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There’s more Thiotepa is used for the treatment of intracavitary effusions (accu- mulation of fluid in a body cavity) purchase slimex 10 mg overnight delivery. It’ll take your breath away Adverse When used with succinylcholine buy generic slimex 15 mg, thiotepa may cause prolonged respirations and apnea (periods of not breathing) order 15mg slimex with amex. Thiotepa ap- reactions pears to inhibit the activity of cholinesterase buy 10 mg slimex amex, the enzyme that de- to thiotepa activates succinylcholine. Because their action resembles that of a and pancytopenia (defi- bifunctional alkylating drug, they are referred to as alkylating-like ciency of all cellular ele- drugs. Pharmacokinetics Other adverse reac- The distribution and metabolism of carboplatin aren’t defined tions include: clearly. It (commonly) has an initial half-life of 1 to 2 hours and a terminal half-life of • stomatitis and ulcera- 21⁄2to 6 hours. In patients with decreased renal function, the ter- tion of the intestinal mu- minal half-life of carboplatin may last from 30 to 300 hours. Oxali- cosa (especially at bone platin is 70% to 90% bound to plasma proteins, and the protein- marrow transplantation binding increases over time. It’s widely distributed into most body doses) tissues and is eliminated in phases. Into the lungs and peritoneum When administered intrapleurally (into the pleural space around the lung) or intraperitoneally (into the peritoneum), cisplatin may exhibit significant systemic absorption. The drug undergoes some liver metabolism, followed by ex- cretion through the kidney. Going platinum Platinum is detectable in tissue for at least 4 months after admin- istration. Pharmacotherapeutics These alkylating-like drugs are used in the treatment of several Adverse cancers. Normal cells that are reproducing actively, as well as the cancer cells, are af- fected by the antimetabolites. Folic acid analogues Although researchers have developed many folic acid analogues, the early compound methotrexate remains the most commonly used. Pharmacokinetics Methotrexate is well absorbed and distributed throughout the body. It can accumulate in any fluid collection, such as ascites or pleural or pericardial effusion, possibly resulting in prolonged elimination and higher than expected toxicity, especially myelo- suppression. Metabolism and excretion Although methotrexate is metabolized partially, it’s excreted pri- marily unchanged in urine. A disappearing act Methotrexate exhibits a three-part disappearance from plasma; the rapid distributive phase is followed by a second phase, which reflects kidney clearance. The last phase, the terminal half-life, is 3 to 10 hours for a low dose and 8 to 15 hours for a high dose. Methotrexate is especially useful in treating the most Pharmacodynamics common childhood Methotrexate reversibly inhibits the action of the enzyme dihydro- leukemia. Folinic acid is used in high-dose methotrexate therapy to help prevent cell death. Kidney concerns • Salicylates and nonsteroidal anti-inflammatory drugs, especially With high doses, kidney diclofenac, ketoprofen, indomethacin, and naproxen, also in- toxicity can also occur crease methotrexate toxicity. It consists of a sugar, a nitrogen-containing Climbing the ladder to understanding base, and a phosphate group. Cytosine and thymine are pyrimidines; After pyrimidine analogues are converted into adenine and guanine are purines. Pharmacokinetics Because pyrimidine analogues are poorly absorbed when they’re given orally, they’re usually administered by other routes. Pharmacodynamics Pyrimidine analogues kill cancer cells by interfering with the nat- ural function of pyrimidine nucleotides. Adverse reactions to pyrimidine analogues Like most antineoplastic drugs, pyrimidine ana- • Diarrhea logues can cause: • Fever • fatigue and lack of energy • Hand-foot syndrome • inflammation of the mouth, esophagus, and • Crab erythema (when high-dose cytarabine throat is combined with continuous infusions of fluo- • bone marrow suppression rouracil) • nausea and anorexia. Fluorouracil With Cytarabine • Diarrhea pyrimidine • Severe cerebellar neurotoxicity • Hair loss analogues, we • Chemical conjunctivitis • Mucositis (when combined with folinic acid) may all win! Drug interactions No significant drug interactions occur with most of the pyrimidine analogues; however, several drug interactions are possible with capecitabine. They include: • fludarabine phosphate • cladribine • mercaptopurine • pentostatin • thioguanine. Pharmacodynamics As with the other antimetabolites, fludarabine, mercaptopurine, and thioguanine first must be converted via phosphorylation (in- troduction to a phosphate) to the nucleotide level to be active. Analogous to pyrimide analogues This conversion to nucleotides is the same process that pyrimi- dine analogues go through but, in this case, it’s purine nucleotides that are affected. Purine analogues are cell cycle–specific as well, exerting their effect during that same S phase. Fludarabine, when used at high doses, may Down to the bone cause severe neurologic • Concomitant administration of mercaptopurine and allopurinol effects, including blind- may increase bone marrow suppression by decreasing mercapto- ness, coma, and death. They include: • anthracyclines (daunorubicin, doxorubicin, idarubicin) • bleomycin • dactinomycin • mitomycin • mitoxantrone. Direct deliveries Some drugs are also administered directly into the body cavity be- ing treated. Bleomycin, doxorubicin, and mitomycin are some- times given as topical bladder instillations, resulting in minimal systemic absorption. When bleomycin is injected into the pleural space for malignant effusions, up to one-half of the dose is ab- sorbed systemically. Distribution, metabolism, and excretion Distribution of antibiotic antineoplastic drugs throughout the body varies; their metabolism and elimination also vary. Clean break Mitomycin is activated inside the cell to a bifunctional or even tri- functional alkylating drug. Ir- • melanoma • osteogenic sarcoma and rhabdomyosarcoma (malignant neo- reversible cardiomyopa- plasm composed of striated muscle cells) thy and acute electro- • squamous cell carcinoma of the head, neck, and cervix cardiogram changes • testicular cancer can also occur as well • Wilms’ tumor (a malignant neoplasm of the kidney, occurring in as nausea and vomiting. Extra steps An antihistamine and an Drug interactions antipyretic should be Antibiotic antineoplastic drugs interact with many other drugs. Hormonal antineoplastic drugs and hormone modulators Hormonal antineoplastic drugs and hormone modulators are prescribed to alter the growth of malignant neoplasms or to man- age and treat their physiologic effects. Aromatase inhibitors In postmenopausal women, estrogen is produced through aromatase, an enzyme that converts hormone precursors into estrogen. Aromatase inhibitors prevent androgen from being converted into estrogen in postmenopausal women, thereby blocking estrogen’s ability to activate can- cer cells; limiting the amount of estrogen means that less estrogen is available to reach cancer cells and make them grow. Type 1, or steroidal, inhibitors include exemestane; type 2, or nonsteroidal, inhibitors include anastrozole and letrozole. Pharmacokinetics Aromatase inhibitors are taken orally (in pill form) and are usually well tolerated. Pharmacodynamics Aromatase inhibitors work by lowering the body’s production of estrogen. In about one-half of all patients with breast cancer, the tumors depend on estrogen to grow. Aromatase inhibitors are used only in postmenopausal women because they lower the Memory amount of estrogen that’s produced outside the ovaries, such as in jogger muscle and fat tissue.
Antihypertensive effcacy of α-methyldopa purchase 15mg slimex, chlorothiazide and Supres-150 (α-methyldopa-chlorothiazide) order 10 mg slimex free shipping. The inhibition of trasylol of fb- rinolytic activity associated with cardiovascular operations discount 10 mg slimex amex. Solu- tion structure of recombinant hirudin and the Lys-47-Glu mutant: a nuclear magnetic resonance and hybrid distance geometry-dynamical simulated annealing study purchase 15 mg slimex visa. Conformation of recombinant desulfatohirudin in aqueous solution determined by nuclear magnetic resonance. Cyclic amides of N-α-arylsulfonylaminoacylated 4-amidinophenylalanine-tight binding inhibitors of thrombin. Potent nonco- valent thrombin inhibitors that utilize the unique amino acid D-dicyclohexylalanine in the P3 position. Glucagon-like peptide-1: The basis of a new class of treatment for type 2 diabetes. Crit Rev Biochem Mol Biol 1993;28:31–81; (c) Lu I-L, Tsai K-C, Chiang Y-K, Jiaang W-T, Wu S-H, Mahindroo N, Chien C-H, Lee S-J, Chen X, Chao Y-S, Wu S-Y. Inhibition of pressor effects of angiotensin I and augmentation of depressor effects of bradykinin by synthetic peptides. Design of specifc inhibitors of angiotensin-converting enzyme: new class of orally active antihypertensive agents. Orally potent human renin inhibitors derived from angiotensinogen transition state: design, synthesis, and mode of interaction. Synthesis and biological activity of some transition-state inhibitors of human renin. Structure-based drug design: the discovery of novel nonpeptide orally active inhibitors of human renin. Aliskiren, a novel orally effective renin inhibitor, provides dose-dependent antihypertensive effcacy and placebo-like tolerability in hypertensive patients. On the antibacterial action of cultures of a penicillium, with special ref- erence to their use in the isolation of B. Two sets of paralogous genes encode the enzymes involved in the early stages of clavulanic acid and clavam metabolite biosyn- thesis in Streptomyces clavuligerus. Biochemistry 2007;46:8980–8987; (b) The Piperacillin/Tazobactam Skin and Skin Structure Study Group. Treatment of hospitalized patients with compli- cated skin and skin structure infections: double-blind, randomized, multicenter study of piperacillin-tazobactam versus ticarcillin-clavulanate. The renal mem- brane dipeptidase (dehydropeptidase I) inhibitor, cilastatin, inhibits the bacte- rial metallo-beta-lactamase enzyme CphA. Mimoto T, Kato R, Takaku H, Nojima S, Terashima K, Misawa S, Fukazawa T, Ueno T, Sato H, Shintani M, Kiso Y, Hayashi H. Pharmacokinetic enhancement of inhibitors of the human immunodef- ciency virus protease by coadministration with ritonavir. Kiso Y, Yamaguchi S, Matsumoto H, Mimoto T, Kato R, Nojima S, Takaku H, Fukazawa T, Kimura T, Akaji K. Inhibition of bone resorption by selective inac- tivators of cysteine proteinases. Synthesis of peptide aldehyde derivatives as selective inhibitors of human cathep- sin L and their inhibitory effect on bone resorption. Inhibition of carcinoma cell invasion and liver metastases formation by the cysteine proteinase inhibitor E-64. Cytokine 1996;8:377–386; (b) Norman J, Yang J, Fink G, Carter G, Ku G, Denham W, Livingston D. Views on amyloid hypothesis and secretase inhibitors for treating Alzheimer’s disease: progress and problems. Hamada Y, Ohta H, Miyamoto N, Yamaguchi R, Yamani A, Hidaka K, Kimura T, Saito K, Hayashi Y, Ishiura S, Kiso Y. Effects of a gamma-secretase inhibitor in a randomized study of patients with Alzheimer disease. Design, syn- thesis, X-ray crystallographic analysis, and structure-activity relationships for aseriesofP2-modifed, orally active peptidyl pentafuoroethyl ketones. Syntheses of trans-5-oxo-hexahydro-pyrrolo[3,2-b]pyrroles and trans-5-oxo-hexahydrofuro[3,2-b]pyrroles (pyrrolidine trans-lactams and trans-lactones): New pharmacophores for elastase inhibition. Neutrophil elastase inhibitors as treatments for emphysema and chronic bronchitis. Candoxatril, an orally active neutral endopeptidase inhibitor, raises plasma atrial natriuretic factor and is natriuretic in essential hypertension. Effectiveness of endopeptidase inhibition (candoxatril) in congestive heart failure. Acute natriuretic effect of fasi- dotrilat, a mixed inhibitor of neutral endopeptidase and angiotensin I-converting enzyme, in rats with heart failure. Dual inhibition of angiotensin-converting enzyme and netural endopeptidase by the orally active inhibitor mixanpril: a potential therapeutic approach in hypertension. Combined inhibition of neutral endopeptidase and angiotensin-converting enzyme by sampatrilat in essential hypertension. Therapeutic potential and strategies for inhibiting tumor necro- sis factor-alpha. Human immunodefciency virus type 1 protease inhibitor attenuates Candida albicans virulence properties in vitro. High-affnity inhibition of a family of Plasmodium falciparum proteases by a designed adaptive inhibitor. Henriques Institute for Molecular Bioscience The University of Queensland, Brisbane, Queensland, Australia David J. Craik Institute for Molecular Bioscience The University of Queensland, Brisbane, Queensland, Australia 6. All organisms screen their environment and produce compounds that provide them with an evolutionary advan- tage [1, 2]. Thus, natural compounds are often the starting point for the design of drugs with high selectivity and potency [1–4]. Peptides are expressed in all living species and display a large diversity of structures and biological effects. Therefore it is not surprising that natural occurring peptides are attractive drug leads and are mak- ing their way into clinical applications [5–15]. A vast number of active peptides have been isolated and characterized from a broad variety of biological sources. Peptides involved in host defense and prey capture are among the best drug candidates, due to their fast-acting protection/capture mechanism. Organisms that produce host-defense peptides with potential applications in drug development include prokaryotes, plants, and animals, and we begin this article with brief descriptions of a few examples. Bacteria are a rich source of peptides with potential pharmaceutical appli- cations. Both Gram-negative and Gram-positive bacteria produce antimicrobial Peptide Chemistry and Drug Design, First Edition. Bacteriocins are attractive candidates both as antimicrobial agents for the treatment of human and animal infections, and as food preservatives [16–18].
This apparatus is easier to assem- (6) The mechanism to measure the ef- ble than the official apparatus and the back fectiveness of the experiment; pressure inside the apparatus is limited to (7) The method for conveying to con- the unavoidable pressure due to the height of the 3% H2O2 solution above the tip of the sumers the required nutrition and bubbler (F) cheap slimex 10 mg line. Keeping the backpressure as low other labeling information that is ex- as possible reduces the likelihood that sulfur empted from the label during the ex- dioxide will be lost through leaks purchase slimex 10 mg line. Each joint which a claim is made; and should be clamped together to ensure a com- (9) A statement of the sections of the plete seal throughout the analysis purchase slimex 10mg free shipping. The sepa- regulations for which an exemption is ratory funnel cheap 15mg slimex with mastercard, B, should have a capacity of sought. The proposal with sulfur dioxide, is deposited in the funnel should be clearly identified as a re- and the side arm. The gas inlet tube, D, (Kontes K– labeling experiments and submitted as 179000 or equivalent) should be of sufficient a citizen petition under §10. The bubbler, F, was fabricated from Foods labeled in violation of existing glass according to the dimensions given in regulations will be subject to regu- Fig. Just prior to use, small enough to pass through the 24/40 point add three drops of methyl red indicator and of flask C. Wipe the tapered (e) Nitrogen—A source of high purity nitro- joint clean with a laboratory tissue, apply gen is required with a flow regulator that stopcock grease to the outer joint of the will maintain a flow of 200 cc per minute. To separatory funnel, and return the separatory guard against the presence of oxygen in the funnel, B, to tapered joint flask C. The nitro- nitrogen, an oxygen scrubbing solution such gen flow through the 3% hydrogen peroxide as an alkaline pyrogallol trap may be used. Close Use a power setting which will cause 80 to 90 the stopcock of separatory funnel, B, and add drops per minute of condensate to return to 90 ml of 4N hydrochloric acid to the sepa- the flask from condenser, E. Begin the flow of nitrogen at of boiling the contents of the 1000 ml flask a rate of 200±10 cc/min. Compute the sulfite minutes the apparatus and the distilled content, expressed as micrograms sulfur di- water will be thoroughly de-oxygenated and oxide per gram of food (ppm) as follows: the apparatus is ready for sample introduc- tion. Add 100 ml of 5% endpoint; the factor, 1000, converts milli- ethanol in water and briefly grind the mix- equivalents to microequivalents and ture. Grinding or blending should be contin- Wt=weight (g) of food sample introduced into ued only until the food is chopped into pieces the 1000 ml flask. The following requirements shall Nonstandardized Foods apply unless modified by a specific reg- ulation in subpart B of this part. For each characterizing ingre- dient or component, the words "l per- Subpart A—General Provisions cent or %) lll" shall appear fol- lowing or directly below the word §102. The distinct contrast to other printed or name shall be uniform among all iden- graphic matter, and in a height not tical or similar products and may not less than the larger of the following al- be confusingly similar to the name of ternatives: any other food that is not reasonably (i) Not less than one-sixteenth inch encompassed within the same name. A neous impression that such ingre- petition requesting such a regulation, dient(s) or component(s) is present which would amend the applicable reg- when it is not, and consumers may oth- ulation, shall be submitted pursuant to erwise be misled about the presence or part 10 of this chapter. Specific Nonstandardized Foods (1) The presence or absence of a char- acterizing ingredient or component §102. The names "hydrolyzed vege- easily legible boldface print or type in table protein" and "hydrolyzed pro- distinct contrast to other printed or tein" are not acceptable because they graphic matter, and in a height not do not identify the food source of the less than the larger of the alternatives protein. The availability of this in- weight of the finished product, and the corporation by reference is given in overall biological quality of the pro- paragraph (c)(1) of this section. The availability of this in- the finished product, and the overall corporation by reference is given in biological quality of the protein con- paragraph (c)(1) of this section. This part of the corporation by reference is given in name shall be placed immediately fol- paragraph (c)(1) of this section. The word "frozen" pared by use of the package contents is also optional, provided that the (e. The 5-percent range, when used, shall be declared in the The common or usual name of a mix- manner set forth in §102. The term shall be in a a line(s) immediately below the words type size no less than one-half the "onion rings" in easily legible boldface height of the letters in the name of the print or type in distinct contrast to juice. However, if water is added to (2) Not less than one-half the height this 100 percent juice mixture to adjust of the largest type used in the words the Brix level, the product shall be la- "onion rings. I (4–1–10 Edition) the nutritional quality guideline estab- the guideline, shall be ineligible to lished for its class of food may state bear the guideline statement provided "This product provides nutrients in for in paragraph (b) of this section, and amounts appropriate for this class of such a product shall also be deemed to food as determined by the U. Govern- be misbranded under the act unless the ment," except that the words "this label and all labeling bear the fol- product" are optional. This statement, lowing prominent and conspicuous if used, shall be printed on the prin- statement: "The addition of lll to cipal display panel, and may also be (or "The addition of lll at the level printed on the information panel, in contained in) this product has been de- letters not larger than twice the size of termined by the U. Government to be the minimum type required for the unnecessary and inappropriate and declaration of net quantity of contents does not increase the dietary value of by §101. Labeling of the food," the blank to be filled in with noncomplying products may not in- the common or usual name of the nu- clude any such statement or otherwise trient(s) involved. It tween a product to which nutrient ad- could also result in deceptive or mis- dition has or has not been made in leading claims for certain foods. The order to meet the guideline, except Food and Drug Administration does that a nutrient addition shall be de- not encourage indiscriminate addition clared in the ingredient statement. Manufacturers kilocalories); contemplating using this principle are (2) The food is not the subject of any urged to contact the Food and Drug other Federal regulation for a food or Administration before implementing a class of food that requires, permits, or fortification plan based on this prin- prohibits nutrient additions; and ciple. I (4–1–10 Edition) (1) Is stable in the food under cus- added pursuant to paragraph (e) of this tomary conditions of storage, distribu- section. The (3) Potatoes, rice, or cereal-based following label claims are acceptable: product (other than bread or rolls) or (1) The labeling claim "fully restored another vegetable or vegetable mix- with vitamins and minerals" or "fully ture. Nutri- (i) It is inappropriate to make any ents used for such addition shall be bio- claim or statement on a label or in la- logically available in the final product. Final levels will be established when sufficient data are Subpart A—General Provisions available. Federal Food, Drug, and Cosmetic Act (3) When technologically practicable, (hereafter "the act") shall be applica- iodized salt shall be used or iodine ble with the following additions: shall be present at a level equivalent to (a)(1) The term special dietary uses, as that which would be present if iodized applied to food for man, means par- salt were used in the manufacture of ticular (as distinguished from general) the product. Technological addition of ited to the conditions of diseases, con- phosphates shall be minimized and valescence, pregnancy, lactation, aller- shall not exceed the amount necessary gic hypersensitivity to food, under- for the intended effect. I (4–1–10 Edition) of whether such food also purports to erals alone) purports to be or is rep- be or is represented for general use. The following definitions ent(s) in that ingredient is likely to be shall also apply: affected adversely by shipping or stor- (a) Indicator nutrient. An indicator age conditions, the manufacturer shall nutrient is a nutrient whose concentra- analyze that ingredient for each relied- tion is measured during the manufac- upon nutrient that may be affected, ture of an infant formula to confirm using validated analytical methods. An in-process scribed standards, shall be sampled and batch is a combination of ingredients analyzed for each relied-upon nutrient at any point in the manufacturing by the manufacturer, except that in- process before packaging. A manufacturer is a tein or fat need not be analyzed for person who prepares, reconstitutes, or each relied-upon nutrient if the manu- otherwise changes the physical or facturer has records to show that each chemical characteristics of an infant relied-upon nutrient is present at a formula and/or packages the product in reasonably constant level. A nutrient is any vita- mula manufacturer shall be sampled min, mineral, or other substance re- and analyzed for each relied-upon nu- quired in accordance with the table set trient. Nutrient premixes which are re- out in section 412(g) of the act or by ceived from suppliers shall be sampled regulations promulgated under section and analyzed for each relied-upon nu- 412(a)(2)(A) of the act.
If antibiotics are some of the oldest and most widely used medicines in the world buy slimex 10mg low cost, antiretrovirals are their opposites: new medicines 15 mg slimex for sale, prescribed in complicated regimes order 15mg slimex with amex, to a relatively small segment of the population purchase 15mg slimex otc. In 1995, during a meningitis epidemic, about 60,000 Nigeriens were injected with water disguised as meningitis vac- cine (Cockburn, 2005). More recently, in China, substandard hepatitis B and rabies vaccines killed or sickened about 100 babies (Jia and Carey, 2011). Precise infor- mation regarding the event is scarce due to the Chinese government’s denial of a connection between the vaccines and the incidents as well as its control over the Chinese media. According to the Associated Press, the original article in the China Economic Times that exposed the scan- dal stated that four children who died never had a precise diagnosis, but sufered from fevers and convulsions before their deaths; others who became ill were later diagnosed with encephalitis, among other conditions, and some sufered permanent damage (Associated Press, 2010a). About 200,000 doses of substandard rabies vaccine circulated in Jiangsu province in 2010 before a manufacturer recall (Associated Press, 2010b). These vaccines, like the falsifed meningitis vaccine used in Niger, convey no immunity to the patient. When herd immunity is an important result of vaccination, there is no such beneft to society. Assuming the patients survive injection with nonsterile, unidentifed liquids, they are still at risk for death from the disease they were not inoculated against. In September 2011, falsifed and substandard versions of the triple combination therapy Zidolam-N surfaced in Kenya, many samples molding and crumbling in the packages (Taylor, 2011). A year later, in Tanzania, the regulatory authority uncovered falsifed anti- retrovirals at a district hospital (Athumani, 2012). As their viral loads increase, these patients are also more likely to transmit the infection, impeding efforts to control the virus. Although data suggesting compromised antiretroviral drug quality are mixed, there is substantial evidence, presented in Chapter 3, that antima- larials are often of poor quality. Substandard and falsifed malaria drugs are especially common in malaria-endemic parts of Africa and Asia. In 2003, substandard sulfadoxine-pyrimethamine was used to treat a malaria epidemic in northwest Pakistan refugee camps (Leslie et al. Health workers diagnosed the parasite with microscopy, monitored drug resistance, and checked drug quality using procedures described in the U. Good care during initial infection and treatment with an effective second- line drug prevented any deaths, and the onset of cooler weather stopped transmission (Leslie et al. The prognosis for most people treated with poor-quality antimalarial drugs is worse. Not only will their malaria be untreated, but inadequate treatment favors the selection of resistant parasites, which threaten their entire communities. Treatment Failure Individual patients have much to lose from substandard and falsifed medicines. These products also encourage drug resistance and thereby threaten population health today and for future generations. This is a par- ticular concern with substandard products where the dose of active ingredi- ent is low and variable and with falsifed products diluted by criminals in an effort to pass screening assays. Drug resistance is common in pathogens with short life cycles: viruses, bacteria, and protozoa. Poor-quality anti- microbial medications, taken frequently and, in poor countries, generally taken without professional supervision, contribute to drug resistance. Poor-quality drugs have been cited as a causal factor for the rise of multidrug-resistant tubercu- losis (Kelland, 2012). Over time, the bacteria causing tuberculosis have be- come increasingly drug resistant. Multidrug-resistant tuberculosis precedes extensively drug-resistant tuberculosis, and fnally, sometimes, totally drug- resistant tuberculosis (Udwadia, 2012). Extensively drug-resistant strains of tuberculosis account for about 6 percent of incident infections worldwide, but much more in China, India, and the former Soviet Union (Jain and Mondal, 2008). Figure 2-1 shows the increasing incidence of multidrug- resistant tuberculosis around the world. Drug-resistant bacteria often surface in hospitals, causing infections that are diffcult to treat and are an important killer of adults in low- and middle-income countries (Okeke et al. It is diffcult to estimate the burden of antimicrobial resistance in low- and middle-income countries, in part because of the dearth of data, especially from francophone Africa, the Asian Pacifc, and the former Soviet Union (Okeke et al. Multidrug-resistant staphylococcus, an emerging problem in India and sub-Saharan Africa (Parasa et al. This is consistent with most public health literature, which gives great deal of attention to the overuse of antibiotics as contrib- uting to the rise of antimicrobial resistance in general (Byarugaba, 2010; Okeke et al. Comparatively little work, however, discusses the role of drug quality in encouraging bacterial resistance. Antibiotics that contain low doses of active ingredient cause low circulating levels of the drug in the patient. This contributes to treatment failure and selectively favors the growth of drug-resistant organisms (Okeke et al. Resistance is most common among the oldest and least expensive families of antibiotics (Okeke et al. Countering the Problem of Falsified and Substandard Drugs 64 Copyright © National Academy of Sciences. Antibiotics in particular offer pharmaceutical companies a low return on investment; pa- tients take them for only a week or two, in contrast to lifetime regimes of maintenance drugs. There would be even less monetary incentive to develop antibiotic for only the poorest parts of the world. Preserving antibiotics is imperative and depends on maintaining drug quality as much as on encour- aging rational use. Antimalarial Resistance Through a conceptually similar mechanism, selectively allowing the growth of drug-resistant parasites by exposing them to subtherapeutic doses of medicines, falsifed and substandard drugs favor survival and spread of resistance to antimalarial medicines. Drug-resistant parasites of particular concern are the malaria parasites Plasmodium falciparum and Plasmodium vivax. Drug resistance could undo the success that artemisinin therapies have won, however (see Box 2-3). A recent review estimates that about 35 per- cent of the antimalarial medicines in Southeast Asia are substandard, and 36 percent can be classifed as falsifed (Nayyar et al. The same researchers found similar patterns in sub-Saharan Africa, where about 35 percent of antimalarials are substandard and 20 percent are falsifed (Nayyar et al. In both regions, underdosing the active ingredients is far more common than overdosing (Nayyar et al. Already, 8 of the 12 major antimalarial drugs used in the world have been falsifed, including products labeled as of mefoquine, but containing sulphadoxine- pyrimethamine and no mefoquine, and a product labeled as artesunate, but containing 6 percent chloroquine and no artesunate (Newton et al. Poor-quality medicines supply a subtherapeutic dose that selectively encour- ages the emergence of partially resistant pathogens (Talisuna et al. Underdosing with antimalarials causes low concentrations of ac- tive drugs in patients and selective pressure to breed resistant parasites (Dondorp et al. In Thailand investigators have observed a progressive lengthening of the time it takes for patients to clear malaria parasites from their bloodstream dur- ing treatment, suggesting that the parasites are becoming more resistant to artemisinin (Phyo et al. Resistance is heritable from one generation Copyright © National Academy of Sciences.
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