 1 felt the same; 2 were not suitably comparable. There was no observed relationship between serum levels and symptoms of AMS. Moderate degrees of weakness and dizziness were each reported by 3 subjects with phenytoin but not with placebo, however. Resting pulmonary ventilation, end-tidal PO2 and PCO2, map reading abilities and respiratory mask donning times were not affected by phenytoin. Under the conditions of this trial, phenytoin did not appear to be useful in managing AMS.
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PMID:Phenytoin: ineffective against acute mountain sickness. 676 69

Phenytoin is a commonly prescribed antiepileptic drug. Due to its saturation (zero-order) pharmacokinetics, phenytoin carries a special risk of dose-related toxicity that is an important issue in emergency medicine. The purpose of this cross-sectional case-series study was to investigate the causes, symptoms, misdiagnoses, and outcomes of acute phenytoin intoxication. It was based on a retrospective chart review of 30 inpatients (mean age, 41.6 +/- 22.8 years) with 36 episodes of acute phenytoin intoxication at our university hospital in the past 13 years. The average initial serum phenytoin level was 47.3 +/- 9.7 microg/mL (range, 27.9-70.4 microg/mL). Excessive self-medication, misunderstanding of the prescription order, and probable drug interaction were the three leading causes of acute phenytoin intoxication. Unsteady gait, dizziness/vertigo, nausea/vomiting, general weakness, and drowsiness were the most common presenting symptoms. The tentative diagnostic accuracy was 67%. The most common initial misdiagnosis was brainstem or cerebellum stroke (14%). The clinical course in all patients was uneventful under temporary withdrawal of phenytoin and supportive care. We concluded that acute phenytoin intoxication was relatively under-diagnosed in the emergency service. Although acute phenytoin intoxication causes no mortality and has a good outcome, the unsteady gait increases the risk of injuries caused by falls. The management of acute phenytoin intoxication includes temporary withdrawal of phenytoin and supportive care.
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PMID:Acute phenytoin intoxication: causes, symptoms, misdiagnoses, and outcomes. 1569 87

Older generation antiepileptic drugs like Phenobarbital (Luminal), carbamazepine (Tegretol), phenytoin (Dilantin), and valproic acid (Depakote) have several shortcomings such as suboptimal response rates, significant adverse effects, several drug interactions, and a narrow therapeutic index. New antiepileptic drugs have been developed in the last decade to overcome some of these problems. These newer generation antiepileptics like felbamate (Felbatol), gabapentin (Neurontin), lamotrigine (Lamictal), levetiracetam (Keppra), oxcarbazepine (Trileptal), tiagabine (Gabitril), topiramate (Topamax), and zonisamide (Zonegran) have better tolerability profiles, low interaction potential, and significantly less enzyme inducing or inhibiting properties. As the use of antiepileptic drugs has expanded to include treatment of neuropathic pain, newer side effects have been reported. In addition to the common side effects of antiepileptic drugs, like dizziness, drowsiness, and mental slowing; other side effects like weight gain, metabolic acidosis, nephrolithiasis, angle closure glaucoma, skin rash, hepatotoxicity, colitis, and movement and behavioral disorders, to name a few, have been brought to our attention. This review is an attempt to highlight the features and incidences of some of these side effects.
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PMID:Side effects of antiepileptics--a review. 1717 1

A 58-year-old female receiving gemcitabine and cisplatin chemotherapy for stage IV gallbladder cancer developed the clinicoradiologic syndrome, posterior reversible encephalopathy syndrome (PRES). Just before the 4th gemcitabine chemotherapy cycle, she was admitted to the hospital with complaints of headache, dizziness, and generalized tonic-clonic seizures. A MRI was performed on the day when the seizure developed, and the findings showed patchy cortical and subcortical T2 hyperintensity without enhancement that involved both occipital and parietal lobes. Phenytoin loading and maintenance was started for prevention of recurrent seizures, which was successful. The follow-up brain MRI obtained 10 days after the seizure attack showed completely resolved radiologic findings. After the MRI findings revealed complete resolution, phenytoin maintenance was stopped. Even with discontinuation of phenytoin, she had no seizures or other clinical manifestations.
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PMID:A case of gemcitabine and cisplatin associated posterior reversible encephalopathy syndrome. 1968 73