Rebound effect of modern drugs: serious adverse event unknown by health professionals

Control of Orthodontic Tooth Movement by Nitric Oxide Releasing Nanoparticles in Sprague-Dawley Rats

Orthodontic treatment commonly requires the need to prevent movement of some teeth while maximizing movement of other teeth. This study aimed to investigate the influence of locally injected nitric oxide (NO) releasing nanoparticles on orthodontic tooth movement in rats.

MATERIALS AND METHODS

Experimental tooth movement was achieved with nickel-titanium alloy springs ligated between the maxillary first molar and ipsilateral incisor. 2.2 mg/kg of silica nanoparticles containing S-nitrosothiol groups were injected into the mucosa just mesial to 1^st molar teeth immediately prior to orthodontic appliance activation. NO release from nanoparticles was measured in vitro by chemiluminescence. Tooth movement was measured using polyvinyl siloxane impressions. Bones were analyzed by microcomputed tomography. Local tissue was assessed by histomorphometry.

RESULTS

Nanoparticles released a burst of NO within the first hours at approximately 10 ppb/mg particles that diminished by 10 × to approximately 1 ppb/mg particles over the next 1-4 days, and then diminished again by tenfold from day 4 to day 7, at which point it was no longer measurable. Molar but not incisor tooth movement was inhibited over 50% by injection of the NO releasing nanoparticles. Inhibition of molar tooth movement occurred only during active NO release from nanoparticles, which lasted for approximately 1 week. Molar tooth movement returned to control levels of tooth movement after end of NO release. Alveolar and long bones were not impacted by injection of the NO releasing nanoparticles, and serum cyclic guanosine monophosphate (cGMP) levels were not increased in animals that received the NO releasing nanoparticles. Root resorption was decreased and periodontal blood vessel numbers were increased in animals with appliances that were injected with the NO releasing nanoparticles as compared to animals with appliances that did not receive injections with the nanoparticles.

CONCLUSION

Nitric oxide (NO) release from S-nitrosothiol containing nanoparticles inhibits movement of teeth adjacent to the site of nanoparticle injection for 1 week. Additional studies are needed to establish biologic mechanisms, optimize efficacy and increase longevity of this orthodontic anchorage effect.

Chronic angiotensin receptor activation promotes hepatic triacylglycerol accumulation during an acute glucose challenge in obese-insulin-resistant OLETF rats

PURPOSE

Angiotensin receptor blockers (ARBs) can ameliorate metabolic syndrome (MetS)-associated dyslipidemia, hepatic steatosis, and glucose intolerance, suggesting that angiotensin receptor (AT1) over-activation contributes to impaired lipid and glucose metabolism, which is characteristic of MetS. The aim of this study was to evaluate changes in the lipid profile and proteins of fatty acid uptake, triacylglycerol (TAG) synthesis, and β-oxidation to better understand the links between AT1 overactivation and non-alcoholic fatty liver disease (NAFLD) during MetS.

METHODS

Four groups of 25-week-old-rats were used: (1) untreated LETO, (2) untreated OLETF, (3) OLETF + angiotensin receptor blocker (ARB; 10 mg olmesartan/kg/d × 8 weeks) and (4) OLETF ± ARB (MINUS; 10 mg olmesartan/kg/d × 4 weeks, then removed until dissection). To investigate the dynamic shifts in metabolism, animals were dissected after an oral glucose challenge (fasting, 3 and 6 h post-glucose).

RESULTS

Compared to OLETF, plasma total cholesterol and TAG remained unchanged in ARB. However, liver TAG was 55% lesser in ARB than OLETF, and remained lower throughout the challenge. Basal CD36 and ApoB were 28% and 29% lesser, respectively, in ARB than OLETF. PRDX6 abundance in ARB was 45% lesser than OLETF, and it negatively correlated with liver TAG in ARB.

CONCLUSIONS

Chronic blockade of AT1 protects the liver from TAG accumulation during glucose overload. This may be achieved by modulating NEFA uptake and increasing TAG export via ApoB. Our study highlights the contributions of AT1 signaling to impaired hepatic substrate metabolism and the detriments of a high-glucose load and its potential contribution to steatosis during MetS.

"Similia Similibus Curentur": The scientific grounding of the homeopathic therapeutic principle through the systematic study of the rebound effect of modern drugs

• Homeopathy employs the principle of therapeutic similitude as a method of treatment. • Primary action of drugs is followed by secondary and opposite reaction of the organism. • This secondary and opposite reaction of the organism is namely the rebound effect of drugs. • Homeopathy employs the rebound effect of drugs in a therapeutic way.

Neurotoxic effects of pregabalin dependence on the brain frontal cortex in adult male albino rats

Pregabalin (PGB) is an analog of the inhibitory neurotransmitter gamma-aminobutyric acid. The currently available evidence favors the misuse and abuse potential of PGB. However, its neurotoxicity remains unclear. Therefore, this study assessed the toxic effects of chronic pregabalin dependence as well as withdrawal on the cortical neurons of the frontal lobe. This study included eighty adult male albino rats which were divided into three groups. Group I (Control) included 40 rats and was further subdivided into two equal subgroups (IA and IB) as negative and positive controls. Group II (PGB-dependent) included 20 rats which received PGB starting with the therapeutic dose (300 mg/day), then the doses were gradually increased until they reached the dependent dose (3400 mg/day) by the end of the first month. Further, the dependent dose was given daily for another 2 months. Group III (PGB withdrawal) included 20 rats which received PGB as described in group II. After that, administration of PGB was stopped and the rats were kept for another one month. By the end of the experiment, all animals were sacrificed by cervical decapitation. The specimens were taken from the frontal cortex for histologic and immunohistochemical staining as well as morphometric analysis. Sections of the frontal cortex of group II showed changes in the form of disturbed architectural pattern of cortical layers, apoptotic cells, weak immunoexpression of Bcl-2 and VEGF as well as moderate-strong immunoexpression of iNOS and nestin. These expressions were significantly different from the control groups, but they were non-significant in comparison with group III. These findings indicate that chronic PGB dependence induces neurotoxic effects mainly in the form of neuronal apoptosis, gliosis, and oxidative stress injury of the frontal cortex. The PGB- induced neurotoxic effects persisted after withdrawal. The influence of these neurotoxic effects and their relevance to the cognitive or neurologic disorders in PGB-dependent individuals warrants further research. Furthermore, it is recommended to quantify the behavioral changes related to PGB dependence as well as withdrawal in future studies.

Pregabalin administration and withdrawal affect testicular structure and functions in rats

The aim of this prospective experimental study was to investigate the effects of pregabalin (PG) administration and withdrawal on testicular structures and functions in rats. A total of 24 male Wistar rats were divided into two groups (n = 12 each): a control group received normal saline, and PG-treated group received 62 mg kg^-1  day^-1 PG for 2 months. Half the animals of each group were sacrificed for the collection of blood and testicular samples. The remaining animals were bred for another 2 months without treatment before collection of blood and testicular samples. PG administration decreased testosterone and increased luteinising hormone (LH) and follicle-stimulating hormone (FSH) levels versus controls. PG withdrawal led to a decrease in both FSH and LH and an increase in testosterone levels versus saline withdrawal. Compared to controls, PG administration caused degeneration of seminiferous tubules and decreased the number of spermatogenic but increased the number of Leydig cells. After PG withdrawal, these cells showed a rebound reverse. Reduced glutathione levels increased with PG administration while PG withdrawal increased malondialdehyde levels. Conclusion: PG administration affected testicular morphometry, gonadotrophic and sex hormones; however, there was a rebound reversal in all these parameters and a significant oxidative stress in PG withdrawal.

Vagotomy influences the lung response to adrenergic agonists and muscarinic antagonists

Mammals airways are extensively innervated by the vagus nerve, which controls the airway diameter and bronchial tone. However, very few studies described the respiratory function and lung morphology after vagal section. In the present study, we evaluated the respiratory mechanics after aerosolization of vehicle (to obtain control values), a muscarinic agonist (methacholine), a β₂-adrenergic agonist (salbutamol) or a muscarinic antagonist (ipratropium bromide) in intact (Vi) and bilaterally vagotomized (Vx) Swiss male mice. Different group was established for morphometric analyze. The total lung resistance, airway resistance, elastance, compliance, lung tissue damping, lung tissue elastance, and morphological parameters (collagen and elastic fibers) were significantly different in the Vx group compared to the Vi group. Bronchoconstrictor and bronchodilators change the respiratory function of the Vx group. In conclusion, the vagus nerve modulates the lung function in response to bronchoconstriction and bronchodilation, as well as lung architecture of mice.

Biological therapies (immunomodulatory drugs), worsening of psoriasis and rebound effect: new evidence of similitude

BACKGROUND

Employing the secondary action or adaptative reaction of the organism as therapeutic response, homeopathy uses the treatment by similitude (similia similibus curentur) administering to sick individuals the medicines that caused similar symptoms in healthy individuals. Such homeostatic or paradoxical reaction of the organism is scientifically explained through the rebound effect of drugs, which cause worsening of symptoms after withdrawal of several palliative treatments. Despite promoting an improvement in psoriasis at the beginning of the treatment, modern biological therapies provoke worsening of the psoriasis (rebound psoriasis) after discontinuation of drugs.

METHOD

Exploratory qualitative review of the literature on the occurrence of the rebound effect with the use of immunomodulatory drugs [T-cell modulating agents and tumor necrosis factor (TNF) inhibitors drugs] in the treatment of psoriasis.

RESULTS

Several researches indicate the rebound effect as the mechanism of worsening of psoriasis with the use of efalizumab causing the suspension of its marketing authorization in 2009, in view of some severe cases. Other studies also have demonstrated the occurrence of rebound psoriasis with the use of alefacept, etanercept and infliximab.

CONCLUSION

As well as studied in other classes of drugs, the rebound effect of biologic agents supports the principle of similitude (primary action of the drugs followed by secondary action and opposite of the organism).

Protocol of randomized controlled trial of potentized estrogen in homeopathic treatment of chronic pelvic pain associated with endometriosis

BACKGROUND

Endometriosis is a chronic inflammatory disease that causes difficult-to-treat pelvic pain. Thus being, many patients seek help in complementary and alternative medicine, including homeopathy. The effectiveness of homeopathic treatment for endometriosis is controversial due to the lack of evidences in the literature. The aim of the present randomized controlled trial is to assess the efficacy of potentized estrogen compared to placebo in the treatment of chronic pelvic pain associated with endometriosis.

METHODS/DESIGN

The present is a randomized, double-blind, placebo-controlled trial of a homeopathic medicine individualized according to program 'New Homeopathic Medicines: use of modern drugs according to the principle of similitude' (http://newhomeopathicmedicines.com). Women with endometriosis, chronic pelvic pain and a set of signs and symptoms similar to the adverse events caused by estrogen were recruited at the Endometriosis Unit of Division of Clinical Gynecology, Clinical Hospital, School of Medicine, University of São Paulo (Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo - HCFMUSP). The participants were selected based on the analysis of their medical records and the application of self-report structured questionnaires. A total of 50 women meeting the eligibility criteria will be randomly allocated to receive potentized estrogen or placebo. The primary clinical outcome measure will be severity of chronic pelvic pain. Statistical analysis will be performed on the intention-to-treat and per-protocol approaches comparing the effect of the homeopathic medicine versus placebo after 24 weeks of intervention.

DISCUSSION

The present study was approved by the research ethics committee of HCFMUSP and the results are expected in 2016.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: https://clinicaltrials.gov/ct2/show/NCT02427386.