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PubMed1986

Effects of deoxycorticosterone-salt hypertension on cell ploidy in the rat aorta.

We investigated the effect of deoxycorticosterone-salt hypertension and its reversal on nuclear ploidy in rat aortic smooth muscle cells, using flow cytometry. Systolic blood pressure and the percentage of cells with tetraploid nuclei increased over a 4-week period and then remained constant. In control rats 6.0 +/- 0.6% of aortic cells had tetraploid nuclei, and this increased to 27.0 +/- 1.1 and 26.6 +/- 2.4% after 4 and 8 weeks of deoxycorticosterone-salt treatment, respectively. Computer analysis of the forward light scatter data obtained from the cell sorter indicated that the average tetraploid cell was approximately 1.6-fold larger than the average diploid cell in both normotensive and hypertensive animals. Analysis of the DNA content of intact cells and isolated nuclei indicated that the increased DNA content per cell was predominantly attributable to tetraploid nuclei rather than binucleated cells. Reversal of hypertension with either a low sodium diet for 8 to 13 weeks or chlorothiazide administration failed to reverse the abnormalities seen in arterial smooth muscle cell ploidy, despite normalization of the blood pressure and the ratio of heart to body weight.

Animals↗
PubMedDate not supplied

Effects of antihypertensive treatment on the cerebral microvasculature of spontaneously hypertensive rats.

Experiments were performed in anesthetized 18-19-week-old spontaneously hypertensive rats (SHR) to evaluate the effects of delayed antihypertensive treatment on cerebrovascular function. Animals were treated for 25 +/- 1 days with an oral antihypertensive regimen consisting of hydralazine, reserpine, and chlorothiazide, resulting in normotension within 2 weeks. Cerebral arterioles were examined via a constantly suffused open cranial window and video microscopy. Resting cerebral blood flow was measured using radioactive microspheres and the reference organ method. While untreated SHR exhibited reductions in arteriolar diameter compared with normotensive Wistar Kyoto rats (WKY), treatment restored arteriolar dimensions to normal. Increments in microvascular wall area, associated with medial hypertrophy in untreated SHR, were completely reversed in treated SHR to a magnitude not different from control. Resting cerebral blood flow was, however, decreased in treated SHR compared with both untreated SHR and WKY; this was due to an increase in total cerebrovascular resistance compared with WKY. Additionally, microvascular pressure in the largest arterioles in treated SHR was reduced compared with both WKY and untreated SHR. There was a significant increase in the relative pressure drop accounted for by the arterial vessels upstream from the cerebral microcirculation in treated SHR. These results suggest that 1) cerebral microvascular abnormalities induced by chronic hypertension are reversed by delayed antihypertensive therapy, and 2) there is a persistent elevation in cerebrovascular resistance upstream from the microcirculation representing large vessel adaptations that may not be readily reversible with treatment.

Animals↗
PubMed1993

Effect of thiazide diuretics against neurally mediated contraction of guinea pig airways. Contribution of carbonic anhydrase.

The effect of thiazide diuretics on neurally and agonist-induced contractile responses of guinea pig airways in vitro were investigated. Tracheal or bronchial strips were suspended in organ baths and isometric tension recorded. Chlorothiazide (CTZ, 10(-4) to 3 x 10(-3) M), hydrochlorothiazide (HCTZ, 10(-3) M), and dichlorphenamide (DCPM, 10(-3) M) significantly potentiated contraction of tracheal strips induced by electrical field stimulation (EFS). They also increased acetylcholine (ACh)- but not carbachol-induced tracheal contraction. In the presence of atropine and propranolol, on the other hand, CTZ and DCPM but not HCTZ significantly inhibited EFS-induced contraction in bronchial strips. We determined whether carbonic anhydrase inhibition could mimic the effects of CTZ and DCPM. Acetazolamide (ATZ), an inhibitor of carbonic anhydrase, had no effect on either EFS- or ACh-induced contraction in tracheal strips but significantly inhibited nonadrenergic, noncholinergic (NANC) contractile responses induced by EFS in bronchial strips. CTZ, DCPM, and ATZ did not affect substance P-induced contractile responses in the bronchi. We conclude that CTZ, DCPM, and ATZ attenuate NANC neurally mediated bronchial contraction by preventing the release of contractile neuropeptides from sensory nerve endings. This effect may occur through inhibition of carbonic anhydrase activity. In addition, thiazide diuretics potentiate contractile responses to ACh in the trachea, probably through inhibition of acetylcholinesterase activity.

Acetylcholine↗
PubMed2001

Hyperinsulinism in short-chain L-3-hydroxyacyl-CoA dehydrogenase deficiency reveals the importance of beta-oxidation in insulin secretion.

A female infant of nonconsanguineous Indian parents presented at 4 months with a hypoglycemic convulsion. Further episodes of hypoketotic hypoglycemia were associated with inappropriately elevated plasma insulin concentrations. However, unlike other children with hyperinsulinism, this patient had a persistently elevated blood spot hydroxybutyrylcarnitine concentration when fed, as well as when fasted. Measurement of the activity of L-3-hydroxyacyl-CoA dehydrogenase in cultured skin fibroblasts with acetoacetyl-CoA substrate showed reduced activity. In fibroblast mitochondria, the activity was less than 5% that of controls. Sequencing of the short-chain L-3-hydroxyacyl-CoA dehydrogenase (SCHAD) genomic DNA from the fibroblasts showed a homozygous mutation (C773T) changing proline to leucine at amino acid 258. Analysis of blood from the parents showed they were heterozygous for this mutation. Western blot studies showed undetectable levels of immunoreactive SCHAD protein in the child's fibroblasts. Expression studies showed that the P258L enzyme had no catalytic activity. We conclude that C773T is a disease-causing SCHAD mutation. This is the first defect in fatty acid beta-oxidation that has been associated with hyperinsulinism and raises interesting questions about the ways in which changes in fatty acid and ketone body metabolism modulate insulin secretion by the beta cell. The patient's hyperinsulinism was easily controlled with diazoxide and chlorothiazide.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1983

Indapamide: a unique diuretic?

Indapamide (Lozol) is a new diuretic and antihypertensive agent. The drug appears to have a unique mechanism of action, combining diuretic effects with a direct vascular action, presumably secondary to calcium channel blockade. Available studies indicate that indapamide is comparable to hydrochlorothiazide, chlorothiazide, furosemide, and other diuretic agents in the management of hypertension and edema. The drug produces toxicity similar to that of the thiazide and loop diuretics; however, it does not appear to increase cholesterol levels. Although it is claimed that indapamide produces no effect on glucose levels, hyperglycemia has been reported. Indapamide is safe and effective for treatment of hypertension in mild to severe renal impairment, but advantages over furosemide are questionable. Indapamide is a unique diuretic, but does not appear to offer advantages over other available agents.

Antihypertensive Agents↗
PubMed2004

Comparison of in vitro models for the prediction of compound absorption across the human intestinal mucosa.

Several in vitro assays have been developed to evaluate the gastrointestinal absorption of compounds. Our aim was to compare 3 of these methods: 1) the bio-mimetic artificial membrane permeability assay (BAMPA) method, which offers a high-throughput, noncellular approach to the measurement of passive transport; 2) the traditional Caco-2 cell assay, the use of which as a high-throughput tool is limited by the long cell differentiation time (21 days); and 3) The BioCoat high-throughput screening Caco-2 Assay System, which reduces Caco-2 cell differentiation to 3 days. The transport of known compounds (such as cephalexin, propranolol, or chlorothiazide) was studied at pH 7.4 and 6.5 in BAMPA and both Caco-2 cell models. Permeability data obtained was correlated to known values of human absorption. Best correlations (r = 0.9) were obtained at pH 6.5 for BAMPA and at pH 7.4 for the Caco-2 cells grown for 21 days. The Caco-2 BioCoat HTS Caco-2 Assay System does not seem to be adequate for the prediction of absorption. The overall results indicate that BAMPA and the 21-day Caco-2 system can be complementary for an accurate prediction of human intestinal absorption.

Biological Assay↗
PubMed1976

Chlorpropamide-induced hyponatremia.

A 29-year-old woman with severe idiopathic diabetes insipidus, while being treated by a combination of chlorpropamide and chlorothiazide, developed the syndrome of inappropriate secretion of ADH (SIADH) following an overdose of chlorpropamide. The syndrome resolved as the serum chlorpropamide level fell. This report demonstrates that a chlorpropamide-induced SIADH can occur in a patient with idiopathic diabetes insipidus, and it appears that the antidiuretic effect of the drug is dose-related.

Adult↗
PubMed1989

Further studies on reductive metabolism of acetohexamide in heart.

Species and sex differences of acetohexamide reductase activity were investigated using the cytosolic fraction of heart homogenate. The activity in the rabbit was considerably higher than that in the other species (guinea pig, hamster, rat and mouse). No sex difference of the activity was observed in any of the species tested. Ketone-containing drugs (daunorubicin, befunolol and levobunolol) other than acetohexamide were little reduced in the cytosol of rabbit heart. Some aldehyde reductase inhibitors (phenobarbital, valproate and chlorothiazide) were found to decrease the acetohexamide reductase activity in the cytosol of rabbit heart.

Acetohexamide↗
PubMed1985

Diuretics. Clinical pharmacology and therapeutic use (Part I).

25 years have elapsed since the introduction of the first effective oral diuretic, chlorothiazide. Diuretics are now amongst the most widely prescribed drugs in clinical practice worldwide. Availability of these drugs has not only brought therapeutic benefit to countless numbers of patients but it has at the same time provided valuable research tools with which to investigate the functional behaviour of the kidney and other electrolyte-transporting tissues. Despite many remaining gaps in our knowledge of the biochemical processes involved in diuretic drug action, available compounds can be divided into 5 groups on the basis of their preferential effects on different segments of the nephron involved in tubular reabsorption of sodium chloride and water. Firstly, there is heterogeneous group of chemicals that share the common property of powerful, short-lived diuretic effects that are complete within 4 to 6 hours. These agents act on the thick ascending limb of Henle's loop and are known as 'high ceiling' or 'loop' diuretics. The second group are the benzothiadiazines and their many related heterocyclic variants, all of which localise their effects to the early portion of the distal tubule. The third group comprises the potassium-sparing diuretics which act exclusively on the Na+-K+/H+ exchange mechanisms in the late distal tubule and cortical collecting duct. The action of drugs in groups 2 and 3 is prolonged to between 12 and 24 hours. The fourth group consists of diuretics that are chemically related to ethacrynic acid but have the unusual property of combining within the same molecule the property of saluresis and uricosuria. These compounds have actions, to different individual extents, in the proximal tubule, thick ascending limb, and early distal tubule and are known as 'polyvalent' diuretics. Finally, there is a mixed group of weak or adjunctive diuretics which includes the vasodilator xanthines such as aminophylline, and the osmotically active compounds such as mannitol. Available evidence on the molecular mechanisms of action of diuretics in each group is reviewed. The haemodynamic, humoral and physical factors involved in control of electrolyte and fluid handling by the kidney in normal conditions and pathological states are discussed in relation to rational choices of different diuretics in the treatment of various oedematous and non-oedematous conditions.

Animals↗
PubMed1985

Diuretics. Clinical pharmacology and therapeutic use (Part II).

25 years have elapsed since the introduction of the first effective oral diuretic, chlorothiazide. Diuretics are now amongst the most widely prescribed drugs in clinical practice worldwide. Availability of these drugs has not only brought therapeutic benefit to countless numbers of patients but it has at the same time provided valuable research tools with which to investigate the functional behaviour of the kidney and other electrolyte-transporting tissues. Despite many remaining gaps in our knowledge of the biochemical processes involved in diuretic drug action, available compounds can be divided into 5 groups on the basis of their preferential effects on different segments of the nephron involved in tubular reabsorption of sodium chloride and water. Firstly, there is a heterogeneous group of chemicals that share the common property of powerful, short-lived diuretic effects that are complete within 4 to 6 hours. These agents act on the thick ascending limb of Henle's loop and are known as 'high ceiling' or 'loop' diuretics. The second group are the benzothiadiazines and their many related heterocyclic variants, all of which localise their effects to the early portion of the distal tubule. The third group comprises the potassium-sparing diuretics which act exclusively on the Na+-K+/H+ exchange mechanisms in the late distal tubule and cortical collecting duct. The action of drugs in groups 2 and 3 is prolonged to between 12 and 24 hours. The fourth group consists of diuretics that are chemically related to ethacrynic acid but have the unusual property of combining within the same molecule the property of saluresis and uricosuria. These compounds have actions, to different individual extents, in the proximal tubule, thick ascending limb, and early distal tubule and are known as 'polyvalent' diuretics. Finally, there is a mixed group of weak or adjunctive diuretics which includes the vasodilator xanthines such as aminophylline, and the osmotically active compounds such as mannitol. The metabolic consequences of continued diuretic usage are considered along with non-metabolic sequelae such as ototoxicity or interactions with other concurrent treatments. The relationships between the clinical benefits conferred and the potential harms generated by long term diuretic therapy are also discussed.

Amiloride↗
PubMed1986

Diuretic drugs. Progress in clinical pharmacology.

Oral diuretics are amongst the most widely used drugs in clinical practice today. Their discovery close on thirty years ago remains a major milestone in therapeutic progress. Though originally designed for treating heart failure, diuretics are more commonly prescribed, worldwide, in hypertension than for relief of oedema. Since the introduction of chlorothiazide, diuretic development has passed through a series of distinct stages. The thiazide era was followed by the 'high-ceiling' diuretics, the antikaliuretics and, more recently, polyvalent agents that cause both saluresis and uricosuria. Alongside these synthetic achievements, major advances have occurred in the knowledge of nephron function and ion transport mechanisms. These have acted as stimulus to the design of novel categories of diuretics. The practising clinician thus has a wide range of available diuretics to choose from. The most appropriate choice of an agent aimed at the relief of symptoms with minimal adverse effects requires an understanding of where and how diuretics act within their primary target organ, the kidney. Whereas various procedures, ranging from micropuncture to the study of brush border membrane vesicles, have been utilised experimentally, investigation of the mode and sites of action of diuretics in man has largely depended on application of clearance methodology. Refinements in analytical chemistry have encouraged study of the pharmacokinetic and metabolic fate of diuretics. Taken together, available evidence shows that most diuretics exert their saluretic action from the intraluminal aspect of the renal tubules. The time-course of drug delivery, as well as total quantity of drug transported into the lumen determine the cumulative drug response. Exceptions are muzolimine and the aldosterone antagonists which act at the peritubular membrane. Distinctive stereospecific effects on luminal tubular ion transport occur with indacrinone and etozoline. The clinical use of diuretics often involves concurrent administration with other drugs. The mechanisms involved in a number of the resulting pharmacodynamic and pharmacokinetic interactions have considerable relevance in patient management. Notable examples of these interactions are the blunting of diuretic action by non-steroidal anti-inflammatory agents and the diuretic-induced diminution in the renal clearance of lithium salts.

Age Factors↗
PubMed2002

Diabetes insipidus in children: pathophysiology, diagnosis and management.

In diabetes insipidus, the amount of water ingested and the quantity and concentration of urine produced needs to be carefully regulated if fluid volume and osmolality are to be maintained within the normal range. One of the principal mechanisms controlling urine output is vasopressin which is released from the posterior pituitary gland and enhances water reabsorption from the renal collecting duct. In diabetes insipidus, the excessive production of dilute urine, and the causes of this clinical picture can be divided into three main groups: the first is primary polydipsia where the amount of fluid ingested is inappropriately large; the second group is cranial diabetes insipidus where the production of vasopressin is abnormally low; and, the third group is nephrogenic diabetes insipidus where the kidney response to vasopressin is impaired. The history and examination may suggest an underlying explanation for diabetes insipidus but a range of baseline and more extensive investigations may be required before a diagnosis can be reached. These investigations are not without risk, and the results need to be interpreted carefully because children do not always segregate neatly into a particular diagnostic category on the basis of one test alone. Children with cranial diabetes insipidus typically respond to arginine vasopressin or its manufactured analogue, desmopressin, with an increase in urine osmolality and an associated reduction in urine output. Such children usually require neuroimaging to look for evidence of evolving CNS pathology, such as an intracranial tumour. Vasopressin "replacement" with desmopressin is the treatment of choice in patients with cranial diabetes insipidus although extreme caution is required when treating babies or small children because of the danger of fluid overload. Abnormal production of other pituitary hormones in children with CNS disease can also influence fluid balance. Nephrogenic diabetes insipidus can be due to abnormal electrolyte concentrations, therefore these should be measured as part of the initial assessment. In a small number of children the defect is a primary abnormality of the vasopressin receptor or one of the water channel proteins (aquaporins) involved in water transport. The treatment of these patients is difficult and typically involves therapy with a diuretic such as chlorothiazide, as well as indomethacin. These agents enhance urine osmolality by their effect on circulating volume and renal solute and water handling. The fluid intake of most young children with primary polydipsia can be safely reduced to a more appropriate level.

Adolescent↗
PubMed2002

The second activating glucokinase mutation (A456V): implications for glucose homeostasis and diabetes therapy.

In this study, a second case of hyperinsulinemic hypoglycemia due to activation of glucokinase is reported. The 14-year-old proband had a history of neonatal hypoglycemia, treated with diazoxide. He was admitted with coma and convulsions due to nonketotic hypoglycemia. His BMI was 34 kg/m(2), and his fasting blood glucose ranged from 2.1 to 2.7 mmol/l, associated with inappropriately high serum levels of insulin, C-peptide, and proinsulin. An oral glucose tolerance test (OGTT) showed exaggerated responses of these peptides followed by profound hypoglycemia. Treatment with diazoxide and chlorothiazide was effective. His mother never had clinical hypoglycemic symptoms, even though her fasting blood glucose ranged from 2.9 to 3.5 mmol/l. Increases in serum insulin, C-peptide, and proinsulin in response to an OGTT suggested a lower threshold for glucose-stimulated insulin release (GSIR). Screening for mutations in candidate genes revealed a heterozygous glucokinase mutation in exon 10, substituting valine for alanine at codon 456 (A456V) in the proband and his mother. The purified recombinant glutathionyl S-transferase fusion protein of the A456V glucokinase revealed a decreased glucose S(0.5) (the concentration of glucose needed to achieve the half-maximal rate of phosphorylation) from 8.04 (wild-type) to 2.53 mmol/l. The mutant's Hill coefficient was decreased, and its maximal specific activity k(cat) was increased. Mathematical modeling predicted a markedly lowered GSIR threshold of 1.5 mmol/l. The theoretical and practical implications are manifold and significant.

Adolescent↗
PubMed2000

Epithelial magnesium transport and regulation by the kidney.

Magnesium is the fourth most abundant cation in the body and the second most common cation in the intracellular fluid. It is the kidney that provides the most sensitive control for magnesium balance. About a 80% of the total serum magnesium is ultrafilterable through the glomerular membrane. In all of the mammalian species studied to date, the proximal tubule of the adult animal reabsorbs only a small fraction, 10-15%, of the filtered magnesium. Unlike the adult proximal convoluted tubule that of young rats (aged 13-15 days) reabsorbs 50-60% of filtered magnesium along the proximal tubule together with sodium, calcium, and water. Micropuncture experiments, in every species studied to date, indicates that a large part (approximately 60%) of the filtered magnesium is reabsorbed in the loop of Henle. Magnesium reabsorption in the loop occurs within the cortical thick ascending limb (cTAL) by passive means driven by the transepithelial voltage through the paracellular pathway. Micropuncture experiments have clearly showed that the superficial distal tubule reabsorbs significant amounts of magnesium. Unlike the thick ascending limb of the loop of Henle, magnesium reabsorption in the distal tubule is transcellular and active in nature. Many hormones and nonhormonal factors influence renal magnesium reabsorption to variable extent in the cTAL and distal tubule. Moreover, nonhormonal factors may have important implications on hormonal controls of renal magnesium conservation. Dietary magnesium restriction leads to renal magnesium conservation with diminished urinary magnesium excretion. Adaptation of magnesium transport with dietary magnesium restriction occurs in both the cTAL and distal tubule. Elevation of plasma magnesium or calcium concentration inhibits magnesium and calcium reabsorption leading to hypermagnesiuria and hypercalciuria. The identification of an extracellular Ca2+/Mg2+ -sensing receptor located on the peritubular side of cTAL and distal tubule cells explains this phenomenon. Loop diuretics, such as furosemide and bumetanide, diminish salt absorption in the cTAL whereas the distally acting diuretics, amiloride and chlorothiazide stimulate magnesium reabsorption within the distal convoluted tubule. Finally, metabolic acidosis, potassium depletion or phosphate restriction can diminish magnesium reabsorption within the loop and distal tubule. Research in the 90's have greatly contributed to our understanding of renal magnesium handling.

Animals↗
PubMed1990

Trends in prescribing of antihypertensive drugs in Australia, 1977-1987.

Prescribing of hypotensive agents, beta-blockers and diuretics was analysed using data from the Pharmaceutical Benefits Scheme, adjusted to reflect prescribing for hypertension, over 1977-1987. Prescribing of these three drug groups combined increased by approximately 50% over the period. Notable trends were decreased prescribing of bendrofluazide, chlorothiazide and methyldopa and increased prescribing of hydrochlorothiazide with amiloride, atenolol, metoprolol and prazosin, and, most recently, captopril and enalapril. The increase in prescribing of drugs for hypertension, combined with the choice of more expensive drugs, has resulted in a substantial increase in the drug costs associated with treating hypertension.

Adrenergic beta-Antagonists↗
PubMed1999

[Study on the antidiuretic efficacy and mechanism of indapamide in central diabetes insipidus].

OBJECTIVE: To investigate the efficacy and antidiuretic mechanism of indapamide in central diabetes insipidus. METHODS: We observed eight patients with central diabetes insipidus treated by indapamide (2.5-7.5 mg.d-1) or dihydro-chlorothiazide (50-70 mg.d-1) or carbamazepine (150-300 mg.d-1) for 8 days with randomized block design. The therapy was changed twice in sequence after 4 days without treatment. Urine output and indexes of water metabolism were also observed. RESULTS: The urine output was reduced on the 4th day and 8th day with each therapy. The serum potassium and chloride concentration was decreased and renin activity was increased on the 4th and 8th day with indapamide therapy. CONCLUSION: Indapamide has antidiuretic action on central diabetes insipidus. The action may result from the changes of hydroelectrolytes and renin-angiotensin-aldosterone system.

Adolescent↗
PubMed1992

[Massive natriuresis and polyuria after triple craniocervical subarachnoid hemorrhage: cerebral salt wasting syndrome?].

A thirty-year-old male patient suffered subarachnoidal haemorrhage from an angioma positioned in the cranio-cervical transition. After rebleeding twice the patient developed a hydrocephalus internus malresorptivus and excessive natriuresis and polyuria, accompanied by depressed renin activity and extremely low aldosterone plasma levels. Neither fluid restriction and sodium substitution, nor administration of hydro-chlorothiazide/indomethacin affected natriuresis and polyuria. It was only after treatment with fludrocortisone-acetate/hydrocortisone that hyponatraemia and polyuria were resolved. At the same time a ventriculo-peritoneal shunt was applied. Differential diagnosis excluded the syndromes of inadequate antidiuretic hormone secretion, renal and cerebral diabetes insipidus, osmotic receptor hypofunction, chronic renal dysfunction and tubular necrosis. Natriuresis and polyuria developed under dexamethasone therapy. Since patient history, physical examination and laboratory criteria could not explain the electrolyte and fluid imbalance, this might be attributed to the hydrocephalus. Similar disturbances have been reported from other patients with intracranial disorders. Mechanical pressure exercised on the hypothalamus might cause the disturbance of fluid and sodium balance. Assuming a cerebral salt wasting syndrome, a putative natriuretic factor coming from the brain or an imbalance in the cerebral renin-angiotensin-system, as described in rats and dogs, must be discussed.

Adult↗
PubMed1992

New histopathologic findings in drug eruptions.

Several new findings associated with hyperpigmentation have been reported in the past decade, the most notable being amiodarone-induced hyperpigmentation, which was shown to demonstrate both a lymphocytic dermatitis as well as yellowish brown granules that can be found within several cell types. The nature of this material has not been elucidated, although the drug or one of its metabolites composes at least a portion of the granules. The nature of the clofazimine-induced hyperpigmentation was shown to be caused by the accumulation of a ceroid lipofuscin within lipid-laden macrophages. Several chemotherapy-induced clinical and histologic changes have been reported in the past decade because of new chemotherapeutic drugs, better recognition of histologic reaction patterns, and the use of higher dosages by oncologists. A unique dermatitis, cutaneous eruption of lymphocyte recovery--although not directly due to use of chemotherapeutic agents--occurs after the return of immunocompetent lymphocytes in the peripheral circulation and skin, producing a maculopapular eruption that demonstrates a nonspecific superficial perivascular dermatitis on biopsy. Another clinically specific reaction, chemotherapy-induced acral erythema, demonstrates a nonspecific histologic pattern characterized by an interface dermatitis. Specific histologic patterns were reported for reactions following use of etoposide--starburst cells--and of busulfan--large atypical keratinocytes. There have been reports of new reactions due to chemotherapeutic agents involving sweat glands: neutrophilic eccrine hidradenitis, characterized by neutrophils and necrosis; and syringosquamous metaplasia, a histologic reaction of the sweat duct characterized by squamous metaplasia. New inflammatory reaction patterns include drug-induced generalized pustular toxic erythema, which histologically shows subcorneal pustules and occasional eosinophils. Cephalosporins were reported to produce a syndrome that clinically and histologically resembles pemphigus. Naproxen is reported to produce a clinical and histologic reaction similar to porphyria cutanea tarda. Quinine and piroxicam both induce a photosensitive dermatitis that histologically shows a nonspecific spongiotic dermatitis. A histologically unique reaction pattern manifesting as a lichenoid giant cell dermatitis may be produced by use of either methyldopa or chlorothiazide. Both phenytoin and carbamazepine produce a dermatitis that histologically imitates mycosis fungoides. Finally, phytonadione injections may produce a clinical and histologic reaction that resembles morphea.

Amiodarone↗