Correlation between the transdermal characteristics of pseudoephedrine and amygdalin in majiepingchuan in vitro.

OBJECTIVE: To analyze the transdermal profile of pseudoephedrine and amygdalin in the Traditional Chinese Medicine majiepingchuan in rat skin and to reveal their interaction. METHODS: A Franz diffusion cell was used in vitro to evaluate the transdermal parameters of cumulative transdermal flux (Q(tot)), cumulative transmission (T(tot)), and mean penetration rate (Kp) of pseudoephedrine and amygdalin in majiepingchuan. Linear regression analyses of Q(tot) over time of pseudoephedrine vs amygdalin and their ratios was adopted for correlation evaluation. RESULTS: At 1, 2, 4, 6, and 8 h, the Q(tot), T(tot) and Kp of pseudoephedrine showed a good correlation with that of amygdalin. CONCLUSION: There was a small difference in the ratios of Q(tot), T(tot) and Kp between pseudoephedrine and amygdalin, and a correlation between them.

Survey of Physicians and Healers Using Amygdalin to Treat Cancer Patients.

Amygdalin is purported to exhibit anti-cancer properties when hydrolyzed to hydrogen cyanide (HCN). However, knowledge about amygdalin efficacy is limited. A questionnaire evaluating the efficacy, treatment, and dosing protocols, reasons for use, HCN levels, and toxicity was distributed to physicians and healers in Germany, providing amygdalin as an anti-cancer drug. Physicians (20) and healers (18) provided amygdalin over 8 (average) years to nearly 80 annually treated patients/providers. Information about amygdalin was predominantly obtained from colleagues (55%). Amygdalin was administered both intravenously (100%) and orally (32%). Intravenous application was considered to maximally delay disease progression (90%) and relieve symptoms (55%). Dosing was based on recommendations from colleagues (71%) or personal experience (47%). If limited success became apparent after an initial 3g/infusion, infusions were increased to 27g/infusion. Treatment response was primarily monitored with established (26%) and non-established tumor markers (19%). 90% did not monitor HCN levels. Negative effects were restricted to a few dizzy spells and nausea. Only 58% were willing to participate in clinical trials or contribute data for analysis (34%). Amygdalin infusions are commonly administered by healers and physicians with few side effects. The absence of standardized treatment calls for guidelines. Since intravenous application bypasses metabolization, re-evaluation of its mode of action is required.

Formation of amygdalin/ß-cyclodextrin derivatives inclusion complexes for anticancer activity assessment in human cervical carcinoma HeLa cell line.

Nanoencapsulation has gained considerable attention because of its unique features and advantages in anticancer drug delivery. Amygdalin (AMY) is an anticancer compound, showing limitations in its applications by low stability. Herein, the inclusion complexes (ICs) of AMY with ß-cyclodextrin (ßCD), and its derivatives such as 2-hydroxypropyl-ßCD (HPßCD) and methyl-ßCD (MßCD) were fabricated. The fabricated AMY/CD-ICs were thoroughly evaluated using Fourier-transform infrared spectroscopy, powder X-ray diffraction, thermogravimetric/differential thermal analysis, proton nuclear magnetic resonance, ultraviolet-visible diffuse reflectance spectroscopy, and photoluminescence techniques. Double reciprocal profile study of the absorption and fluorescence spectra revealed that the AMY formed the ICs with ßCD derivatives at a guest/host stoichiometric ratio of 1/1. The thermal stability of AMY was enhanced as the IC formation aid observed by the shift of thermal degradation temperature of AMY from the range of âˆ¼ 220-250 °C to > 295 °C. Theoretical analyses of the energetic, electronic, and global reactivity parameters of the AMY/CD-ICs were evaluated using the PM3 method. Further assessment of the dissolution diagrams of AMY/CD-ICs revealed a burst release profile. In addition, cell toxicity was evaluated using the MTT assay, and the results showed that AMY/CD-ICs had significantly more efficacious in inhibiting HeLa cancer cells than AMY. These results proved that the IC formations with CDs significantly enhanced the anticancer activity of AMY.

[Alternative means of drug therapy in cancer: letril].

Letril (amygdaline) is one of drugs of alternative therapy for cancer that is used over three decades and relates to cyanogenic glycosides received from kernels of various fruits (almonds, apricots, peaches, etc. The basis of suggestion of letril as antitumor agent is hypotheses about selective fermentative splitting of amygdaline in tumor cells with developing of cyanide that should cause to apoptosis as a result of aerobic glycolysis suppression. None of these assumptions found their experimental confirmation. In clinical trials there was established inefficiency of letril with a very high probability to develop severe cyanide intoxication. Despite obtained scientific data and absence of permission from the supervising institutions (FDA) letril is still advertised, produced and distributed as anti-tumor drug.

[Uniform designed research on the active ingredients assembling of Chinese medicine prescription for anti-liver fibrosis].

OBJECTIVE: To explore the method and significance for studying active anti-liver fibrosis ingredients consisted Chinese medicine compound prescription based on Chinese medicine theory. METHODS: Optimized prescription was screened out, adopting uniform block design with 4-factor 8-level table and regression analysis, through applying the four known effective ingredients (cordyceps sinensis polysaccharide, salvianolic acid B, amygdaloside and gypenosides) of Fuzheng Huayu Capsule (FZHYC, a new Chinese medine anti-liver fibrosis drug) to two rat liver fibrosis models established separately by dimethylnitrosamine (DMN) and CCl4, and taking the liver content of hydroxyproline (Hyp) as the screen index. Then a further study for comparing and verifying the efficacy of the obtained optimized prescription was conducted on the two former models respectively by observing the changes of Hyp content in liver, serum ALT activity and fibrosis pathology after medication, controlled by the original FZHYC and the recipe assembled by all the four ingredients. RESULTS: Two optimized prescriptions (OPA and OPB) were screened out separately in the studies conducted on the two models. Both of them were consisted of cordyceps sinensis polysaccharide, Amygdaloside and Gypenosides, but different in constituent ratio, i.e., the ratio in OPA was 60 : 80: 50, and that in OPB, 20: 160: 50. Verifying study showed both OPA and OPA were significantly effective, with the efficacy equivalent to that of FZHYC (P>0.05). However, when they were used in combining with salvianolic acid B (the cutout ingredient in the screening), the efficacy lowered surely. CONCLUSIONS: Uniform design is a valuable method in the compatibility research of Chinese Medicine drugs' composition. To assemble a new compound recipe reasonably based on the prescription of traditional compound recipe could make its effect equivalent to that of the original prescription. Ingredients or constituents in a prescription, either presented synergistic or antagonistic effects, are not randomly stacked together, and they should be orderly assembled in intrinsic rules of qualitative and quantitative changing.

Congenital malformations induced by laetrile.

Laetrile administered orally ot pregnant hamsters caused skeletal malformations in the offspring, but intravenous laetrile filed to result in embryopathic effects. Oral laetrile significantly increased in situ cyanide concentrations, while intravenous laetrile did not. Thiosulfate administration protected embryos from the teratogenic effects of oral laetrile. The embryopathic effects of oral laetrile appear to be due to cyanide released by bacterial beta-glucosidase activity.

Cyanide and lactate levels in patients during chronic oral amygdalin intake followed by intravenous amygdalin administration.

The natural compound amygdalin has gained high popularity among tumor patients as a complementary or alternative treatment option. However, due to metabolization of amygdalin to cyanide (HCN) following oral consumption, there could be a high risk of lactic acidosis caused by cyanide intoxication. The present retrospective study was undertaken to evaluate cyanide blood and lactate plasma levels of tumor patients (n = 55) before and after intravenous (i.v.) amygdalin infusion. All patients had also continuously ingested amygdalin tablets (3 x 500 mg/day), excepting on the days of i.v. administration. Each patient received one to five intravenous amygdalin treatments. The time period between each i.v. application ranged between 4-6 days. The initial i.v. dose was 6 mg (n = 28), 9 mg (n = 1), 15 mg (n = 1) or 18 mg (n = 25). The mean cyanide blood level before i.v. amygdalin administration was 34.74 µg/L, which increased significantly to a mean value of 66.20 µg/L after i. v. amygdalin application. In contrast, lactate decreased significantly from 1266 µmol/L pre-infusion to 868 µmol/L post-infusion. Increasing i.v. amygdalin by 1 mg was also associated with a significant increase in the cyanide level, while the lactate blood level significantly decreased. This is the first study evaluating cyanide levels under conditions employed by amygdalin administrators, i.e. after chronic oral amygdalin intake and then again after a closely subsequent intravenous amygdalin administration. Since lactate decreased, whilst cyanide increased, it is concluded that elevation of cyanide does not induce metabolic acidosis in terms of an increased lactate level.

Subacute exposure to amygdalin influences compact bone remodeling of rabbits.

Amygdalin is most commonly occurring cyanogenic glycoside. It is found in seeds of many plant species. Our study was aimed to reveal whether pure intramuscularly injected amygdalin or apricot seeds peroral exposure cause changes in bone microstructure of rabbits. Twenty clinically healthy 5 months-old male rabbits were segregated into five groups. Animals from groups A1 and A2 were intramuscularly injected with amygdalin at doses of 0.6 and 3 mg/kg b.w. daily for 28 days. The groups S1 and S2 received commercial feed for rabbits mixed with crushed bitter apricot seeds at doses of 60 and 300 mg/kg b.w. during 28 days. The control (C) group did not receive any amygdalin. Intramuscular and peroral amygdalin administration did not affect total body weight, femoral length and femoral weight of rabbits. Similarly, microcomputed tomography (3D analysis) has shown that amygdalin had insignificant effect on relative bone volume, bone mineral density, cortical bone thickness, bone surface, trabecular thickness, trabecular number, trabecular separation. However, histological (2D analysis) revealed evident changes in compact bone microstructure of amygdalin-exposed rabbits consistent with a different vascularization and changed biomechanical properties. We can conclude that subacute exposure to amygdalin (both intramuscular and peroral) at the doses used in our study influenced compact bone remodeling.

Amygdalin (Vitamin B17) pretreatment attenuates experimentally induced acute autoimmune hepatitis through reduction of CD4+ cell infiltration.

BACKGROUND: Autoimmune hepatitis (AIH) is an immune-mediated inflammation of the liver characterized by disorganized hepatic parenchyma and inflammatory cell infiltration. Although the increased incidence of AIH, the development of novel therapeutic strategies are impeded by the poor understanding of the accompanied detailed immunopathogenic changes. CD4+ T cells are key mediators of inflammatory cell infiltration in initial phases of liver injuries like AIH. The distribution of CD4+ cells and the histopathological changes accompanying Con A-induced AIH were investigated together with the postulated protective effect of Amygdalin (Amg.). MATERIALS AND METHODS: 30 adult male mice were divided into three groups; control, AIH and AIH-Amg. groups. AIH was induced by a single intravenous injection of Concanavalin A (Con A) (15 mg/kg). The AIH-Amg. group received Amg. 5 mg/kg intraperitoneally once a week for three weeks. Blood samples were examined for ALT and AST. MDA, SOD, and GSH were determined in hepatic homogenates. Liver section stained with hematoxylin and eosin, Masson trichrome and CD4+ immune stain were examined by light and electron microscopy. RESULTS: AIH group showed a significant increase in levels of ALT, AST and MDA and a significant decline in SOD and GSH compared to the controls. The liver tissue showed distorted hepatic architecture with intercellular hemorrhage, necrosis, and inflammatory cell infiltration. The area percent of CD4+ immune staining was significantly increased. Electron microscopic examination showed massive cellular degenerative changes. Amg. pretreatment in AIH-Amg. group significantly reversed these changes. CONCLUSION: AIH induced CD4+ cells infiltration in the liver with subsequent liver tissue damage. Amg. pretreatment inhibited CD4+ cell infiltration and protected the liver tissue. This finding suggests that Amg. could be a therapeutic agent in the management of AIH.

The use of polysulfated polysaccharides heparin like compounds, glycosaminoglycans and Vitamin B17 as a possible treatment for prostate cancer.

Prostate cancer is impacting many men globally. It is a disease that has no effective treatment is available in the market. The understanding of the biophysical and biochemical aspects of the disease and the mechanism that allow it to metastasize is key to finding an effect treatment. Maintenance or pretreatment drug as well as a post treatment drug can be effective to avoid or delay the disease from appearing. The polysaccharides and monosaccharides polymers combined with vitamins can be the ingredient to developing the treatment. There are many evidences that investigators examined the individual components of the therapy proposed but never a combination of all these therapies. The one item that is not discussed is how to formulate the ingredient into an effective form which is a proprietary work being conducted currently. Nevertheless, the hypothesis seems reasonable to us and worth sharing with the scientific community.

Pharmacokinetics, Safety, and Tolerability of Amygdalin and Paeoniflorin After Single and Multiple Intravenous Infusions of Huoxue-Tongluo Lyophilized Powder for Injection in Healthy Chinese Volunteers.

PURPOSE: Huoxue-Tongluo lyophilized powder for injection (HTLPI), a traditional Chinese medicine preparation, is a compound of Persicae semen and Paeoniae Radix Rubra that is used mainly for treating blood-stasis obstruction syndrome in the acute stage of cerebral ischemic stroke. Amygdalin (AD) and paeoniflorin (PF) are 2 typical bioactive components in HTLPI and were selected as indicators for this pharmacokinetic study of HTLPI. The objective of this study was to investigate the safety profile, tolerability, and pharmacokinetic properties of AD and PF after single and multiple intravenous infusions of HTLPI in healthy Chinese volunteers. METHODS: Twenty-one healthy Chinese subjects were recruited for this open-label, single ascending-dose (3, 6, and 9 g) and multiple-dose (6 g, once daily) study. Safety profile was assessed by adverse events and physical examination throughout the study. Serial plasma and urine samples were analyzed by HPLC-MS/MS. Pharmacokinetic parameters of AD and PF were calculated using noncompartmental analysis. FINDINGS: In the single-dose phase of the study, the mean maximum plasma concentration and the mean area under the plasma concentration-time curve of AD and PF increased proportionally with each dose escalation. In the multiple-dose phase, the steady state was achieved by day 4 after multiple-dose administration of 6 g HTLPI. Mean pharmacokinetic parameters achieved on day 1 were similar to those on day 7. No significant accumulation was observed after repeat doses of 6 g HTLPI. Approximately 79.6% of the administered AD and 48.4% of the administered PF were excreted unchanged in urine within 24 hours. No serious adverse events were observed during the entire study. IMPLICATIONS: The pharmacokinetic properties of AD and PF were linear after a single intravenous infusion of HTLPI in the dose range of 3-9 g. No systemic accumulation was observed with repeat doses of HTLPI. Sex had no significant effect on the pharmacokinetic properties of AD and PF. Intravenous infusion of HTLPI was well tolerated in healthy Chinese subjects.

Integrated identification, qualification and quantification strategy for pharmacokinetic profile study of Guizhi Fuling capsule in healthy volunteers.

Guizhi Fuling capsule (GZFL), a traditional Chinese medicine formulation, is widely used in China to relieve pain from dysmenorrhea and is now in a Phase II clinical trial in the USA. Due to the low exposure of the five main medicative ingredients (amygdalin, cinnamic acid, gallic acid, paeoniflorin and paeonol) of GZFL in human, a strategy was built to qualitatively and quantitatively identify the possible metabolites of GZFL and to describe the pharmacokinetic profiles of GZFL in human. In this strategy, LC-Q-TOF/MS was used to identify and structurally elucidate the possible metabolites of GZFL in vivo; and a time-based metabolite-confirming step (TBMCs) was used to confirm uncertain metabolites. The simultaneously quantitation results by LC-MS/MS showed low exposure of the five medicative ingredients. According to the strategy we built, a total of 36 metabolites were found and structurally elucidated. The simultaneously semi-quantitative analysis by LC-MS/MS showed that obvious time-concentration curves could be established for 12 of the metabolites, and most of them showed a relatively higher exposure. This study provides a better understanding of the metabolic processes of GZFL in human.

Amygdalin inhibits the growth of renal cell carcinoma cells in vitro.

Although amygdalin is used by many cancer patients as an antitumor agent, there is a lack of information on the efficacy and toxicity of this natural compound. In the present study, the inhibitory effect of amygdalin on the growth of renal cell carcinoma (RCC) cells was examined. Amygdalin (10 mg/ml) was applied to the RCC cell lines, Caki-1, KTC-26 and A498, for 24 h or 2 weeks. Untreated cells served as controls. Tumor cell growth and proliferation were determined using MTT and BrdU tests, and cell cycle phases were evaluated. Expression of the cell cycle activating proteins cdk1, cdk2, cdk4, cyclin A, cyclin B, cyclin D1 and D3 as well as of the cell cycle inhibiting proteins p19 and p27 was examined by western blot analysis. Surface expression of the differentiation markers E- and N-cadherin was also investigated. Functional blockade by siRNA was used to determine the impact of several proteins on tumor cell growth. Amygdalin treatment caused a significant reduction in RCC cell growth and proliferation. This effect was correlated with a reduced percentage of G2/M-phase RCC cells and an increased percentage of cells in the G0/1-phase (Caki-1 and A498) or cell cycle arrest in the S-phase (KTC-26). Furthermore, amygdalin induced a marked decrease in cell cycle activating proteins, in particular cdk1 and cyclin B. Functional blocking of cdk1 and cyclin B resulted in significantly diminished tumor cell growth in all three RCC cell lines. Aside from its inhibitory effects on growth, amygdalin also modulated the differentiation markers, E- and N-cadherin. Hence, exposing RCC cells to amygdalin inhibited cell cycle progression and tumor cell growth by impairing cdk1 and cyclin B expression. Moreover, we noted that amygdalin affected differentiation markers. Thus, we suggest that amygdalin exerted RCC antitumor effects in vitro.

Amygdalin delays cell cycle progression and blocks growth of prostate cancer cells in vitro.

AIMS: Despite impressive survival benefits from new agents to treat metastasized prostate cancer (PCa), progressive drug resistance hinders long-term response and restricts the efficacy of subsequent therapy. Due to reported antitumor activity of amygdalin and growing popularity for complementary and alternative medicine the potential of this natural, widely used substance to exert antineoplastic effects on prostate cancer cells has been assessed. MAIN METHODS: LNCaP (castration-sensitive), DU-145 and PC3 cells (castration-resistant) were exposed to different concentrations of amygdalin for 24h or 2weeks. Cell growth was measured by the MTT test, clonal formation by the clonogenic assay. Flow cytometry served to investigate apoptosis and cell cycle phases. Cell cycle regulating proteins and the mTOR-akt signaling axis were analyzed by western blotting. KEY FINDINGS: Amygdalin dose-dependently diminished tumor cell growth with maximum effects at 10mg/ml. Apoptosis of PC3 and LNCaP but not of DU-145 cells was reduced, whereas colony formation was suppressed in all cell lines. A decrease in the number of G2/M- and S-phase cells along with an elevated number of G0/G1-phase cells was recorded. The cell cycle proteins cdk 1, cdk 2 and cdk 4 as well as cyclin A, cyclin B and cyclin D3 were modulated by amygdalin after both 24h and 2weeks. Distinct effects on p19 and p27 expression and on Akt, Rictor and Raptor activation became evident only after 2weeks. SIGNIFICANCE: Amygdalin exhibits significant antitumor activity in both castration-sensitive and castration-resistant PCa cell lines and merits further evaluation for therapeutic purposes.

Studies on high-dose chemotherapy of amygdalin in murine P388 lymphocytic leukaemia and P815 mast cell leukaemia.

The anti-tumor activity of amygdalin (NSC 251222), commercially known as Laetrile, was investigated using P388 lymphocytic leukaemia and P815 mast-cell leukaemia in BDF1 mice. Doses varying from 200 mg/kg to 2,000 mg/kg were used following the days 1 and 5 and days 1, 5 and 9 schedules. Despite treatment with high doses of amygdalin there was no prolongation in the life-span of mice bearing either P388 or P815 tumor.

Pharmacology of amygdalin (laetrile) in cancer patients.

Plasma and urine concentrations of amygdalin, whole-blood concentrations of cyanide, and thiocyanate concentrations in serum and urine were determined in cancer patients following intravenous (4.5 g/m2) and oral (500-mg tablet) administration of amygdalin. To measure low plasma concentrations of amygdalin following oral administration a GC/MS assay was developed. Following intravenous administration, concentrations of parent drug as high as 1,401 microgram/ml were observed, with no increase in plasma concentrations of cyanide or serum concentrations of thiocyanate. Plasma elimination of amygdalin was best described by a two-compartment open model with a mean distributive phase half-life of 6.2 min, mean elimination phase half-life of 120.3 min, and mean clearance of 99.3 ml/min. Following oral administration of amygdalin, plasma concentrations were much lower, with peak values of less than 525 ng/ml. Cyanide concentrations increased to values as high as 2.1 microgram/ml whole blood. Thiocyanate concentrations did not increase for several days, plateauing at values as high as 38 microgram/ml serum. Ingestion of almonds by two patients taking oral amygdalin increased cyanide concentrations compared with values obtained after oral amygdalin alone.

Advanced research on anti-tumor effects of amygdalin.

Malignant tumors are the major disease that cause serious damage to human health, and have been listed as the premier diseases which seriously threatened human health by World Health Organization (WHO). In recent years the development of antitumor drugs has been gradually transformed from cytotoxic drugs to improving the selectivity of drugs, overcoming multidrug resistance, development of new targeted drugs and low toxicity with high specificity drugs. Amygdalin is a natural product that owns antitumor activity, less side effects, widely sourced and relatively low priced. All these features make the amygdalin a promising antitumor drugs, if combined with conditional chemotherapy drugs, which can produce synergistic effect. In this paper, we summarized the pharmacological activity, toxicity and antitumor activity of amygdalin, mainly focused on the advanced research of amygdalin on its antitumor effects in recent years, providing new insights for the development of new anticancer drugs, new targets searching and natural antitumor mechanism investigations.

Amygdalin inhibits angiogenesis in the cultured endothelial cells of diabetic rats.

BACKGROUND: Angiogenesis contributes to different physiological and pathological conditions. The aim of this study was to investigate for the first time the antiangiogenic effects of amygdalin on the cultured endothelial cells of diabetic rats. MATERIALS AND METHODS: A total of 20 streptozotocin-induced diabetic rats were divided into two equal groups of control and amygdalin-treated animals. Eight weeks after the induction of diabetes, amygdalin was injected intraperitoneally (3 mg/kg) to the rats of the treatment group. One day later, rats were sacrificed; the aortic arteries were excised and cut as 2 mm rings. Each aortic ring was incubated in a cell-culture well for 7 days. The process of angiogenesis was monitored by counting the number of microvessels and primary microtubules in each well. RESULTS: Optic microscopy showed proliferation and migration of new endothelial cells to the fibrin gels. The endothelial cells produced primary microtubules which gradually made several branches and finally made a vascular matrix. The number of the primary microtubules and microvessels were significantly lower in the amygdalin-treated vs. control group (P < 0.01). CONCLUSION: Therefore, amygdalin exerts inhibitory effects on angiogenesis in aortic rings of diabetic rats and may pave a new way for treatment of unfavorable angiogenic conditions.

Parallel reinforcement pathways for conditioned food aversions in the honeybee.

Avoiding toxins in food is as important as obtaining nutrition. Conditioned food aversions have been studied in animals as diverse as nematodes and humans [1, 2], but the neural signaling mechanisms underlying this form of learning have been difficult to pinpoint. Honeybees quickly learn to associate floral cues with food [3], a trait that makes them an excellent model organism for studying the neural mechanisms of learning and memory. Here we show that honeybees not only detect toxins but can also learn to associate odors with both the taste of toxins and the postingestive consequences of consuming them. We found that two distinct monoaminergic pathways mediate learned food aversions in the honeybee. As for other insect species conditioned with salt or electric shock reinforcers [4-7], learned avoidances of odors paired with bad-tasting toxins are mediated by dopamine. Our experiments are the first to identify a second, postingestive pathway for learned olfactory aversions that involves serotonin. This second pathway may represent an ancient mechanism for food aversion learning conserved across animal lineages.

Blood cyanide levels in mice after administration of amygdalin.

Oral doses of amygdalin and intraperitoneal (i.p.) doses of potassium cyanide (KCN) in the near-lethal range were administered to CD2F1 female mice. Blood cyanide levels were then measured as a function of time. The maximum cyanide level after amygdalin administration was reached at about 11/2 to 2 h and was within the range of values seen after KCN administration. Behaviour of mice correlated with the time of maximum blood cyanide level. Acute distress was observed at times when the cyanide level was highest. There was great variability in the nature and magnitude of the response in individual mice. The ability of the contents of various regions of the gastrointestinal tract and of tumour tissue to release cyanide from amygdalin was assessed. Stomach and upper intestine had little activity while the lower end and the faeces released large amounts. Again, there was a large variation between mice. These results are interpreted to mean that enteric contents are primarily responsible for the release of cyanide from ingested amygdalin. Freshly minced tumour tissue released negligible amounts of cyanide. Ten-fold higher doses of amygdalin administered i.p. produced very small increases in blood cyanide levels and no toxic behaviour. The doses used are comparable to doses which might be ingested by patients receiving oral amygdalin or Laetrile and indicate that oral amygdalin is potentially extremely dangerous.