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Anti-parasitic drugs (抗寄生虫药) huifang Tang [email protected] Anti-parasitic drugs 1. Anti-malarial drugs(抗疟药) 2. Anti-schistosomiasis and antifilariasis drugs(抗血吸虫病和抗丝 虫病药) 3. Anti-amebiasis and antitricho-moniasis drugs(抗阿米巴 病和抗滴虫病药) 4. Anthelmintic drugs(抗肠蠕虫药) Part1 1. 疟药) Anti-malarial drugs(抗 Part1 Antimalarial drugs (抗疟药) •The malarial parasite(Plasmodium)(疟原虫), is a very small, single-cell blood organism. •It lives as a parasite in other organisms, namely man and mosquito. •The parasite is the cause of the tropical (热 带)disease malaria(疟疾). Anti-malarial drugs Anti-malarial drugs (抗疟药) 1. Biology of malarial parasite: (1)Classification of malaria: Human malaria is caused by 4 species of malarial parasite(plasmodium, 疟原虫), include: P. falciparum(恶性疟原虫), P. vivax(间日疟原虫), P. malariae(三日疟原虫), P. ovale(卵形疟原虫). Common malaria in our country are subtertian malaria(恶性疟) and tertian malaria(间日疟). The conditions of tertian malaria are milder, therefore, it is called benign malaria(良性疟) too. Anti-malarial drugs Parasite Life Cycle Anti-malarial drugs Antimalarial drugs - Drug Classification 1. Tissue schizonticides 组织裂殖体杀灭剂 eliminate developing or dormant liver forms(红外期裂殖 体); ---For control the prevention(预防) and relapse (复发) 2. Blood schizonticides 血裂殖体杀灭剂 act on erythrocytic parasites(红内期裂殖体); ---For control the symptom (症状) 3. Gametocides杀配子药 kill sexual stages and prevent transmission to mosquitoes. ---For control the communication(传播) Anti-malarial drugs (2)Life cycle of malarial parasite: Although malaria can be transmitted by transfusion of infected blood, human beings are infected more commonly by sporozoites(子孢子) injected by the bite of infected female mosquitoes. ①Asexual propagated stage in human body; ②Sexual propagated stage in female mosquitoes. Anti-malarial drugs ①Asexual propagated stage in human body: ▲Exo-erythrocytic stage: There are two types of sporozoites of tertian malaria(间日疟), that is: Tackysporozoite(速发型子孢子), and Bradysporozoite(迟发型子孢子). The tackysporozoites leave the circula-tion and localized in liver cells, then they rapidly transform, multiply and develop into schizonts(裂殖体) and merozoites(裂殖子). There are no symptoms in this stage. Anti-malarial drugs The bradysporozoites enter liver cells, then go into hypnozoite(休眠期), they become to dormancytes(休眠子), which is the source of tertian malaria relapse. Pyrimethamine(乙胺嘧啶) can kill tackysporozoites in the exo-erythrocytic stage. Primaquine(伯氨喹) can kill bradysporozoites to radically treat tertian malaria (间 日疟), and prevent tertian malaria rel-apse. Anti-malarial drugs ▲Erythrocytic stage: The schizonts(裂殖体) then rupture, each releasing thousands of merozoites (裂殖子), then enter the circulation and invade erythrocytes, initiate the eryth-rocytic stage, and transform trophozoite (滋养体) and schizonts, then release many merozoites. There are a lot of symptoms in this stage. Chloroquine(氯喹), Quinine(奎宁), and Artemisinin(青蒿素) are effective to this stage, they can control the symptoms, and prevent attack of malaria. Anti-malarial drugs ②Sexual propagated stage in female mosquitoes: Some erythrocytic malarial parasites differentiate into sexual forms known as gametocytes(配子体). The ♂ and ♀ gametocytes in the gut of the mosquito combine to thezygote(合子), which develops in the gut wall to in-fective sporozoites(子孢子), which invad-es salivary gland, become the source of infection. Pyrimethamine can inhibit the deve-lopment of ♂ and ♀ gametocytes in mos-quito to control transmission of malaria. Primaquine can kill various gameto-cytes of subtertian and tertian malaria. 氯喹 阿莫地喹 奎宁 奎尼丁 甲氟喹 伯氨喹 磺胺多辛-乙胺嘧啶 氯胍 多西环素 卤泛曲林 苯芴醇 青蒿素 阿托伐醌/氯胍 (马拉隆 ) Anti-malarial drugs Chloroquine(氯喹) •Chloroquine is a synthetic 4-aminoquinoline derivate Anti-malarial drugs Chloroquine Pharmacological effects 1. Antimalarial effects: erythrocytic stage •Rapid schizonticidal(裂殖体杀灭剂)activity against all infections of malaria species . •gametocytocidal(杀配子体)against P. vivax, P. malariae and P. ovale as well as immature gametocytes (stages 1-3) of P. falciparum. •The effects are fast and lasting. •The symptoms will vanish after oral administration of chloroquine in 24~48 h, blood malarial parasites disappear in 48 ~72 h, the recurrence rate in one month is low. Anti-malarial drugs Chloroquine Pharmacological effects 2. Immune inhibition •Treatment of rheumatoid arthritis, lupus erythematosus 3. Extraintestinal amebiasis •Amoeba trophozoite amebic liver abscess Anti-malarial drugs Chloroquine Mechanism of actions •Accumulation in erythrocyte→PH↑ → malarial pigment sythesis↓ •Haemoglobin-quinoline喹啉 compound → haemoglobin accumulate in plasmodium ↑ •Insert in the double stranded DNA helix → DNA replication and RNA transcription ↓ Anti-malarial drugs Chloroquine ADME of chloroquine: well absorbed after oral administration; Tmax = 3 ~ 5 hr, t½> 1 week; Widely distributed, the concentration in liver, lung, and kidney is higher 200 ~ 700 times than blood; The concentration in erythrocyte is higher 20 ~ 30 times than plasma; the concentration in infected erythrocyte by malarial parasite is higher 25 times than normal erythrocyte. Anti-malarial drugs Chloroquine Clinical uses: ①Malaria: ▲to control the symptoms of benign malaria(良性疟); ▲to cure subtertian malaria(恶性疟); ▲symptomatic prevention in epidemic area(疫 区的症状性预防). ②Amebiasis(阿米巴病): It can kill amebic trophozoite(滋养体), to treat systemic amebiasis(肠外阿米巴病), such as amebic hepatitis(阿米巴肝炎) and amebic hepatic abscess(阿米巴肝脓肿). ③Immune disease(免疫性疾病). Anti-malarial drugs Chloroquine Adverse reaction Rare at the usual antimalarial dosage Pruritus (搔痒症) common among dark-skinned people. Transient headaches, nausea, vomiting, gastrointestinal symptoms and "blurred vision“. Others: aplastic blood and neurological disorders, such as polyneuritis多发性神经炎, ototoxicity, seizures and neuromyopathy. Anti-malarial drugs Other angents kill erythrocytic parasites 1.Quinine 奎宁 2.Mefloquine甲氟喹 3.Pyronaridine 咯萘啶 4.Artemisinin青蒿素 5.Artemether and artesunate 蒿甲醚和青蒿琥酯 Quinine(奎宁) Anti-malarial drugs quinine Quinine is the chief alkaloid of cincho-na(金鸡纳), the bark of the South Ameri-can cinchona tree. (1)Anti-malarial action and clinical uses: Quinine acts primarily as a blood schizontocide(杀裂殖体药) to control the clini-cal symptoms; It is a gametocide for gametocytes(配子体) of P. vivax(间日疟原虫) & P. malariae(三日疟原虫) also, but not effective for game-tocytes of P. falciparum(恶性疟原虫). Anti-malarial drugs quinine Quinine is more toxic and less effective than chloroquine. but, it is especially valuable to treat: ①chloroquine-resistant and multidrugresistant subtertian malaria(耐氯喹和多药耐受的恶 性疟), ②severe cerebral malaria(严重的脑型疟). (2)Adverse reaction: more. ①Cinchonism(金鸡纳反应): ringing in the ears(耳鸣), headache, nausea, disturbed vision, etc. Anti-malarial drugs quinine ②Myocardial depression(心肌抑制作用): to reduce myocardial contractility, and slow down conduction and prolong refra-ctory period, but weaker than quinidine (奎尼丁, dextrogyre of quinine). ③Stimulating womb(兴奋子宫): can induce abortion, not to be take by pregnant woman. ④Idiosyncrasy(特异质反应): acute hemolytic reaction. Anti-malarial drugs mefloquine Mefloquine(甲氟喹) (1)Anti-malarial action: It is an efficient schizontocide in erythrocytic stage, effective to chloroquineresistant subtertian malaria. (2)Clinical uses: ①to treat chloroquine-resistant subter-tian malaria. ②to prevent and control the symptoms of benign malaria, once/two week. (3)Adverse reaction: GI reaction, nervous and pschic reaction. Anti-malarial drugs Artemisinin(Qinghaosu, 青蒿素) (1)Anti-malarial action: It is a highly efficient malariacide of schizonts in erythrocytic stage. The effects are faster than that of chloroquine, and effective to chloroquineresistant subtertian malaria, especially effective to cerebral malaria. (2)Clinical uses: to treat chloroquine-resistant subter-tian malaria, and to treat benign malaria also. but its recurrence rate is high. (3)Adverse reaction: less, GI reaction, occasionally serum GPT . Anti-malarial drugs primaquine Primaquine (伯氨喹) (1)Anti-malarial action: can kill dormancytes(休眠子) of tertian malaria and various gametocytes(配子体) of subtertian malaria. Owing to elimination fast, the effects are not lasting. Pharmacological effects Highly active against the gametocytes配子体 of all malaria species →dissemination ↓ Active against hypnozoites迟发型子孢子of the relapsing malarial parasites The only drug currently used for the treatment of relapsing malaria Anti-malarial drugs Antimalarial drugs - Pyrimethamine Pharmacological effects •Inhibition of proliferation of sporozoite子孢子 to schizont 裂殖体 •Prophylaxis of infections Mechanism of actions •Dihydrofolate reductase inhibitor Adverse effects •Folate metabolism disturbtance Anti-malarial drugs primaquine Antimalarial drugs - Primaquine (2)Mechanism of actions Inhibition of coenzyme Q Inhibition of reduction of NADP (3)Clinical uses: ①use it with chloroquine to radically treat benign malaria(良性疟); ②to prevent transmission of subtertian malaria(恶性疟). Anti-malarial drugs primaquine (3)Adverse reaction: Its toxicity is large nervous system :Transient dizziness , nausea, vomiting, gastrointestinal symptoms blood system:Acute hemolytic anemia((急性 溶血性贫血), methemoglobinemia高铁血红 蛋白血症 Anti-malarial drugs primethamine Pyrimethamine(乙胺嘧啶) (1)Anti-malarial action: ①It can kill schizonts(裂殖体) of subter-tian malarial parasites and benign mala-rial parasites in exo-erythrocytic stage; ②It can also kill immature schizonts of erythrocytic stage; ③It can not kill gametocytes(配子体), but can inhibit development of sporophytes(孢子体) in mosquito. Anti-malarial drugs primethamine (2)Clinical uses: It is mainly used to prevent malaria, the first chosen drug for malarial prev-ention. (3)Adverse reaction: Its toxicity is less. But long-term and larger dose administration, it can cause megaloblastic anemia(巨 红细胞贫血). This adverse reaction can be treated by formyl tetrahydrofolic acid(甲酰四氢叶酸). In addition, once large dose can cause acute intoxication. Anti-malarial drugs 3. Summarization: (1)Selection of antimalarial drugs: ①Symptom control: Chloroquine; ②Cerebral malaria: Artemisinin, im. Quinine dihydrochloride, iv gtt; ③Chloroquine-resistant subtertian malaria: Artemisinin, Quinine, Mefloquine; ④Resting stage: Pyrimethamine + Primaquine; ⑤Prevent transmission: Pyrimethamine. (2)Combined administration: Chloroquine + Primaquine; Pyrimethamine + Primaquine(防止复发). Part2 Anti-schistosomiasis drugs (抗血吸虫药) Schistosomiasis(血吸虫病) is caused by Schistosoma(血吸虫, 裂体吸虫) infection. There are five kinds of Schistosoma caused Schistosomiasis of human: S. japonia(日本血吸虫), S. heamatobium (埃 及血吸虫), S. mansoni(曼索血吸虫), S. intercalatum(间插血吸虫) and S. mekongi (湄公血 吸虫). In our country, the schistosomiasis is caused mainly by S. japonia. 肝硬化主征 巨 脾 腹 水 门脉高压 Anti-schistosomiasis drugs In the past, the drug treated schistosomiasis was PAT(酒石酸锑钾, potassium antimony tartrate), its course of treatment was longer, the toxicity larger, need iv administration, and the ADRs were severe. Since 1970’, praziquantel(吡喹酮) had be discovered, because its ADRs is less, praziquantel became the main drug to treat schistosomiasis. Anti-schistosomiasis drugs praziquantel Praziquantel(吡喹酮) (1)Anti-parasite effects: It is a highly effective and broad spec-trum anti-parasite drug. It can kill schistosoma(血吸虫) directly; and it can kill other trematde(吸虫) too, e.g. clonorchis sinensis(华支睾吸虫, 即“肝吸虫”), lung fluke(肺吸虫), fasciolopsis(布氏姜片虫, 即“肠 吸虫”); certain intestinal parasites(e.g. tapeworm(绦虫). Mechanism of anti-schistosoma effects: It can increase the membrane perme-ability to certain monovalent and dival-ent cation, particularly Ca2+, to cause schistosoma muscular contraction and spastic paralysis. Anti-schistosomiasis drugs praziquantel (2)Clinical uses: ①Schistosomiasis(血吸虫病): It is effective to both acute & chronic schistosomiasis. To acute schistosomiasis: It is to bring down the fever, and alleviate the systematic symptoms fast, the late results reach 90%; To chronic schistosomiasis: The curative effect is well too, only 1~2 days of course of treatment, the late results reach 90% too. To the later period patients with cardiac and hepatic complication: can accept the course of treatment smoothly. Anti-schistosomiasis drugs praziquantel ②Clonorchiasis(华枝睾吸虫病): It is the first-chosen drug. ③Other trematode(其他吸虫): Used to treat paragonimiasis(肺吸虫病) and fasciolopsiasis(姜片虫病). It is the first-chosen drug. ④Taeniasis(绦虫病): Including imago(成虫) & larva(幼虫) of various tapeworm(绦虫) infective disease, such as cysticercisis(囊虫症——猪囊虫尾蚴病) and hydatidosis(包虫病——由细粒棘球绦虫的幼虫引起). It is the first-chosen drug too. Anti-schistosomiasis drugs praziquantel (3)Adverse reaction less and lighter (than potassium anti-mony tartrate, 酒石酸锑钾). After oral administration, it can cause abdominal pain, nausea, dizziness, and headache in shortterm. C. anti-filariasis drugs (抗丝虫病药) Anti-filariasis drugs 下肢象皮肿 阴囊象皮肿 Anti-filariasis drugs Diethylcarbamazine 乙胺嗪 Pharmacology action Diethylcarbamazine immobilizes microfilariae(微丝蚴)and alters their surface structure, displacing them from tissues and making them more susceptible to destruction by host defense mechanisms. The mode of action against adult worms is unknown. Anti-filariasis drugs Diethylcarbamazine Adverse effects Generally mild and transient Include headache, malaise, anorexia, weakness, nausea, vomiting, and dizziness.