Pharyngeal and laryngeal symptoms and signs related to extraesophageal reflux in patients with heartburn in gastroenterology practice: a prospective study.

OBJECTIVES: To describe pharyngeal and laryngeal symptoms and findings in correlation to extraesophageal reflux (EER) in patients with heartburn. DESIGN: A prospective study. SETTING: Patients referred to Department of Gastroenterology, Karolinska University Hospital Huddinge. PARTICIPANTS: Forty-three patients with chronic heartburn as the primary symptom, subdivided on the basis of oesophageal manometry to have gastro-oesophageal reflux disease (GORD) (n = 25) or not (n = 18). MAIN OUTCOME MEASURES: Laryngeal video recordings of 43 patients were examined off-line. The occurrence of symptoms and laryngeal pathology were correlated to the results of 24-h double-probe pH monitoring. RESULTS: Pharyngeal or laryngeal symptoms occurred often or quite often in 72% (18 of 25) of the GORD patients and 61% (11 of 18) of the patients without GORD. EER occurred in 73% (16 of 22) of the GORD patients with laryngeal symptoms and in 38% (6 of 16) of those without GORD but with laryngeal symptoms (P = 0.047). In the multivariate analysis the odds for hoarseness was 17 times higher if the patient had heartburn more than five times a day, compared with patients with heartburn less than once a day (OR 17.8, CI 1.7-405.9; P = 0.01). Cohen's kappa for intrarater reliability was 0.851 (P = 0.001). Laryngeal pathology was found in 56% of the GORD patients and 44% patients without GORD. There was no significant difference in the occurrence of any specific symptom or finding between the patients with and without GORD, nor with and without EER. CONCLUSIONS: Although GORD together with laryngeal symptoms seem to be predictive of EER, there are no specific pharyngeal and laryngeal symptoms or findings that would help distinguishing patients with EER from those without. However, the more frequent the heartburn to the more frequent is hoarseness.

Propranolol increases the complexity of heart rate fluctuations--a mode of antiarrhythmic action?

OBJECTIVE: To study the beta-blocking effect of propranolol on heart rate and arterial blood pressure fluctuations in healthy subjects using linear methods and a set of nonlinear models. METHODS: In a randomized, double-blind, placebo-controlled study, healthy young adults received a 40 mg oral dose of propranolol (n = 12) or placebo (n = 12). The effects of propranolol and placebo were assessed using time series of the RR interval (RRI) and systolic arterial blood pressure (SAP) obtained from continuous ECG and blood pressure signal recordings. Heart rate and systolic arterial blood pressure fluctuations were analyzed using nonlinear and linear methods of time series statistics. RESULTS: Propranolol significantly increased the complexity of heart rate fluctuations in terms of symbol dynamic (SymDyn) entropy and symbol dynamic percentage of forbidden words. Propranolol augmented cross entropy between RRI and SAP and increased fractal dimension of RRI. beta-blockade also affected linear measures of RRI fluctuations by increasing parasympathetic, respiration-related high-frequency (HF) variability and arterial baroreflex-related low-frequency (LF) variability. Propranolol administration, however, had no effect on the complexity of SAP fluctuations assessed using nonlinear time series statistics. CONCLUSIONS: beta-blockade by propranolol has a differential effect on RRI and SAP fluctuations in healthy subjects. Propranolol increases the complexity of RRI fluctuations. The effect is associated with the cardiac vagotonic drug action of propranolol. SAP fluctuations are almost unchanged. The increased complexity of RRI fluctuations may be a beneficial feature of beta-blockade, since many cardiovascular diseases decrease the complexity of RRI time series by dampening cardiovascular reflex actions.

Is pseudosulcus alone a reliable sign of gastroesophago-pharyngeal reflux?

To investigate if laryngeal pseudosulcus (bilateral infraglottic oedema) is a reliable sign of pharyngeal reflux, the video recordings of 59 patients and 18 controls were examined off-line by two phoniatricians. Eleven video segments were duplicated for calculation of intrarater reliability. The frequency of pseudosulcus was correlated to the results of 24-h double-probe pH monitoring. The intrarater reliability was moderate (K = 0.582; P = 0.005). The sensitivity of pseudosulcus in the diagnosis of pharyngeal reflux among the patients was 30% and among the controls it was 0%. The positive predictive value (PPV) of pseudosulcus for patients with pharyngeal and laryngeal symptoms was 67%, while for the controls it was 0%. The negative predictive value (NPV) of pseudosulcus for patients with pharyngeal or laryngeal symptoms was 32% and for the controls it was 64%. The single finding of pseudosulcus is not a very sensitive predictor of pharyngeal reflux but if the patient has laryngeal symptoms and a pseudsulcus, the probability that the patient has pharyngeal reflux is almost 70%.

Vocal fold deposits in autoimmune disease--an unusual cause of hoarseness.

The objective of this study was to evaluate the symptoms and clinical characteristics in patients with autoimmune vocal fold deposits. Fourteen patients underwent videolaryngostroboscopic examination and voice recording. Eleven of the 14 patients underwent rheumatological examination. In all cases, endoscopic examination showed transverse white-yellow band lesions in the middle of the membranous portion of the vocal folds. In most cases, the lesions were bilateral but not exactly opposing each other. The most common voice characteristics were instability and intermittent aphonia. Inflammatory disease was present in 10 patients; five of these had rheumatoid arthritis (RA). No immunological signs common for all patients could be found. The histological examination was consistent with rheumatoid nodules. Vocal fold deposits, occurring most often in patients with RA, is an uncommon cause of hoarseness. Because the patients may have hoarseness as their primary symptom, it is important for otolaryngologists to be familiar with this disorder.

Suppression of viability and acetyl-LDL metabolism in RAW 264 macrophage-like and smooth muscle cells by bisphosphonates in vitro.

Etidronate and clodronate are bisphosphonates that inhibit the development of experimental atherosclerosis. Etidronate decreases the intimamedia thickness of carotid artery even in man. Liposome-encapsulated bisphosphonates inhibit the cellular metabolism of atherogenic, modified low-density lipoprotein (acetyl-LDL) by cultured macrophages. In the present study, the effects of new bisphosphonate tiludronate and nitrogen-containing bisphosphonate alendronate on cell viability and cellular uptake and degradation of acetyl-LDL were investigated in vitro with macrophages and arterial smooth muscle cells, which have a significant role in atherogenesis. Tiludronate and alendronate decreased the viability of RAW 264 macrophages at high concentration (1,000 microM; p < 0.05), while liposome-encapsulated drugs suppressed the viability at concentrations of 30-300 microM. At concentrations greater than or equal to 10 microM, tiludronate and alendronate inhibited the uptake and degradation of acetyl-LDL by RAW 264 cells in a concentration-dependent manner (p < 0.001). None of the bisphosphonates affected the viability of smooth muscle cells, and none but alendronate at a high concentration (1,000 microM) inhibited the uptake and degradation of acetyl-LDL by smooth muscle cells. The results show that tiludronate and alendronate inhibit the atherogenic activity of macrophages in vitro, as shown previously with etidronate and clodronate, providing further evidence for the antiatherogenic effects of bisphosphonates.

Symptoms, laryngeal findings, and 24-hour pH monitoring in patients with suspected gastroesophago-pharyngeal reflux.

OBJECTIVES: To investigate the laryngeal signs and symptoms associated with gastroesophago-pharyngeal reflux (GEPR). STUDY DESIGN: A prospective controlled study. METHODS: Nineteen healthy control subjects and 43 patients, 26 with posterior laryngitis (PL) and 17 with a normal larynx and suspected GEPR, were examined using videolaryngoscopy and 24-hour ambulatory dual-probe pH monitoring. RESULTS: Pharyngeal acid reflux occurred in 18 (69%) patients with PL, in 9 (53%) patients with a normal larynx, and in 5 (26%) healthy control subjects. Multiple-comparison procedure showed that pharyngeal reflux was significantly more prevalent in patients with PL than in the healthy control subjects (P < .05). The laryngoscopic findings in patients with pharyngeal reflux varied from normal mucosa to thickening or edema of the posterior wall of the glottis, which was the most frequent finding in the PL group. Erythema was uncommon; it was found only in patients with verified pharyngeal reflux. There was no difference in symptom profile between the patients with PL and patients with a normal larynx or patients with or without pharyngeal reflux. CONCLUSIONS: Pharyngeal reflux is significantly more prevalent in patients with posterior laryngitis than in healthy control subjects. Moreover, a certain degree of pharyngeal reflux appears to be a normal phenomenon. The most common laryngeal finding in patients with posterior laryngitis is thickening or edema of the posterior wall of the glottis. GEPR does not yield specific laryngeal symptoms. Thus, it is unreliable to base the reflux diagnosis on symptoms alone.

Voice characteristics, effects of voice therapy, and long-term follow-up of contact granuloma patients.

This study evaluates the laryngoscopic findings and voice characteristics of male contact granuloma patients before and after voice therapy and at a follow-up about 9 years later. Pre- and posttherapy recordings as well as follow-up recordings were made for 19 granuloma patients. Pretherapy revealed the most salient perceptual voice characteristics were low pitch, monotony, and a high degree of vocal fry and hyperfunction. Interjudge reliability for these traits was high. Immediately following therapy the healed patients (n = 10) had a decrease in hyperfunction, vocal fry, and monotony, while the unhealed patients (n = 9) had an increase in hyperfunction and vocal fry decreased only marginally. Monotony decreased significantly in this group. As regards the acoustic analyses, no significant differences were found in mean fundamental frequency (F0) or perturbation. At the follow-up assessment 4 patients had granuloma while 15 had normal laryngeal status. Perceptually their voice characteristics resembled those pretherapy independently of the laryngeal findings. The results suggest that reduced hyperfunction and decreased vocal fry may create better circumstances for the healing process at the posterior glottis.

Laryngeal findings in patients with contact granuloma: a long-term follow-up study.

In order to evaluate the long-term outcome of contact granuloma a follow-up study of 59 patients was conducted. Primary treatment consisted mainly of voice therapy or of voice therapy in combination with surgery. A careful history was taken and the patients were examined using videolaryngoscopy. The average follow-up time was 12 years (range 5-20 years). In total, 10 out of 59 patients (17%) had a granuloma at the follow-up examination, 6 of them presenting without subjective symptoms. Another 28 patients had various signs of inflammation of the posterior glottis. The history taken at follow-up revealed that eight patients had had a previous temporary recurrence during the follow-up time. The recurrence frequency was the same for patients who received voice therapy after postoperative recurrence and patients who were treated with voice therapy only. About 80% of the patients had no symptoms at follow-up. The findings of the present study indicate that contact granuloma is one of several manifestations of chronic posterior laryngitis and that it may occur without symptoms.

Influences of nonselective, beta(1)-selective and vasodilatory beta(1)-selective beta-blockers on arterial pulse wave velocity in normotensive subjects.

beta-Adrenoceptor blockers with disparate properties may have differential influences on arterial pulse wave velocity (PWV). Therefore, influences of single medium doses of bisoprolol, propranolol and celiprolol on PWV were compared in healthy subjects. Arterial PWV was obtained from the time delay between flow pulses measured from the root of the aorta and the popliteal artery. Bisoprolol and propranolol decreased arterial PWV more than placebo (P less-than-or-equal to .002) and celiprolol (P<.0001). In conclusion, the acute effects of bisoprolol and propranolol on arterial PWV in normotensive subjects seem to differ from that of celiprolol.

Bisphosphonates and atherosclerosis.

Bisphosphonates are used for the treatment of bone resorption, hypercalcemia, osteoporosis and Paget's disease. Etidronate, pamidronate and clodronate also inhibit the development of experimental atherosclerosis without altering serum lipid profile. Bisphosphonates inhibit the arterial calcification, lipid accumulation and fibrosis. They accumulate extensively in arterial walls and suppress macrophages in atheromatous lesions. In macrophage cultures, bisphosphonates inhibit the cellular accumulation and degradation of atherogenic LDL-cholesterol and foam cell formation. Further, they inhibit various enzymes involved in cell signal transduction and cholesterol biosynthesis. Recently, etidronate has been shown to inhibit the thickening of carotid arterial wall even in man.

Comparison of pharmacokinetics of clodronate after single and repeated doses.

OBJECTIVE: Pharmacokinetics of orally given clodronate disodium, a drug for the treatment of hypercalcemia and bone resorption, were studied after a single dose of 400, 800 and 1600 mg given randomly to 11 healthy volunteers in a crossover manner, in 7-14 hospitalized cancer patients given 400, 800 and 1600 mg twice daily, each dosage for one week, and during the customary therapy in 15 additional cancer patients treated in hospital with 400 mg thrice daily for > or = 2 weeks. METHODS: Clodronate concentrations in serum and urine were measured by capillary gaschromatography with mass-selective detection. Pharmacokinetic parameters were calculated with a three-compartmental model. RESULTS: After a single oral dose to healthy volunteers the absolute clodronate concentrations increased almost dose-dependently. The mean cumulative excretion in urine was 1.72-2.77% of the dose, an interindividual range being from 0.92% to 5.52%. With 800 and 1600 mg twice daily for one week to cancer patients the serum drug concentrations increased almost progressively with increasing the dose. In cancer patients serum drug concentrations were clearly higher and renal drug clearances (mean 25-62 ml/min) lower than in healthy volunteers (mean 123-149 ml/min). The mean urinary excretions were 2.24-3.14% of the dose and interindividual ranges from 0.18% to 19.0%. During the routine cancer therapy with 400 mg thrice daily, the clodronate excretions in urine on two successive days were on an average 3.26% (range 0.0-10.5%). CONCLUSIONS: Absolute concentrations in serum and excretions in urine of orally given clodronate increase dose-dependently, but during the maintenance therapy in hospitalized cancer patients the renal drug clearances seem to be lower than in healthy volunteers. This and the large interindividual variation in kinetics propose therapeutic monitoring of clodronate for optimizing the oral dose of the drug.

Metabolism of modified LDL and foam cell formation in murine macrophage-like RAW 264 cells.

The uptake of modified low density lipoprotein (LDL) by arterial macrophages is a key event in the atherogenesis. We studied 1) the uptake and degradation of modified LDL, 2) LDL recognition by specific receptors, and 3) the foam cell formation with murine macrophage-like RAW 264 cells in vitro. The cells took up and degraded effectively 125I-labeled acetylated LDL (Ac-LDL) and aggregated LDL (Aggr-LDL). Also oxidized LDL (Ox-LDL) was taken up but it was degraded poorly. The degradation of 125I-Ac-LDL was efficiently competed by both unlabeled Ac-LDL and Ox-LDL, whereas the degradation of 125I-Ox-LDL was partially competed by unlabeled Ox-LDL and Aggr-LDL but not at all by unlabeled Ac-LDL. The incubation with increasing concentrations of Ac-LDL, Aggr-LDL or Ox-LDL resulted in marked foam cell formation in the RAW 264 cells. Ox-LDL was cytotoxic at 500 to 1000 microg/ml concentrations. The results show that RAW 264 cells have at least two classes of receptors for modified lipoproteins: one that recognizes both Ox-LDL and Ac-LDL, and is similar to the scavenger receptors, and another that recognizes Ox-LDL but not Ac-LDL. RAW 264 cells are a convenient model cell line for examining the metabolism of modified lipoproteins, not only that of Ac-LDL but also that of Ox-LDL and Aggr-LDL, and cellular accumulation of lipids derived from modified LDL.

A retrospective study of contact granuloma.

OBJECTIVES: This study evaluates the clinical features of contact granuloma and compares the results of voice therapy in operated versus unoperated cases. STUDY DESIGN: Retrospective review of 123 patients with contact granuloma. Thirty-six patients had undergone one or more surgeries before phoniatric consultation. After their final operation, 33 patients had recurrence. The three patients who were cured by operation were not studied further. The course of disease in the 33 patients with recurrence was compared with that of 87 patients who did not have surgery. METHODS: The hospital records were reviewed concerning age, sex, symptoms, side of granuloma, and outcome of treatment. RESULTS: The predominant symptoms were vocal fatigue, vocal discomfort, the need for excessive throat clearing, and hoarseness. The recurrence rate after operation was 92%. Twelve months after voice therapy, 35% of the operated group and 51% of the unoperated group were cured. The patients who had surgery had almost twice as many sessions of voice therapy as the unoperated group, and their mean recovery time was 17 months, compared with 8 months for the unoperated group. CONCLUSIONS: The recurrence rate after surgery was high. Surgery may prolong the recovery time. Subjective symptoms diminished during voice therapy, but we cannot confirm that it was beneficial for the healing process.

Pharmacokinetics of bisphosphonates in rabbits.

Clodronate, pamidronate and etidronate are commonly used bisphosphonates, which accumulate extensively in arteries and some other tissues. We compared their pharmacokinetics in rabbits with those of tiludronate, the drug newly introduced to clinical use. The 14C-labelled drugs were given intravenously and plasma drug levels were monitored for up to 24 hr. The dose-related plasma concentrations of tiludronate and etidronate were clearly higher and decreased more slowly than those of clodronate and pamidronate (P < 0.001). Already at 5 min., the concentrations of tiludronate and etidronate were higher than those of clodronate and pamidronate (P = 0.016). At 24 hr, plasma concentration of tiludronate was 12 +/- 6.6%, of etidronate 18 +/- 2.5%, of clodronate 0.8 +/- 0.2%, and of pamidronate 1.4 +/- 0.4% of the dose per body weight. With the same dose (25 mg/kg), absolute AUC0-24 hr for tiludronate and etidronate was 9-11 times larger than for clodronate. AUC0-24 hr for pamidronate (2.5 mg/kg) was 11% of that for clodronate. Plasma clearance of tiludronate and etidronate was 9-15 times slower than that of clodronate and pamidronate. At 24 hr, the mean tissue-to-plasma ratio of tiludronate for aorta was 1.2-1.6. For bone, spleen, liver and kidneys the ratio varied from 5.4 to 52.6. The results suggest that 1) tiludronate and etidronate are removed from plasma much slower than clodronate and pamidronate, and 2) the potential of tiludronate to concentrate in arteries and bone is generally smaller than previously found with the other bisphosphonates.

Accumulation of bisphosphonates in human artery and their effects on human and rat arterial function in vitro.

Clodronate, etidronate and pamidronate are bisphosphonates introduced in the treatment of hypercalcaemia and osteoporosis. Interestingly, they also inhibit development of experimental atherosclerosis and affect smooth muscle tone of isolated rat tail artery. We have studied in vitro whether these hydrophilic compounds 1) accumulate in the wall of the human artery, 2) influence human arterial tone, and 3) interfere with the vascular action of L-type Ca2+ antagonists. Human internal mammary artery rings were incubated with 14C-labelled bisphosphonates. After a 2-hr incubation, the ratios of artery-to-incubate concentrations with 4 and 40 mumol/l of clodronate were, respectively, 3.0 +/- 0.5 (mean +/- S.E.M.) and 1.3 +/- 0.2, with 4 and 40 mumol/l of etidronate 7.4 +/- 0.9, and 3.2 +/- 0.4, and with 0.4 and 4 mumol/l of pamidronate 4.7 +/- 0.7 and 3.9 +/- 0.8. Both tested bisphosphonates, clodronate and pamidronate, reduced the arterial contractile force induced by alpha-adrenergic stimulation with noradrenaline and membrane depolarization with high concentration of KCl. Clodronate also decreased the arterial contraction induced by cumulative addition of Ca2+ with KCl as the agonist, and had an additive inhibitory effect on this response with the L-type Ca2(+)-channel blocker nifedipine. The results demonstrate that 1) bisphosphonates accumulate markedly in human artery, 2) clodronate and pamidronate reduce human arterial contactile force to alpha-adrenergic and depolarizing stimuli, and 3) as shown with clodronate, bisphosphonates may exert an additive inhibitory effect on human arterial contractions with an L-type Ca2(+)-channel blocker.

Influence of captopril, propranolol, and verapamil on arterial pulse wave velocity and other cardiovascular parameters in healthy volunteers.

OBJECTIVE: The effects of antihypertensive agents on cardiovascular parameters, especially on arterial pulse wave velocity, remain largely unknown in normotensive subjects. Therefore, the present investigation was designed to evaluate acute effects of ACE inhibitor captopril,beta-adrenoceptor blocker propranolol and calcium entry blocker verapamil on cardiovascular and ventilatory function in healthy volunteers. MATERIAL: The influence of single doses of captopril (25 mg), propranolol (40 mg), and verapamil (80 mg) on cardiovascular function and exercise capacity were compared in healthy volunteers in a randomized, double-blind, placebo-controlled fashion. METHODS: Cardiac output and beat-by-beat blood pressure were estimated non-invasively before and after the drug administrations by whole-body impedance cardiography and Finapres finger blood pressure monitoring, respectively. Arterial pulse wave velocity was obtained from the time delay between flow pulses measured from the root of the aorta and the popliteal artery, and systemic vascular resistance was calculated from cardiac output and mean arterial pressure. In addition, a progressive maximal exercise test was performed after the treatments. RESULTS: Propranolol reduced heart rate, cardiac output and arterial pulse wave velocity, and increased systemic vascular resistance clearly more effectively than placebo. In addition, captopril effectively decreased arterial resistance and pulse wave velocity. However, the influence of verapamil on cardiovascular parameters did not significantly differ from those observed in placebo-treated subjects. Exercise peak heart rate, peak blood pressure, and minute ventilation were reduced in subjects treated with propranolol, but not in those treated with captopril and verapamil, when compared to placebo. CONCLUSIONS: Acute administration of captopril and propranolol but not verapamil clearly modulated cardiovascular parameters in rest, suggesting differential effects of these compounds on cardiovascular function in healthy volunteers. These drugs seem to have disparate effects on arterial pulse wave propagation as an indicator of arterial compliance after short-term administration in healthy subjects. Captopril and verapamil had no effect on cardiovascular and ventilatory function during maximal exercise, while propranolol markedly altered also these variables in the present study.

Transformation of bisphosphonates into insoluble material in human blood in vitro.

The aim of the study was to find out whether bisphosphonates transform into insoluble material in human blood and serum in vitro. Samples of fresh blood and serum were incubated with various concentrations of 14C-labelled clodronate, etidronate, pamidronate and tiludronate for 2 h and 8 h at 37 degrees C. The presence of unfiltrable material in the plasma separated from the blood, and in the serum were studied with 1) 100, 300 and 1,000 kd (kilo Daltons) filter tubes centrifuged at 3,000 g for 60 min, and 2) high-speed centrifugation at 13,000 g for 30 min. The radioactivities in the ultrafiltrates and supernatants were compared to those in the native plasma or serum. All bisphosphonates transformed into unfiltrable material, which was separated from the samples with the 100 and 300 kd filters but not with the 1,000 kd filter. The material was not sedimented with the high-speed centrifugation. The lengthening of the incubation time from 2 h to 8 h increased the unfiltrable fraction, which generally was dependent on the drug concentration in the blood, too. However, the fraction of the unfiltrable material did not seem to increase with time when the drug was incubated with serum instead of blood. Since drug binding to plasma proteins is generally a very rapid process, some factors other than proteins only, e.g. cations or cation residues, present in the blood but not in the serum, should be involved in transforming of bisphosphonates into insoluble material in the blood.

Effects of liposome-encapsulated bisphosphonates on acetylated LDL metabolism, lipid accumulation and viability of phagocyting cells.

Bisphosphonates, the drugs used for the treatment of e.g. osteoporosis, inhibit the development of experimental atherosclerosis. When encapsulated in liposomes, they also inactivate macrophages, which have a key role in atherogenesis. We studied the effects of three clinically used bisphosphonates, i.e. clodronate, etidronate and pamidronate, on 1) the viability of mouse peritoneal macrophages and macrophage-like RAW 264 cells, 2) the degradation of 125I-labeled acetylated LDL by RAW 264 cells, and 3) the formation of LDL-derived foam cells in vitro. Liposome-encapsulated clodronate and pamidronate, but not etidronate, decreased the fraction of viable peritoneal macrophages in a concentration-dependent manner, whereas RAW 264 cells were much more resistant to the cytotoxic effects of bisphosphonates. Preincubation with liposomal clodronate and etidronate inhibited in a concentration-dependent manner the degradation of acetylated LDL in RAW 264 cells, but non-cytotoxic concentrations of liposomal pamidronate had only a weak inhibitory effect. The inhibition was more pronounced by liposomal clodronate than by liposomal etidronate. At high concentrations (500 microg protein/ml) of acetylated and aggregated LDL, RAW 264 cells transformed to foam cells. Preincubation with liposomal clodronate and etidronate reduced the cellular accumulation of acetylated LDL-derived lipids, but the drugs had no effect on the lipid accumulation caused by aggregated LDL. The results suggest that liposomal clodronate and etidronate inhibit the activity of phagocyting cells in internalizing and degrading atherogenic modified LDL.

Accumulation of bisphosphonates in the aorta and some other tissues of healthy and atherosclerotic rabbits.

Clodronate, etidronate, and pamidronate are highly hydrophilic bisphosphonates used for the treatment of bone resorption and hypercalcemia. They also inhibit the development of experimental atherosclerosis without influencing serum cholesterol level. We studied the distribution and the accumulation of the carbon 14-labeled bisphosphonates in the aorta and some other tissues of healthy rabbits and in rabbits with diet-induced atherosclerosis. After intravenous injection, clodronate and pamidronate disappeared from circulation more slowly in atherosclerotic than in healthy rabbits, and the drug concentrations in the peripheral tissues were generally lower in atherosclerotic than in healthy animals. At 24 hours after dosing in healthy rabbits, the mean aorta to plasma ratios of clodronate, etidronate, and pamidronate were, respectively, 2.4 to 2.8, 2.4 to 4.0, and 8.6 to 10. The corresponding ratios in atherosclerotic rabbits were, respectively, 13 to 22, 1.5 to 2.2, and 13 to 24. Seven days after the injection the mean clodronate concentration in the aortas of healthy rabbits was 0.5% to 0.9% of the dose given per tissue weight, and the concentration in those of atherosclerotic animals was 3.8% to 5.2% of the dose given per tissue weight. The results indicate that hydrophilic bisphosphonates, known to inhibit the atherogenesis, concentrate markedly in the aortas of healthy and atherosclerotic rabbits.

Effects of clodronate (dichloromethylene bisphosphonate) on the development of experimental atherosclerosis in rabbits.

The effects of clodronate, a bisphosphonate for the treatment of hypercalcemia, on the progress of atherosclerosis were studied in rabbits fed with a high-cholesterol (1%) diet and treated simultaneously with disodium clodronate 0 (saline), 1, 5, or 25 mg/kg intravenously twice a week for 6, 9, and 12 weeks. In 9 to 12 weeks, plasma total cholesterol increased from 0.8 +/- 0.3 mmol/L (mean +/- SD) in rabbits fed the standard diet to 46 +/- 17 mmol/L in animals subjected to high-cholesterol diet. Clodronate did not influence the cholesterol concentration in plasma. None of the parameters studied were changed by clodronate within 6 weeks after beginning the treatment. In 9 to 12 weeks (n = 7 to 9), plasma total Ca++ concentration was decreased from 3.55 +/- 0.12 mmol/L in the saline group to 3.36 +/- 0.16 mmol/L in the group on the greatest clodronate dose (p < 0.05). Free and esterified cholesterol and total Ca++ concentrations in the wall of thoracic aorta were reduced by the greatest dose of clodronate, compared with the groups treated with saline solution or smaller doses of the drug (p < 0.05). At 12 weeks, the greatest dose of clodronate also reduced the visible and lipid-stained atheromatous areas in the thoracic and abdominal aorta, compared with those in the saline and the other clodronate dose groups (p < 0.05). The results suggest that a high dose of clodronate inhibits the development of diet-induced atherosclerosis in rabbits.