Non-small cell lung cancer patients with EML4-ALK fusion gene are insensitive to cytotoxic chemotherapy

BACKGROUND

Although patients with the echinoderm microtubule-associated protein-like 4-anaplastic lymphoma kinase gene (EML4-ALK) re-arrangement and epidermal growth factor gene EGFR mutations have proven sensitive to specific inhibitors, there is currently no consensus regarding the sensitivity of non-small cell lung cancer (NSCLC) patients with such mutations to cytotoxic chemotherapy.

PATIENTS AND METHODS

The responses to first-line cytotoxic chemotherapy were retrospectively compared between advanced or postoperative recurrent patients with non-squamous NSCLC who harbor the EML4-ALK fusion gene (ALK+), EGFR mutation (EGFR+), or neither abnormality (wild-type).

RESULTS

Data for 22 ALK+, 30 EGFR+, and 60 wild-type patients were analyzed. The ALK+ group had a significantly lower response rate than the other two groups. Progression-free survival was significantly shorter in the ALK+ cohort compared to the EGFR+ (p<0.001) and wild-type cohorts (p=0.0121).

CONCLUSION

NSCLC patients with the EML4-ALK fusion gene might be relatively insensitivite to cytotoxic chemotherapy.

Impact of the epidermal growth factor receptor mutation status on the post-recurrence survival of patients with surgically resected non-small-cell lung cancer

OBJECTIVES

The impact of epidermal growth factor receptor (EGFR) status and the use of EGFR-tyrosine kinase inhibitor (EGFR-TKI) therapy have not been well discussed only in recurrent non-small-cell lung cancer (NSCLC). The purpose of this study was to identify the prognostic factors associated with post-recurrence survival after surgical resection of NSCLC in terms of the EGFR mutation status and the use of EGFR-TKI therapy.

METHODS

From 2000 through 2011, 1237 consecutive patients with NSCLC underwent pulmonary resection at our institution. Of these patients, 280 experienced postoperative recurrence by the end of 2012. We reviewed the cases of recurrence and analysed the predictors and length of post-recurrence survival.

RESULTS

The median post-recurrence survival time and the 5-year survival rate of all patients were 25 months and 20.8%, respectively. A multivariate analysis identified the Eastern Cooperative Oncology Group (ECOG) performance status (PS), brain metastasis, number of sites of recurrence and EGFR mutation status to be independent prognostic factors for post-recurrence survival. Among all cases, the median post-recurrence survival time according to the use of EGFR-TKI therapy was as follows: 49 months in the EGFR mutation-positive patients treated with EGFR-TKI therapy, 20 months in the EGFR wild or unknown cases treated with EGFR-TKI therapy and 17 months in the patients not treated with EGFR-TKI therapy. As to EGFR mutation-positive cases, the patients treated with EGFR-TKIs exhibited significantly longer post-recurrence survival time than the patients treated without EGFR-TKIs (49 vs 12 months).

CONCLUSIONS

It is essential for recurrent NSCLC patients to be examined for the EGFR mutation status. Patients with a positive EGFR mutation status receive significant benefits from EGFR-TKI therapy.

Gemcitabine and vinorelbine as second-line or beyond treatment in patients with malignant pleural mesothelioma pretreated with platinum plus pemetrexed chemotherapy

BACKGROUND

Malignant pleural mesothelioma (MPM) is an aggressive neoplasm that responds poorly to chemotherapy. Although treatment with pemetrexed in combination with cisplatin serves as first-line chemotherapy for MPM, the optimal second-line and beyond therapy has not yet been fully examined.

METHODS

Between March 2008 and October 2011, 17 consecutive Japanese patients pretreated with at least one regimen of platinum plus pemetrexed chemotherapy received gemcitabine and vinorelbine. Responses, survival time, and toxicity were retrospectively evaluated.

RESULTS

Response [partial response (PR) + complete response (CR)] and disease control [stable disease (SD) + PR + CR] rates were 18 and 82 %, respectively. The median progression-free survival (PFS) after combination chemotherapy was 6.0 months, whereas the median overall survival (OS) was 11.2 months. Grade 3 or 4 neutropenia and anemia were observed in 41 and 29 % of patients, respectively, and one patient experienced febrile neutropenia. Grade 3 or 4 nonhematologic toxicities included constipation (6 %) and phlebitis (6 %).

CONCLUSION

Combination chemotherapy using gemcitabine with vinorelbine was shown to have moderate activity in Japanese MPM patients pretreated with platinum plus pemetrexed chemotherapy. A further multicenter phase II trial is warranted to confirm the efficacy and safety of this combination treatment.

Amrubicin as second-line and beyond treatment for platinum-refractory advanced thymic carcinoma

OBJECTIVE

Thymic carcinoma is a rare mediastinal neoplasm, and the prognosis of patients with advanced thymic carcinoma is poor. No standard chemotherapeutic regimen has yet been established for the disease. This is the first report to evaluate the role of amrubicin, a novel anthracycline anticancer drug, in second-line and beyond treatment for patients with platinum-refractory advanced thymic carcinoma.

METHODS

This study was a review of thymic carcinoma patients who had received amrubicin monotherapy between June 2003 and December 2011 for the progression of disease previously treated with platinum-based chemotherapy. Amrubicin was administered at 35 or 40 mg/m(2) for three consecutive days every 3 weeks, until progression.

RESULTS

Nine patients with recurrent thymic carcinoma were registered. Their median age was 61 years (range 45-72), and the patients included five males and four females. All nine patients had Masaoka's Stage IVb disease. There were three squamous cell carcinomas, one adenocarcinoma, one small-cell carcinoma and two other histological types. The mean number of chemotherapy cycles was five (range 2-13). Grade 3 or higher toxicities included mainly neutropenia (55.5%), anemia (25.0%) and febrile neutropenia (11.1%). No treatment-related deaths were observed. The response rate was 44.4% (95% confidence interval: 19-73). The median progression-free survival after the amrubicin monotherapy was 4.9 months, while the median overall survival was 6.4 months.

CONCLUSIONS

Single-agent amrubicin was found to be potentially useful as second-line and beyond chemotherapy for patients with advanced thymic carcinoma. Further multi-institutional prospective studies are warranted.

Recurrence of thymic neuroendocrine carcinoma 24 years after total excision: A case report

A 77-year-old male presented with chest pain in March 2012. The individual had undergone surgery for an anterior mediastinal tumor 24 years earlier and the pathological diagnosis was that of a thymoma. The patient underwent a medical check-up every 6 months for the next 20 years. However, ∼3 years following the final check-up, sudden chest pain was reported and the patient was referred again. Computed axial tomography revealed a mediastinal mass adjacent to the left lung, pericardium and sternum. There was no apparent invasion to the adjacent structures. The patient underwent surgical resection following a diagnosis of recurrent thymoma. A posterolateral thoracotomy was performed under video-assisted thoracoscopy. Severe adhesions were observed around the tumor, which appeared to invade the left lung and pericardium, but not the chest wall. The tumor was extirpated in combination with partial resection of the left lung and pericardium. The pathological diagnosis of the tumor was of a well-differentiated neuroendocrine carcinoma (NEC) of the thymus. The specimen that was excised 24 years earlier was re-examined by a pathologist and was reported to exhibit the same histology. Primary NECs of the thymus are rare among anterior mediastinal tumors and the 5-year survival rate is ∼30%. The present case study reports a case of a thymic NEC and describes the pathological and clinical features.

[A case of imatinib-resistant GIST treated by sunitinib]

We report a case of imatinib-resistant GIST, successfully treated by sunitinib. A 62-year-old man with high-grade fever and a huge abdominal tumor was diagnosed with malignant GIST and multiple liver metastases. We performed total gastrectomy combined with distal pancreatectomy, and splenectomy for palliation. Imatinib at a dose of 300mg/day was administered postoperatively, and the liver metastases was well controlled. After nine months, abdominal dissemination increased, and we raised the dose of imatinib to 400mg/day for the progressive state. Subsequently, we had to discontinue imatinib due to its adverse effects. Because the tumors progressed greatly while imatinib was discontinued, we changed to sunitinib. After wards, tumors reduced and his general condition improved remarkably. Although tumors progressed after five months, he was able to obtain good QOL during the administration of sunitinib. Sunitinib is useful for imatinib-resistant GIST, and may be a promising treatment even for patients with poor PS.

Persistent and Aggressive Treatment for Thymic Carcinoma

OBJECTIVES

The aim of this study is to retrospectively evaluate the role of several therapies, mainly chemotherapy, for thymic carcinoma (TC).

METHODS

From July 1973 to July 2005, 25 patients (15 males and 10 females) with histologically proven TC were treated at our department. The median age of the patients was 59 years, with a range of from 30 to 78 years. According to Masaoka's staging system, there was 1 stage I patient, 3 stage II, 7 stage III, 6 stage IVa, and 8 stage IVb patients. The histological subtype was in all cases squamous cell carcinoma, nonkeratinizing type.

RESULTS

There were 6 complete surgical resections, 1 incomplete resection followed by chemoradiotherapy, 6 with radiotherapy alone, 3 with radiotherapy plus chemotherapy, and 9 with chemotherapy alone as the initial treatment. Eighteen patients were administered second-line therapy. The regimen obtaining the best response rate was doublet chemotherapy consisting of carboplatin (CBDCA) and paclitaxel. The median survival time and survival rate at 5 years for the patients excluding surgical cases with stage I/II disease were 32 months and 31%, respectively.

CONCLUSION

The doublet of CBDCA and paclitaxel thus appears to be a promising regimen for TC and further investigation in a multi-institutional phase II trial is, therefore, strongly called for.

Establishment of a clinical pathway as an effective tool to reduce hospitalization and charges after video-assisted thoracoscopic pulmonary resection

OBJECTIVE

The purpose of this study was to assess the effect of establishing a clinical pathway based on the length of hospitalization, hospital charges, and the outcome for video-assisted thoracoscopic pulmonary resection (VATPR).

METHODS

We retrospectively analyzed consecutive patients who were diagnosed as having primary lung cancer, metastatic lung cancer, or a nodule that was suspected to be malignant and thus was operated on using VATPR during the 1-year period before (n = 105) and after (n = 113) pathway implementation.

RESULTS

The mean economic cost and total hospital stay before and after pathway implementation were about dollars 14439 and dollars 13093 (US), and 29.4 and 18.6 days, respectively. These figures were significantly lower after pathway implementation than before establishment of the pathway.

CONCLUSION

A clinical pathway is thus considered useful for reducing the length of total hospital stay and the costs associated with VATPR while maintaining high-quality postoperative care.

Prognostic value of the histological subtype in completely resected non-small cell lung cancer

Non-small cell lung cancer (NSCLC), which includes several different histological subtypes, is usually treated by the same strategy. However, the biological behavior of each cell type appears to be different. We retrospectively reviewed the clinical records of 1119 consecutive NSCLC patients who underwent a complete resection, in order to investigate whether a histological cell type is a powerful prognostic factor. The overall 5- and 10-year survivals of the patients with adenocarcinoma (AD), squamous cell carcinoma (SQ), large cell carcinoma (LA), and adenosquamous cell carcinoma (AS) were 54.2 and 40.2%, 51.6 and 30.3%, 40.9 and 18.7%, and 35.1 and 30.1%, respectively. The AD patients had a significantly better survival than the non-AD patients in Stage I (P=0.0004), whereas the SQ patients had a better survival than the non-SQ patients in Stage II (P=0.018). A multivariate survival analysis indicated the AD patients to have a significantly better survival than the SQ patients in Stage IA (P=0.04), while the SQ patients had a better survival than the AD patients in Stage II (P=0.03). These above observations suggest that the prognosis after complete resection is different between adenocarcinoma and squamous cell carcinoma in Stage IA and II.

Reduction of carotid artery blood flow in pediatric patients with syncope: evaluation with head-up tilt test

We investigated the effect of postural changes on cerebral circulation by measuring carotid artery blood flow (CABF) in the supine position and during head-up tilt (HUT) test using a Doppler flow meter. Subjects included 10 patients with neurally mediated syncope, 10 patients with orthostatic intolerance, 8 with epilepsy, aged between 8 to 24 years (mean +/- SD, 13.9 +/- 4.1 years). The test caused pallor and dizziness in 16 patients (symptomatic), while no symptoms were recognized in the other 12 patients (asymptomatic). Significant reductions in the mean CABF (Fm), maximum CABF (Fs) and minimum CABF (Fd), components of the CABF waveform, were noticed during HUT compared to before HUT (supine), and these reductions in symptomatic patients were more severe than those in asymptomatic patients (Fm: - 2.8 +/- 2.0 SD vs - 0.7 +/- 1.4 SD; Fs: - 2.7 +/- 1.5 SD vs - 0.9 +/- 1.3 SD; Fd: - 4.5 +/- 2.8 SD vs - 2.2 +/- 2.1 SD). Reductions in Fm, Fs and Fd in the symptomatic patients during HUT lasted longer than those of the asymptomatic patients, being statistically significant for Fm and Fs (Fm: p < 0.01; Fs: p < 0.05). The criteria during HUT for distinguishing neurally mediated syncope (NMS) from others was Fs: < - 4 SD and Fd: < - 5 SD. Our data suggest that reduction of CABF should be carefully evaluated for the diagnosis of neurally mediated syncope in pediatric patients. Such a reduction might be an essential mechanism of syncopal attacks.

Reduction of carotid arterial blood flow in ventricular septal defect associated with severe congestive heart failure

After diagnosing abnormality of cardiac and carotid-cerebral circulation in an infant with isolated ventricular septal defect (VSD) associated with severe congestive heart failure, the authors measured the carotid arterial blood flow volume (CABF). At 3 months, the patient was not thriving and had dyspnea because of severe congestive heart failure. The authors measured the VSD size/body surface area (BSA) ratio relative to the predicted value of the left ventricular end-diastolic dimension (%LVEDd), left-to-right shunt ratio (Qp/Qs), and the small stroke volume (SV)/BSA using echocardiography and cardiac catheterization. The mean, maximum, and minimum CABF (mean CABF, maxCABF, and minCABF) among R-R intervals on electrocardiogram were measured by Doppler flowmetry in this patient and 5 healthy age-matched control children. The patient had a large VSD size/BSA ratio (37.9 mm/m2), %LVEDd (164%), and Qp/Qs (3.8), and a small SV/BSA ratio (18 mL/m2). The mean CABF, maxCABF, and minCABF were significantly lower than those of control children (VSD patient vs. controls; 2.7 +/- 0.4 vs. 4.5 +/- 0.6, 6.1 +/- 0.9 vs. 12.0 +/- 2.1, 1.2 +/- 0.2 vs. 1.7 +/- 0.4 mL/sec (mean +/- S.D.)), respectively (p < 0.01). The authors' results showed abnormal cardiac and carotid-cerebral circulation in an infant with large VSD associated with severe congestive heart failure.

Two-dimensional autoregressive analysis of carotid artery blood flow waveform in children with isolated atrial septal defect

BACKGROUND

The aim of the present study was to analyze the carotid artery blood flow waveform, using a two-dimensional autoregressive modeling approach and component analysis, and to determine the relation between cardiac contractility, peripheral and cerebral circulation and characteristic values of component activities of carotid artery blood flow waveform in patients with atrial septal defect (ASD), with or without congestive heart failure.

METHODS AND RESULTS

We analyzed the carotid artery blood flow waveform of nine patients with ASD and 35 normal controls using a two-dimensional autoregressive modeling approach. The component of impulse response was divided into six groups according to the damping frequency: (i) group I, 0 Hz; (ii) group II, 1-5 Hz; (iii) group III, 5-8 Hz; (iv) group IV, 8-13 Hz; (v) group V, 13-17 Hz and (vi) group VI, > 17 Hz. The decrease of impulse response power-density in patients of groups I, II, III and IV and the prolongation of damping time for patients in groups I and II were particularly noticeable in two ASD patients, whose pulmonary to systemic blood flow ratio was more than 2.7 and whose left ventricular stroke volume was less than 33.1 mL/m2. The power-density of groups I and II varied with cardiac contractility and the power-density of groups III and IV varied with cerebral circulation. In contrast, the damping time of groups I and II changed with the reflection velocity from the position of arterial reflection against blood flow from left ventricle.

CONCLUSIONS

These results may be influenced by the decrease in left ventricular stroke volume and velocity in arterial reflection.

Normal developmental changes in carotid artery diameter measured by echo-tracking

We examined the developmental changes in carotid arterial diameter and its change with pulsatile pressure in infants and children using the phase-locked echo-tracking method. The mean, maximum systolic, and minimum diastolic carotid arterial diameter and pulsating diameter changes were measured in 95 healthy children aged 1 month to 13 years. The mean, maximum, and minimum carotid arterial diameter increase significantly and exponentially with age, body weight, height, and body surface area, and the correlation coefficient was highest with body surface area. The change in carotid arterial diameter with pulse pressure increased gradually until 2 to 3 years of age. Our results suggest that the maturational changes in carotid diameter and the dynamic changes in the diameter reflect changes in the carotid-cerebral circulatory system. The noninvasive measurement of the carotid diameter and pulsating diameter changes by a phase-locked echo-tracking method is useful for examining carotid-cerebral circulatory disorders.

Mutations induced in Drosophila during space flight

To examine the possible effects of space radiation on living organisms, fruit flies Drosophila melanogaster were loaded on the US Space Shuttle Endeavour, and after the flight we have analyzed two types of mutations, sex-linked recessive lethal mutations induced in male reproductive cells and somatic mutations which give rise to morphological changes in hairs growing on the surface of wing epidermal cells. Wild type strains and a radiation-sensitive strain mei-41 were used. The frequencies of sex-linked recessive lethal mutations in flight groups were 2 and 3 times higher for wild type Canton-S and mei-41 strains, respectively, than those in ground control groups. By contrast, the frequencies of wing-hair somatic mutations differed little between flight and control groups. The possibility that the space environment causes mutations in certain types of cells such as male reproductive cells, is discussed.

[Estimation of SIDS with measurement of cardio-respiratory contribution ratio through multivariate autoregressive modelling approach]

We obtained the cardio-respiratory impulse response and noise contribution ratio to study the central respiratory control system in one case of Ondine's curse, one case of sleep apnea syndrome and 34 cases of preterm infants, using multivariate autoregressive analysis. In Ondine's curse, the noise contribution ratio decreased during sleep. In the sleep apnea syndrome, the noise contribution ratio before apnea and after apnea decreased. In the preterm infants, the noise contribution ratio increased with the conceptional age. From these results, we concluded that the central cardio-respiratory control system was disturbed in Ondine's curse, sleep apnea syndrome and preterm infants. The cardio-respiratory impulse response using a multiple autoregressive analysis was useful for prediction of sudden infant death syndrome.

Normal developmental changes in carotid arterial blood flow measured by Doppler flowmetry in children

We examined the developmental changes in carotid arterial blood flow in a group of neonates, infants, and children using a Doppler flowmeter. The mean, maximum and minimum carotid arterial blood flow (CABF) were measured serially in 35 healthy newborns during the first 5 days of life (total 175 records), and in 62 healthy children aged 1 month to 13 years. In newborns, the mean CABF increased significantly on the second day of life, while the maximum and minimum CABFs increased significantly every day during the first 3 days of life. The mean, maximum, and minimum CABFs increased steadily and significantly in those older than 1 month but reached a plateau after 2 to 4 years of age. Our results indicate that CABF changes with age in early life, reflecting a change in cardiac contraction and carotid-cerebral circulatory system. The measurement of CABF by Doppler flowmetry may be useful for examining cardiac and carotid-cerebral circulatory disorder.

Developmental change in carotid artery blood flow waveform by component analysis in children

The carotid artery blood flow waveform (CABFW) is regarded as a summation of cardiac impulse responses. These impulse responses are divided into several components through a two-dimensional autoregressive modelling approach. Using this approach, we determined the developmental change in CABFW in 94 normal subjects from the neonatal period to adolescence. Our analysis demonstrated that: (i) the total power of impulse response increased significantly with increasing age. The component of impulse response was divided into six groups according to the damping frequency: group I (0 Hz), group II (1-5 Hz), group III (5-8 Hz), group IV (8-13 Hz), group V (13-17 Hz) and group VI (> 17 Hz); (ii) the power-density and the damping time of group I and II impulse response increased significantly with increasing age; (iii) the power-density and percent power of group III impulse response and power-density of group IV impulse response increased significantly with increasing age. Our results indicated that CABFW contained some regular impulses and that group I, II, III and IV, which were influenced by several factors, including cardiac contraction and the compliance and frictional forces of the carotid artery, appeared to be important to the developmental change of CABFW in children.

Multivariate autoregressive analysis of carotid artery blood flow waveform in an infant of a diabetic mother with cardiomyopathy

We analyzed the carotid artery blood flow waveform (CABFW) of an infant of a non-insulin dependent diabetic mother with hypertrophic cardiomyopathy (IDM cardiomyopathy) through multivariate autoregressive analysis and compared the developmental change of his CABFW with that of normal newborns. The total power was lower than normal newborns on the second and third day of life when his heart dysfunction was severe, and elevated on the fifth day of life when normal-heart function was recovered. The power of component 3 (C3), of which the damping frequency was 7-11 Hz, was slightly high on the second and third day of life and it decreased to the normal range on the fifth day of life by component analysis. In contrast, the power of C3 increased with decreasing resistance index of anterior cerebral artery (RI of ACA) which shows the cerebral vascular resistance of normal newborns. These results suggest that the carotid artery blood flow volume decreased by low cardiac output and the cerebral vascular resistance decreased to maintain the cerebral circulation, when the heart dysfunction was severe.

[Multivariate autoregressive analysis of carotid artery blood flow waveform in a newborn with multicystic encephalomalacia]

We analyzed the carotid artery blood flow waveform (CABFW) through multivariate autoregressive analysis in a case with multicystic encephalomalacia (MCE) after neonatal asphyxia and compared the result with those of 35 healthy newborns. The total power of CABFW was at the -2 SD level of the value for 35 healthy newborns, and the power, % power, bio-informing amounts and damping time of component 3 (damping frequency 11.15 Hz) were less than -2 SD of the values in 35 healthy newborns. The Pulsatility Index (PI) of anterior cerebral artery (ACA) was high (0.76). These results suggest that cerebral blood flow decreases because of cerebral vasoconstriction in MCE after neonatal asphyxia.

[An experience with surgical treatment for mucoepidermoid carcinoma of the lungs]

Mucoepidermoid carcinoma (MEC) of the lungs is thought to arise in the bronchial glands. It is a tumor that rarely develops and it has a low grade of malignancy. In this paper, we describe one case of infiltrative MEC, which we were able to diagnose preoperatively. Surgery revealed a high grade malignancy which is reported here with a discussion based on the related literature. The patient was a 63-year-old male who was referred to our hospital by another physician due to a cough and left chest pain. A simple chest X-ray revealed a tumor shadow and a fascicular shadow on its periphery in the upper left lobe. Bronchoscopy disclosed complete circumferential stenosis at B1+2,3 and reddening from this region to the main bronchus, but it was impossible to directly confirm the tumor. Pulmonary arterography did not depict the left upper pulmonary vein, but obstruction due to a tumor of that vein was observed. Given the above findings, under a diagnosis of infiltrative MEC, a left total lobectomy accompanied by a combined left atriectomy was performed. Although most cases of MEC have a low grade malignancy, there have been some reported cases with a very high grade of malignancy. Therefore, evaluation of the progress of this type of carcinoma by preoperative diagnosis as well as radical excision appropriate to lung cancer are considered to be important.

Cardio-respiratory control in an infant with Ondine's curse: a multivariate autoregressive modelling approach

We applied spectral analysis through multivariant autoregressive model fitting [1] to RR interval (RRI) and respiratory (RES) oscillation obtained during quiet sleep in an infant with congenital central hypoventilation syndrome (Ondine's curse), a child with obstructive sleep apnea, and two healthy children. Power spectra, impulse response and noise contribution ratio between RRI and RES oscillation were calculated by using a minicomputer PFU-1200 (FACOM) to determine the structure of the feedback system between RRI and RES within the central nervous system. We found that the respiratory noise contribution ratio to RRI was significantly smaller in Ondine's curse (37 +/- 7.7%, at 0.23 Hz) than in obstructive sleep apnea (90 +/- 6.7%, at 0.39 Hz) and healthy subjects. We postulate that the result shows disturbance of the central autonomic control of breathing and heart rate in Ondine's curse.

The inhibitory effects of cimetidine on elimination and distribution of propranolol in rats

We studied the effects of cimetidine on the pharmacokinetics, blood and tissue distribution and plasma protein binding of propranolol in rats. The plasma disappearance of propranolol after a 10 mg/kg intravenous injection and oral administration were fitted to a two compartment open model. In the cimetidine treated rats, the area under concentration curve after an intravenous injection (AUCiv) was increased by 64% and the plasma total body clearance (Cltot) and the rate constant at the terminal phase (beta) were decreased by 38% and 33% of those of the non-treated rats, respectively. The area under the concentration curve after oral administration (AUCpo) was increased by 62% and the plasma oral clearance (Clpo) was decreased by 39% by cimetidine treatment, whereas the bioavailability (F) was not changed. The hepatic blood flow rate (Qh) and the product of the plasma unbound fraction and the hepatic intrinsic clearance (fp x Clint,h) calculated from Cltot and Clpo were decreased by 30% and 39%, respectively. The blood-to-plasma concentration ratio (Rb) and the tissue-to-plasma concentration ratio (Kp) of propranolol were not affected by cimetidine treatment, while the binding constant (Kb) in plasma was decreased by 45%. The plasma unbound fractions (fp) of propranolol were increased by 25-70% in the in vivo plasma concentration range (0.1-1.0 microgram/ml) resulting in the decrease of tissue-to-plasma unbound concentration ratio (Kp,u) in lung, heart, spleen, brain and muscle. Cimetidine was shown to have the inhibitory effects on elimination and distribution of propranolol in rats.