Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0018681 (headache)
 56,091 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The hypothesis was tested that an acute oxidation deficiency related to potential dietary trigger factors plays a role in the migraine attack. Migraine sufferers (14F and 4M), fulfilling the criteria for migraine with and without aura according to the classification of the International Headache Society, were coadministered oral mephenytoin (100 mg) and debrisoquine (10 mg) during the initial phase of a typical migraine attack. This was repeated during a period without migraine. The hydroxylation of mephenytoin and debrisoquine hydroxylation did not differ during and without the migraine attack. We conclude that hydroxylation, via cytochrome P-450 (2D6, 2C8 and 9), is not reduced during the migraine attack. The results do not support the hypothesis that oxidation deficiency is involved in the pathophysiology of migraine.
Cephalalgia 1992 Jun
PMID:Cytochrome P-450-dependent hydroxylation in migraine. 162 10

Hypertensive patients, particularly the elderly, may often suffer from other diseases. Therefore, antihypertensive compounds should not negatively affect such disorders. Felodipine is a calcium antagonist that has potentially beneficial effects in angina pectoris and congestive heart failure. Further, it does not adversely affect lung function in asthmatic patients or glucose tolerance in patients with diabetes. Preliminary investigations also indicate that felodipine has no negative influence on plasma lipid levels. Although felodipine seems to be safe in most patients, treatment with felodipine should at present be avoided in pregnant women, since digital anomalies have been observed in rabbit fetuses. The adverse effects seen during treatment with felodipine are usually mild and transient and generally related to the vasodilatory action of the drug, the most common being ankle edema, headache, flushing, dizziness, and palpitations. The only significant drug interactions with felodipine occur with inducers and inhibitors of the cytochrome P-450 system, which is responsible for the metabolism of felodipine.
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PMID:The safety of felodipine. 169 36

The H2-receptor antagonists cimetidine, ranitidine, and famotidine are well tolerated, with a low frequency and similar spectrum of adverse effects. The occasional problematic effects that have been associated with these agents include central nervous system symptoms (mental confusion, headache, and depression), rare cases of thrombocytopenia, and cardiovascular events related to the rate of intravenous infusion. Severe renal and hepatic impairment appear to be associated with a higher occurrence of central nervous system effects. Because the H2-receptor antagonists elevate gastric pH, bind to and inhibit the hepatic cytochrome P-450 enzyme system, and undergo renal tubular secretion, competition with other drugs sharing these pathways has resulted in a number of drug interactions, most of which are not clinically significant. The interaction that occurs with theophylline and warfarin when the cytochrome P-450 enzyme system is inhibited by cimetidine and ranitidine requires monitoring. Recent data suggest that administering cimetidine 800 mg at bedtime has less effect on the serum concentrations of warfarin and theophylline than other dosing regimens. Evidence to date indicates that famotidine does not bind to cytochrome P-450 to a significant extent, and interactions with drugs metabolized by this system have not been reported; however, clinical experience with this agent is very limited.
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PMID:Clinically important adverse effects and drug interactions with H2-receptor antagonists: an update. 289 55

The H2-receptor antagonists which are used for ulcer therapy fall into four main structural classes. Cimetidine is an imidazole derivative; ranitidine belongs to the basically substituted furans, famotidine is a member of the guanidinothiazole group; and roxatidine belongs to the aminoalkylphenoxy series. Famotidine is the most potent, selective H2-receptor antagonist yet available for ulcer therapy. On a weight basis, famotidine is approximately eight times more potent than ranitidine and 40 times more potent than cimetidine. Cimetidine, ranitidine and famotidine are competitive antagonists, while the long-acting H2-receptor antagonists, e.g. loxtidine and lamitidine, are insurmountable H2-receptor blockers. Famotidine has a longer duration of action than either ranitidine or cimetidine. Because famotidine does not interact with cytochrome P-450 of the hepatic enzyme system, it does not appear to affect the metabolism of drugs metabolized by this system. The overall number of side-effects of the H2-receptor antagonists is in the range of 2-3% and no irreversible adverse effects are known. Famotidine has been found to be generally well tolerated. In a first post-marketing study, the number of patients with side-effects was only 0.43%. Side-effects such as headache, dizziness, constipation and diarrhoea have been observed only occasionally. Thus, famotidine is a safe and potent H2-receptor blocker of acid secretion.
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PMID:What are the differences between the H2-receptor antagonists? 290 67

Tropisetron is a novel, potent and highly selective 5-HT3 receptor antagonist, which is active in the treatment of nausea and vomiting induced by highly emetogenic chemotherapeutic drugs such as cisplatin. Tropisetron selectively blocks the excitation of the presynaptic 5-HT receptors of the peripheral neurones involved in the emetic reflex, and may have other direct actions in the CNS on 5-HT3 receptors, mediating the actions of vagal inputs to the area postrema. Toxicological studies show that tropisetron is generally well tolerated by all animal species investigated and no specific organ toxicity was observed, other than slight loss of body weight development. In man, tropisetron metabolism is linked to the cytochrome P-450 2D6 isoenzyme system, which determines the polymorphism of debrisoquine/sparteine metabolism. As a result, there are phenotypical populations of extensive and poor metabolizers. The two main adverse events in human volunteer tolerability studies with tropisetron were headache and constipation. These adverse events tended to be slightly more intense and to last longer in poor metabolizers, compared with extensive metabolizers. Tropisetron had similar pharmacokinetic characteristics in elderly patients and renal patients, compared with healthy subjects. From a toxicological and pharmacokinetic point of view, therefore, daily doses of 5 mg tropisetron can be administered to both poor and extensive metabolizers, as well as to special populations, without any particular precautions.
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PMID:Pharmacology, toxicology and human pharmacokinetics of tropisetron. 836 93

1. Dapsone is a potent anti-inflammatory and anti-parasitic compound, which is metabolised by cytochrome P-450 to hydroxylamines, which in turn cause methaemoglobinaemia and haemolysis. However, during the process of methaemoglobin formation, erythrocytes are capable of detoxifying the hydroxylamine to the parent drug, which may either reach the tissues to exert a therapeutic effect or return to the liver and be re-oxidised in a form of systemic cycling. This glutathione-dependent effect, combined with the un-ionised state of the drug at physiological pH, may contribute to its efficacy. 2. Paradoxically, other aspects of the glutathione-dependent cycling of the hydroxylamine metabolite may contribute to the major adverse reaction of the drug, agranulocytosis. Erythrocytes exposed to the metabolite and repeatedly washed may still release the hydroxylamine in sufficient concentration to kill mononuclear leucocytes in vitro. Thus, erythrocytes may be a conduit for the hydroxylamine to reach the bone marrow to covalently bind to granulocyte precursors, which may trigger an immune response in certain individuals and may lead to the potentially fatal eradication of granulocytes from the circulation. 3. Attempts to increase patient tolerance to dapsone have been most successful using a metabolic inhibitor to reduce hepatic oxidation of the drug to the hydroxylamine. Methaemoglobin formation in the presence of cimetidine was maintained at 30% below control levels for almost 3 mo, and patients' reported side effects such as headache and lethargy were significantly reduced. 4. As clinical application of new and safer dapsone analogues is years away, the use of cimetidine provides an immediate route to increasing patient compliance during dapsone therapy, especially in those maintained on dapsone dosages in excess of 200 mg/day.
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PMID:Dapsone toxicity: some current perspectives. 869 Feb 32

Venlafaxine, a phenylethylamine, and nefazodone, a phenylpiperazine compound, are the newest antidepressants to receive approval of the Food and Drug Administration and to be marketed in the United States. Both strongly inhibit serotonin (5-HT) reuptake; venlafaxine also inhibits norepinephrine reuptake, and nefazodone also exhibits 5-HT2-receptor antagonism. Venlafaxine inhibits the cytochrome P-450 2D6 isozyme to a lesser extent than the selective serotonin reuptake inhibitors (SSRIs) and is 27% protein bound. Structurally, the drugs are unrelated to SSRIs and have some clinically important differences in side effect profiles. Nausea, headache, somnolence, and dry mouth are the most frequently reported side effects with both. Sustained hypertension was reported by a limited number of venlafaxine-treated patients.
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PMID:Venlafaxine and nefazodone, two pharmacologically distinct antidepressants. 916 54

A 44-year-old woman was admitted to the psychiatric unit for exacerbation of her depressive disorder. Blood concentrations of her antidepressant, imipramine, were within normal range and consistent with past concentrations. Her medical history was significant for a chronic headache disorder for which she was given a prescription containing butalbital on admission. The patient's depressive disorder was quickly controlled but relapsed 2 weeks later. Concentrations of imipramine showed a decrease of approximately 50%. Imipramine is metabolized in the liver by the cytochrome P-450 (CYP 1A2) system, and barbiturates are known inducers of this enzyme subset. To our knowledge, an interaction specifically between butalbital and imipramine has not been documented; however, these drugs are extensively prescribed and occasions may arise where they are given concurrently. We recommend repeat measurement of imipramine concentrations 1 week after the start of any butalbital-containing product or barbiturate, and dosage adjustments based on the results and on the patient's response to the change.
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PMID:Possible interaction between imipramine and butalbital. 932 97

Sildenafil is the first orally administered available treatment for erectile dysfunction. It produces a selective vasodilatation of corpus carvernosum, mediated by the inhibition of phosphodiesterase 5, an enzyme that degrades GMPc. Its therapeutic efficacy has been demonstrated in organic as well as psychogenic or mixed erectile dysfunction. Most of its adverse effects, such as headache, flushing, gastroesophageal reflux and color vision disturbances, are related to the mechanism of action. Its interactions with other medications, can have severe adverse consequences. The concomitant use of sildenafil with drugs that release nitric oxide in their molecule, can produce severe hypotension. In patients with coronary heart disease or cardiac failure, this interaction can cause death. Sildenafil is metabolized in the liver through cytochrome P-450. This enzymatic system can be inhibited by cimetidine, ketoconazole or erythromycin. These drugs can increase plasma concentrations of sildenafil. We must identify the groups of patients that will have a better response to the drug and those in whom the drug will be useless. We must also know more about the security profile of the drug. With time, we will know the real role of sildenafil in the treatment of erectile dysfunction.
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PMID:[Sildenafil (viagra) at the time of warnings]. 1034 69

The purpose of this paper is to review the rationale for a new class of nonsteroidal anti-inflammatory drugs (NSAIDs) known as selective cyclooxygenase (COX)-2 inhibitors and to present preliminary clinical data on 2 COX-2 inhibitors that are approved for use in the United States. The primary mechanism of NSAIDs in the treatment of inflammation is the inhibition of COX, which exists in 2 forms. COX-I appears to regulate many normal physiologic functions, and COX-2 mediates the inflammatory response. Theoretically, an NSAID that inhibits COX-2 selectively should decrease inflammation but not influence normal physiologic functions and thus should cause fewer gastrointestinal side effects. Preliminary data suggest that celecoxib, a highly selective COX-2 inhibitor, is superior to placebo and similar to traditional NSAIDs in the short-term treatment of pain due to osteoarthritis, although it has been associated with adverse effects such as headache, change in bowel habits, abdominal discomfort, and dizziness. Celecoxib also has been shown to be as effective as traditional NSAIDs in the treatment of rheumatoid arthritis, but it may cause fewer adverse effects, including endoscopically documented ulcers. Celecoxib is metabolized in the liver by the cytochrome P-450 isozyme CYP2C9, and thus serious drug interactions are possible. In the treatment of osteoarthritis, rofecoxib has been shown to be as effective as traditional NSAIDs and may cause fewer endoscopically documented ulcers, but its complete adverse-effect profile is not known. Until the selective COX-2 inhibitors are widely used and more clinical as well as pharmacoeconomic studies are published, the exact role of COX-2 therapy cannot be determined. words: cyclooxygenase, celecoxib, rofecoxib, rheumatoid arthritis, osteoarthritis.
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PMID:Selective cyclooxygenase-2 inhibitors for the treatment of arthritis. 1046 13


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