[Effects of acetazolamide (Diamox, Glaupax) on tear production]

In view of personal clinical observations, it appeared possible that a therapy with the carboanhydrase inhibitor acetazolamide leads to a reduction of tear production and induces a dry eye syndrome. Tear secretion was therefore measured by Schirmer tests in a control group of 66 patients after cataract surgery and in a test group of 20 patients who were treated with acetazolamide (Diamox, Glaupax) on the day after the cataract operation. The results were subjected to a statistical analysis with 3-factor anova. The cataract operation induced a significant increase of tear flow. Independent of this effect, administration of the carboanhydrase inhibitor caused a significant decrease of tear production, both in the operated eyes and the untouched fellow eyes.

Calcium metabolism in acidotic patients induced by carbonic anhydrase inhibitors: responses to citrate

Calcium metabolism and its response to citrate were examined in 51 patients with glaucoma receiving carbonic anhydrase inhibitors (acetazolamide or methazolamide). Metabolic acidosis, hypocitraturia and increased incidence of nephrolithiasis were induced by both drugs. However, the acidosis was milder with methazolamide administration. Normocalciuria was observed in 29 patients and was shown to be a result of low filtered calcium. Renal hypercalciuria in 16 patients was associated with elevated parathyroid hormone but nephrogenic cyclic adenosine monophosphate remained within normal limits. Citrate in the form of potassium citrate (4.3 mmol.) and sodium citrate (4.0 mmol.) did not correct the metabolic acidosis or hypocitraturia but consistently decreased fasting and 24-hour urinary calcium excretion in patients with renal hypercalciuria. This event did not occur in patients with normocalciuria or absorptive hypercalciuria. These results suggest that a small amount of citrate could reverse renal hypercalciuria without correcting the metabolic acidosis.

Acetazolamide for alkalinisation of urine in patients receiving high-dose methotrexate

Acetazolamide, 500 mg 6 hourly, has been used to alkalinise the urine in patients receiving high dose methotrexate. A urinary pH of greater than 7.5 was achieved in every cycle (13 cycles in 10 patients). In 6 cycles a single supplementary dose of sodium bicarbonate was necessary. Plasma methotrexate levels fell satisfactorily at 24 and 48 h. Acetazolamide is a simple and effective method of achieving urinary alkalinisation with advantages over oral and intravenous bicarbonate.

Acetazolamide-associated aplastic anaemia

Eleven cases of acetazolamide-associated aplastic anaemia were reported in Sweden during a 17-year period. There were six women and five men with a median age of 71 years (range 63-85 years). The median dose of acetazolamide was 500 mg, and the median duration of treatment was 3 months (range 2-71 months). Ten of the eleven patients died, all within 8 weeks after detection of their aplastic anaemia. The relative risk of developing aplastic anaemia when taking acetazolamide was 13.3 (95% confidence limits (CL); 6.8-25.3). The estimated incidence of reported acetazolamide-associated aplastic anaemia is approximately one in 18,000 patient years. The results strongly indicate that acetazolamide treatment is associated with a substantial increase in the risk of developing aplastic anaemia.

Chronic acetazolamide monotherapy in the treatment of juvenile myoclonic epilepsy

We reviewed the charts of 84 patients with juvenile myoclonic epilepsy (JME) whom we had followed over the past 12 years, and identified 51 treated with acetazolamide (AZM) either because of a poor response to conventional antiepileptic drugs or to avoid valproate-associated adverse effects. Among the 51 we could isolate the effect of AZM on the generalized tonic-clonic seizures (GTCS) of JME in thirty-one. Chronic AZM monotherapy controlled GTCS in 14 of 31 patients. Most tolerated AZM very well; 5, however, developed renal calculi. Chronic AZM monotherapy controls GTCS in some patients with JME, but the development of renal calculi may limit its usefulness.

Familial paroxysmal kinesigenic ataxia and continuous myokymia

A large family with paroxysmal ataxia and continuous myokymic discharges is described. The disorder is of autosomal dominant inheritance. During attacks coordination of movements and balance are disturbed; often a postural tremor of the head and the hands and fine twitching in some of the facial and hand muscles are present. The attacks usually last a few minutes and may occur several times per day. They first appear in childhood and tend to abate after early adulthood. The attacks are frequently precipitated by kinesigenic stimuli similar to those in paroxysmal kinesigenic choreoathetosis. Their occurrence can be reduced or prevented by carbonic anhydrase inhibitors. Between attacks a slight postural tremor and ataxia was found in a few of the elderly affected members. Fine rippling myokymia was obvious in a few and could be detected on close inspection in about half of the adults. Electromyography (EMG) showed myokymic discharges in all affected members. The characteristics and reactivity of this myokymic activity suggest multiple impulse generation in the peripheral nerves.

Cerebral blood flow and end-tidal PCO2 during prolonged acetazolamide treatment in humans

One oral dose of 1,000 mg of acetazolamide caused an acute 38% increase in cerebral blood flow (CBF) in eight healthy volunteers. During the following 10 days the subjects took 1,000 mg acetazolamide daily. CBF normalized within the first 2 days. The drug induced mild hyperventilation, gradually decreasing alveolar PCO2 to 70% of the control value at the end of the treatment period. In healthy humans the hyperventilation will not increase brain oxygenation significantly at sea level. But at high altitudes the enhanced ventilatory drive will improve oxygenation of the brain, and this may account for the beneficial effects of the drug on the symptoms of acute mountain sickness. During the treatment there was a significant 10% decrease of the hematocrit but an unaltered hemoglobin concentration. In combination with data in the literature our studies suggest that the initial CBF increase is a consequence of a transient extracellular acidosis dilating brain arterioles, whereas increased ventilatory drive results from a gradually increasing mild intracellular acidosis in the brain.

Possible association between acetazolamide administration during pregnancy and metabolic disorders in the newborn

Development of metabolic acidosis, hypocalcemia and hypomagnesemia in a preterm infant whose mother was treated with acetazolamide throughout pregnancy is described. These neonatal metabolic alterations possibly related to acetazolamide administration in pregnancy have not been previously described in the literature. The metabolic acidosis was transient and resolved spontaneously despite breast feeding and continued administration of acetazolamide to the mother. Hypocalcemia and hypomagnesemia resolved quickly with appropriate treatment with calcium gluconate and magnesium sulphate, respectively. At follow-up at ages 1, 3 and 8 months, the baby showed mild hypertonicity of the lower limbs requiring physiotherapy.

Severe metabolic acidosis and disturbances of calcium metabolism induced by acetazolamide in patients on haemodialysis

1. To investigate mechanisms of extrarenal buffering in uraemic acidosis, we studied the effects of the carbonic anhydrase inhibitor, acetazolamide, in normal subjects and in patients with end-stage kidney disease on maintenance haemodialysis with virtually no urine output. 2. Acetazolamide (500 mg) was administered daily for 7 days, after pretreatment for 1 month with 1,25-dihydroxyvitamin D (n = 12) or placebo (n = 12); only placebo was administered to a third group (n = 12) of haemodialysis patients. In addition, acetazolamide was administered to normal control subjects (n = 12). 3. Treatment with acetazolamide resulted in a more marked metabolic acidosis in haemodialysis patients than in normal control subjects and the effect in haemodialysis patients was attenuated by prior treatment with 1,25-dihydroxyvitamin D. 4. The administration of acetazolamide to haemodialysis patients led to an increase in serum inorganic phosphorus, bone isoenzyme of alkaline phosphatase and parathyroid hormone, and a reduction in serum calcium, whereas acetazolamide had no effect on these variables in normal subjects. In contrast, in the haemodialysis patients previously treated with 1,25-dihydroxyvitamin D, acetazolamide increased serum inorganic phosphorus, bone isoenzyme of alkaline phosphatase, parathyroid hormone and serum calcium. 5. We hypothesize that the metabolic acidosis induced by acetazolamide in haemodialysis patients may result from interference with the mechanisms of extrarenal buffering. 6. As parathyroid hormone, 1,25-dihydroxyvitamin D and carbonic anhydrase are thought to be involved in bone buffering, we suggest that the marked acidosis seen in haemodialysis patients treated with acetazolamide may be due to impaired parathyroid hormone-mediated bone buffering.

Epidemiologic approach to open-angle glaucoma: 2. Survival analysis of adverse drug reactions. Report of the Canadian Ocular Adverse Drug Reaction Registry Program. The Collaborative Glaucoma Study Group

Medical treatment, intraocular pressure (IOP) and adverse drug reactions were recorded in a prospective multicentre study of 71 unselected, newly diagnosed cases of open-angle glaucoma. Eight ophthalmologists recorded standard information at five visits over a mean interval of 12.1 months. No limitations were imposed on the choice of drugs or interval between visits. The IOP was satisfactorily controlled throughout the follow-up period with the first drug prescribed in 36% of eyes. In an additional 10% to 13% the IOP was stabilized with alternative therapy, prescribed for approximately one-third of eyes per visit. A total of 27 patients reported 18 severe and 31 mild suspected adverse reactions during the follow-up period. Survival analysis showed that there was no significant difference between the proportions of patients continuing treatment with the first, second and third drug prescribed (half-life of treatment approximately 210 days in all three cases). However, when only changes for unsatisfactory pressure were considered, the half-life of treatment was significantly longer, 350 days (p = 0.02).

Use of acetazolamide as an adjunct to carbamazepine in refractory partial seizures

Acetazolamide (Diamox) (AZM) was evaluated as an adjunct to carbamazepine (CBZ) monotherapy in 48 refractory partial seizure patients at a tertiary care referral center. Patient ages ranged from 6 to 64 years (average 28 years). Seizure frequencies for the pre-AZM baseline period (CBZ monotherapy) were compared with the seizure frequencies at different daily doses of AZM. Patients with a 50% decrease in seizure frequency were considered responders. Twenty-one patients were responders (44%) and three became completely seizure-free. Effective doses ranged from 3.8 to 22.0 mg/kg/day. Effective plasma concentrations ranged from 1 to 22 micrograms/ml in selected patients. Durations of response time to AZM ranged from 3 to 30 months (average 12.9 months). Three patients lost response, one temporarily. Side effects were seen in 10 patients, requiring discontinuation in three.

Tamm-Horsfall protein accumulation in glomeruli during acetazolamide-induced acute renal failure

A patient with ocular hypertension was treated with acetazolamide. Acute renal failure developed rapidly and renal biopsy showed mild tubular lesions and crystal formation in a tubular lumen. By immunofluorescence studies with a monoclonal antibody, Tamm-Horsfall protein, normally absent from the proximal segments of the nephron, was detected in most glomeruli. This strongly suggests that tubular obstruction plays a major part in some cases of acetazolamide-induced acute renal failure.

Intraocular pressure changes during hemodialysis: prevention of excessive dialytic rise and development of severe metabolic acidosis following acetazolamide therapy

The response of intraocular pressure (IOP) to hemodialysis was investigated in 55 patients with end-stage kidney disease enrolled in a chronic dialysis program. The mean level of IOP, measured by the Goldman applanation tonometer, before dialysis was slightly lower than that of a control group of 50 healthy subjects (14.9 +/- 2 mm Hg vs 15.6 +/- 1.9 mm Hg. p = .07). During dialysis IOP underwent an excessive rise (7.8 to 12.5 mm Hg) in 10 patients (group 1), remained unchanged (variations below 2 mm Hg) in 41 patients (group 2), and decreased (3.1 to 5.1 mm Hg) in 4 patients (group 3). In group 1 patients, gonioscopy showed a narrow angle between iris and lateral cornea. Conversely, the anterior chamber angle was normal in patients of groups 2 and 3. The effect of a 7-day course of acetazolamide therapy (500 mg per day orally) on IOP was investigated in group 1 patients. Acetazolamide was capable of preventing the excessive IOP rise during dialysis. The mean reduction of such a dialytic rise was 8.1 mm Hg. However, despite this effect, in these patients the IOP level after dialysis still remained significantly higher than that of patients of group 2 (18.1 +/- 1 mm Hg vs 14.9 +/- 0.8 mm Hg. p less than .0001). Acetazolamide therapy precipitated in all patients a severe metabolic acidosis (blood pH fell from 7.38 +/- 0.02 to 7.24 +/- 0.03, p less than .0001; and bicarbonate concentration from 21 +/- 2.5 mmol/liter to 12.3 +/- 2.4 mmol/liter, p less than .0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Role of protriptyline and acetazolamide in the sleep apnea/hypopnea syndrome

The role of drug therapy in the treatment of the sleep apnea/hypopnea syndrome is unclear. In a randomised, double-blind, placebo-controlled study, we investigated the value of 14-day therapy with protriptyline (20 mg daily) or acetazolamide (250 mg 4 times per day) on symptoms and on the frequency of apneas, hypopneas, arousals, and 4% desaturations in 10 patients with obstructive sleep apnea/hypopnea syndrome. Overall, protriptyline did not have a significant effect either on symptoms or on any of the above polysomnographic criteria. Acetazolamide reduced the apnea/hypopnea frequency [placebo 50 +/- 26 (SD); acetazolamide 26 +/- 20/h of sleep, p less than 0.03] and tended to decrease the frequency of 4% desaturations (placebo 29 +/- 20; acetazolamide 19 +/- 16/h of sleep, p = 0.06). Despite these physiological improvements, acetazolamide did not significantly improve symptoms and paraesthesiae were common. Contrary to earlier studies, we conclude that protriptyline may have a limited role in the treatment of the sleep apnea syndrome. The reason why acetazolamide produced a physiological, but not a symptomatic, response requires further investigation.

Enhancement of the ocular hypotensive effect of acetazolamide by diflunisal

We studied the effect of diflunisal on intraocular pressure in patients with glaucoma who were receiving maximally tolerated therapy. Diflunisal therapy, 500 mg twice daily, was started in 48 patients for one week. No changes were made in their regular antiglaucoma medications. Intraocular pressure was reduced an additional 3.8 +/- 3.1 mm Hg (+/- S.D.) in the acetazolamide-treated patients (P less than .0001) and 1.6 +/- 1.5 mm Hg in methazolamide-treated patients (P less than .02), while no significant reduction in intraocular pressure was found in patients receiving topical medications alone. In 15 acetazolamide-treated patients, total plasma concentrations of acetazolamide after diflunisal therapy were significantly higher than the prediflunisal levels, suggesting a modest decrease in renal excretion. In seven acetazolamide-treated patients, free plasma concentrations of acetazolamide were found to increase 5.6-fold after diflunisal therapy. We concluded that diflunisal potentiated the ocular hypotensive effect of acetazolamide by increasing its free plasma level.

Treatment of chronic macular edema with acetazolamide

In a prospective study, 41 patients with documented chronic macular edema of various causes were entered into a therapeutic trial of acetazolamide sodium, a carbonic anhydrase inhibitor. Each patient received a five-cycle cross-over regimen of treatment/no treatment with a further two cycles of cross-over with another diuretic, cyclopenthiazide, which does not inhibit carbonic anhydrase. At each cross-over patients were examined for evidence of macular edema. Sixteen of 41 patients showed a reproducible response to acetazolamide with partial or complete resolution of edema and improvement of visual acuity. The therapeutic effect occurred in more than half of the patients with inherited outer retinal disease or uveitis, but in none with primary retinal vascular disorders. There was no correlation between the response to treatment and the extent or duration of the edema. No influence of cyclopenthiazide on macular edema was detected.

Effects of acetazolamide in patients with the sleep apnoea syndrome

There is as yet no convincing evidence that acetazolamide, a carbonic anhydrase inhibitor, is effective in obstructive sleep apnoea. A study was therefore designed to examine the effect of acetazolamide (250 mg/day) on sleep events and ventilatory control during wakefulness in nine patients with the sleep apnoea syndrome. In eight of the nine patients the apnoea index and the total duration of apnoea were reduced by acetazolamide, and the mean (SEM) apnoea index of all patients changed from 25.0 (6.7) to 18.1 (5.8) episodes an hour. Furthermore, the total time of arterial oxygen desaturation (SaO2)--more than 4% depression in SaO2 from the baseline sleeping level--divided by total sleep time was also significantly decreased and its mean (SEM) value improved from 24.1 (7.9) to 13.6 (4.8)% of total sleep time. Five of the seven patients with varying degrees of daytime hypersomnolence had their symptoms obviously improved. There was no patient whose predominant type of apnoea was converted from the obstructive to the central type, or vice versa. In the studies of wakefulness, metabolic acidosis, an increase of arterial oxygen tension (PaO2) and a decrease of arterial carbon dioxide tension (PaCO2) were observed. The slopes of the occlusion pressure response and the ventilatory response to carbon dioxide increased, and the carbon dioxide ventilatory response line shifted to the left. It is suggested that acetazolamide cannot remove apnoea completely but has a beneficial effect in mild cases of obstructive sleep apnoea through an augmentation of central (CO2, H+) drive and a stabilising effect on ventilatory control.

A randomized trial of dexamethasone and acetazolamide for acute mountain sickness prophylaxis

Forty-seven climbers participated in a double-blind, randomized trial comparing acetazolamide 250 mg, dexamethasone 4 mg, and placebo every eight hours as prophylaxis for acute mountain sickness during rapid, active ascent of Mount Rainier (elevation 4,392 m). Forty-two subjects (89.4 percent) achieved the summit in an average of 34.5 hours after leaving sea level. At the summit or high point attained above base camp, the group taking dexamethasone reported less headache, tiredness, dizziness, nausea, clumsiness, and a greater sense of feeling refreshed (p less than or equal to 0.05). In addition, they reported fewer problems of runny nose and feeling cold, symptoms unrelated to acute mountain sickness. The acetazolamide group differed significantly (p less than or equal to 0.05) from other groups at low elevations (1,300 to 1,600 m), in that they experienced more feelings of nausea and tiredness, and they were less refreshed. These drug side effects probably obscured the previously established prophylactic effects of acetazolamide for acute mountain sickness. Separate analysis of an acetazolamide subgroup that did not experience side effects at low elevations revealed a prophylactic effect of acetazolamide similar in magnitude to the dexamethasone effect but lacking the euphoric effects of dexamethasone. This study demonstrates that prophylaxis with dexamethasone can reduce the symptoms associated with acute mountain sickness during active ascent and that acetazolamide can cause side effects that may limit its effectiveness as prophylaxis against the disease.

Hypokalemic periodic paralysis with unusual responses to acetazolamide and sympathomimetics

Five members in three generations of a family were affected by an illness that had many clinical features of the hypokalemic form of periodic paralysis (HPP). The serum potassium was either moderately reduced or normal during attacks, and there was no evidence of myotonia or cold-intolerance. All of the patients improved to a variable degree with oral potassium supplements, and 3 responded favorably to triamterene. The usually beneficial drug acetazolamide, however, invariably caused weakness in these patients, an effect previously described in only one other family with HPP. In addition, amphetamine-like sympathomimetic drugs effectively aborted or prevented paralysis in several members. Muscle biopsy in two patients revealed some unusual features, and electromyography showed myopathic potentials. There was no evidence of diabetes. The urine electrolyte concentrations during glucose tolerance tests, however, were different from those previously reported in HPP. This family may represent a variant form of HPP.

The rCBF response to Diamox in normal subjects and cerebrovascular disease patients

Age-related norms for the regional cerebral blood flow (rCBF) response to Diamox (acetazolamide) were based on studies of 55 normal subjects at rest and on studies of 33 of these 55 normal subjects following an intravenous injection of Diamox (22 mg/kg). After the Diamox injection, rCBF increased at all locations measured in all subjects. On average, rCBF increased 1.7 times. The following were found for rCBF in both resting and Diamox-treated subjects: 1) rCBF decreased significantly with increasing age; 2) slope and intercept for the regression of rCBF on age were largest for frontal detectors, intermediate for parietal detectors, and smallest for occipital detectors; 3) rCBF hyperfrontality was most noticeable in younger subjects; 4) in subjects of any age, 95% confidence intervals for rCBF were relatively large (expected value +/- 30%) and lower 95% confidence intervals for Diamox rCBF tended to overlap the upper 95% confidence intervals for resting rCBF; and 5) side-to-side percentage difference in rCBF did not have a significant regression on age and tended to be less than 10% to 20%. Diamox did not have an important effect on blood pressure, pulse rate, or respiratory rate. The normative data for the rCBF response to Diamox was used in evaluating 20 patients with cerebrovascular disease. Forty percent of these patients, all of whom exhibited angiographic evidence of potentially hemodynamically significant lesions, had normal rCBF at rest and after Diamox injection. Twenty percent had normal resting flows with abnormal Diamox-activated flows. Asymmetry in rCBF was the most sensitive indicator of a potential abnormality in cerebral perfusion. Thirty percent of the abnormal studies showed only significant asymmetry. It is suggested that rCBF studies at rest and after Diamox treatment, with age-related norms, may be useful in the management of patients with cerebrovascular disease.

Organic impotence associated with carbonic anhydrase inhibitor therapy for glaucoma

Sexual impotence developed in four patients who were receiving carbonic anhydrase inhibitor therapy for glaucoma. Whereas decreased libido has been reported as a side effect of carbonic anhydrase inhibitor therapy, organic impotence has not been documented as an isolated finding.

Chronic and recurrent choroidal detachment after glaucoma filtering surgery

Chronic and recurrent choroidal (ciliochoroidal) detachments developed following glaucoma filtration surgery in 14 eyes of 13 patients during a 9-year period. Three specific subgroups were identified: recurrent, inflammatory, and chronic (present for more than 6 months). The factors that may be related to the development of chronic and recurrent choroidal detachments included patient age (mean, 68.8 years), systemic hypertension or atherosclerotic heart disease, hyperopia, aqueous suppressant therapy, ocular inflammation, and full-thickness filtration surgery. A total of 46 choroidal detachments in 14 eyes were recorded and required drainage of suprachoroidal fluid on 34 occasions. All eyes developed visually significant cataracts, and complete resolution of the recurrent or chronic choroidal detachment occurred following cataract extraction in six eyes. Treatment of chronic and recurrent choroidal detachments should include intense therapy of ocular inflammation, discontinuation of medications that can incite ocular inflammation, discontinuation of topical and systemic aqueous suppressant therapy, and when a visually significant cataract is present, cataract extraction combined with a choroidal tap should be performed.

Urine composition and stone formation during treatment with acetazolamide

Twelve patients who formed renal stones during acetazolamide treatment for glaucoma were studied. Calcium phosphate was the dominating component in the stones. Long term treatment with acetazolamide decreased urinary citrate markedly, which will result in an increased ion-activity product of calcium phosphate and a decreased inhibiting property of urine on calcium phosphate crystallization. The treatment also increased urinary oxalate which together with a low citrate might increase the risk of calcium oxalate crystallization. However, an estimate of the ion-activity product of calcium oxalate in urine (AP [CaOx]-index) was unaffected by the treatment and calcium oxalate was a minor component of the stones.

Toxic interaction between acetazolamide and salicylate: case reports and a pharmacokinetic explanation

Two elderly patients, who were chronically receiving aspirin, developed lethargy, incontinence, and confusion after dosing with acetazolamide. Unbound plasma acetazolamide concentrations were elevated and plasma protein binding was reduced, suggesting an interaction with aspirin. In vitro studies demonstrated a concentration-dependent effect of salicylate on acetazolamide binding to serum proteins. At a therapeutic serum acetazolamide level of 8.0 micrograms/ml, the unbound percentage of acetazolamide in serum was 3.3% and increased to 11.0% and 30.0%, with serum salicylate levels of 200 and 386 micrograms/ml, respectively. Furthermore, the apparent association constant of acetazolamide for binding to serum proteins was decreased by 58% and 86% of its control value at these respective salicylate concentrations. The maximal binding capacity of serum for acetazolamide was not affected by salicylate. Pharmacokinetic studies in four volunteers showed that the plasma protein binding and renal clearance of acetazolamide were significantly reduced during chronic salicylate dosing. Salicylate appears to competitively inhibit the plasma protein binding of acetazolamide and simultaneously to inhibit acetazolamide renal tubular secretion. Caution is advised when acetazolamide and salicylate are used concurrently.

Severe mixed acidosis by combined therapy with acetazolamide and timolol eyedrops

A patient with chronic obstructive lung disease developed a severe mixed acidosis after treatment for glaucoma with a combination of carbonic anhydrase inhibitor and beta adrenergic blocking agent in normal doses.

[Lithium poisoning. 2 unpublished interactions: acetazolamide and niflumic acid]

Two lithium intoxication cases due to an association with acetazolamide and niflumic acid are reported. They confirm the necessity of plasma lithium monitoring when a new drug is added.