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Antifungal Agents Antifungal Agents & & Antiviral drugs Antiviral drugs Huifang Tang [email protected]

Antifungal Agents & Antiviral drugs Huifang Tang [email protected]

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Page 1: Antifungal Agents & Antiviral drugs Huifang Tang tanghuifang@zju.edu.cn

Antifungal Agents Antifungal Agents & & Antiviral drugsAntiviral drugs

Huifang Tang [email protected]

Page 2: Antifungal Agents & Antiviral drugs Huifang Tang tanghuifang@zju.edu.cn

Part1 Part1 Antifungal AgentsAntifungal AgentsMycotic infections Categories:

deep mycosis(deep mycosis( 深部真菌病深部真菌病 )) ::(1)(1) vaginal candidiasis(vaginal candidiasis( 阴道念珠菌阴道念珠菌 ))(2)(2) histoplasm caspsulatum (histoplasm caspsulatum ( 组织胞浆菌组织胞浆菌 ))(3)(3) cryptococcal meningitis(cryptococcal meningitis( 隐球菌性脑膜炎隐球菌性脑膜炎 ))(4)(4) coccidioidomycosis(coccidioidomycosis( 球孢子菌病球孢子菌病 ))

superficial Mycosissuperficial Mycosis (浅部真菌病)(浅部真菌病) ::(1)(1) dermatophyte dermatophyte ((皮肤癣菌皮肤癣菌 )) infectionsinfections

Page 3: Antifungal Agents & Antiviral drugs Huifang Tang tanghuifang@zju.edu.cn

Categories

Antibiotic ( 抗生素类 ): Amphotericin B(Amphotericin B( 两性霉素 B ); Nystatin (制霉菌素) Griseofulvin(Griseofulvin( 灰黄霉素灰黄霉素 ))

Azole ( 唑类 ) : imidazoles (咪唑类): ketoconazole( 酮康唑 ), Tria

zoles (三唑类) : Itraconazole( 伊曲康唑 ), Allylamine( 丙烯胺类 ):

Terbinafine (特比萘芬) Pyrimidine ( 嘧啶类 ) :

Flucytosine ( 氟胞嘧啶 ) Echinocandins( 棘白菌素类 )

Caspofungin( 卡泊芬净 )

Page 4: Antifungal Agents & Antiviral drugs Huifang Tang tanghuifang@zju.edu.cn

MM echanism echanism of actionof action

Page 5: Antifungal Agents & Antiviral drugs Huifang Tang tanghuifang@zju.edu.cn

1. M1. Mechanism echanism of actionof action It It bind to ergosterol and alter membrane to allbind to ergosterol and alter membrane to all

ow leakage of cellular contents cause damage of ow leakage of cellular contents cause damage of cells.cells.

Amphotericin BAmphotericin BAmphotericin B

Page 6: Antifungal Agents & Antiviral drugs Huifang Tang tanghuifang@zju.edu.cn

Mechanism of Action

Amphotericin B is selective in its fungicidal effect because it exploits the difference in lipid composition of fungal and mammalian cell membranes.

Ergosterol, a cell membrane sterol, is found in the cell membrane of fungi, whereas the predominant sterol of bacteria and human cells is cholesterol.

Amphotericin B binds to ergosterol and alters the permeability of the cell by forming amphotericin Bassociated pores in the cell membrane .

Amphotericin B

Page 7: Antifungal Agents & Antiviral drugs Huifang Tang tanghuifang@zju.edu.cn

Antifungal Activity

broadest spectrum. Candida albicans and Cryptococcus neofor

mans( 白色念珠菌和新型隐球菌 ); endemic mycoses( 地方性真菌病 ): Histopla

sma capsulatum( 组织胞浆菌 ), Blastomyces dermatitidis( 皮炎芽生菌 ), and Coccidioides immitis (粗球孢子菌) ;

pathogenic molds (致病霉菌) , such as Aspergillus fumigatus ( 曲霉) and mucor(毛霉 ) .

Amphotericin B

Page 8: Antifungal Agents & Antiviral drugs Huifang Tang tanghuifang@zju.edu.cn

2. 2. Clinical usesClinical usesfungal infectionsfungal infections: : (1)(1) deep mycosis(deep mycosis( 深部真菌病深部真菌病 )) ::

(1)(1) vaginal candidiasis(vaginal candidiasis( 阴道念珠菌阴道念珠菌 ))(2)(2) histoplasm caspsulatum (histoplasm caspsulatum ( 组织胞浆菌组织胞浆菌 ))(3)(3) cryptococcal meningitis(cryptococcal meningitis( 隐球菌性脑膜炎隐球菌性脑膜炎

))(4)(4) coccidioidomycosiscoccidioidomycosis(( 球孢子菌病球孢子菌病 ))

(2)(2) superficial Mycosissuperficial Mycosis (浅部真菌病)(浅部真菌病) : : (1)(1) dermatophyte infectionsdermatophyte infections

Amphotericin B

Page 9: Antifungal Agents & Antiviral drugs Huifang Tang tanghuifang@zju.edu.cn

Pharmacokinetics

Amphotericin B is poorly absorbed from the gastrointestinal tract.

Oral amphotericin B is thus effective only on fungi within the lumen of the tract and cannot be used for treatment of systemic disease.

the drug is more than 90% bound by serum proteins amphotericin B is excreted slowly in the urine over a period of s

everal days. The serum t1/2 is approximately 15 days. Hepatic impairment, renal impairment, and dialysis have little i

mpact on drug concentrations, and therefore no dose adjustment is required.

The drug is widely distributed in most tissues, but only 2–3% of the blood level is reached in cerebrospinal fluid, thus occasionally necessitating intrathecal therapy for certain types of fungal meningitis.

Amphotericin B

Page 10: Antifungal Agents & Antiviral drugs Huifang Tang tanghuifang@zju.edu.cn

Adverse Effects The toxicity of amphotericin B can be divided into two broad categori

es: INFUSION-RELATED TOXICITY

Fever, chills, muscle spasms, vomiting, headache, and hypotension.

They can be ameliorated by slowing the infusion rate or decreasing the daily dose.

Premedication with antipyretics, antihistamines, meperidine, corticosteroids can be helpful.

CUMULATIVE TOXICITY Renal damage is the most significant toxic reaction. Abnormalities of liver function tests are occasionally seen. After intrathecal therapy ( 鞘内注射 )with amphotericin, seizur

es and a chemical arachnoiditis( 蛛网膜炎 ) may develop, often with serious neurologic sequelae.

Amphotericin B

Page 11: Antifungal Agents & Antiviral drugs Huifang Tang tanghuifang@zju.edu.cn

Liposomal amphotericin B liposomal amphotericin B (AmBisome , 脂质

体) amphotericin B colloidal dispersion(ABCD,

胶样分散体 ) amphotericin B lipid complex ( ABLC, 脂质

复合物)

Amphotericin B

Page 12: Antifungal Agents & Antiviral drugs Huifang Tang tanghuifang@zju.edu.cn

Nystatin (制霉菌素) Nystatin is a polyene macrolide much like amphotericin B. It is

too toxic for parenteral administration (肠外给药 ) and is only used topically.

Nystatin is currently available in creams, ointments, suppositories, and other forms for application to skin and mucous membranes.

It is not absorbed to a significant degree from skin, mucous membranes, or the gastrointestinal tract. As a result, nystatin has little toxicity, although oral use is often limited by the unpleasant taste.

Nystatin is active against most Candida sp and is most commonly used for suppression of local candidal infections.

Some common indications include oropharyngeal thrush (鹅口疮) , vaginal candidiasis, and intertriginous candidal infections.

Page 13: Antifungal Agents & Antiviral drugs Huifang Tang tanghuifang@zju.edu.cn

Griseofulvin(Griseofulvin( 灰黄霉素灰黄霉素 ))

(1) (1) Mechanism of action :: cellular level Binds to microtubules and prevents mitosis in fungi. Binds to microtubules and prevents mitosis in fungi. it is deposited in newly forming skin where it binds to keratin (角质 ) , protec

ting the skin from new infection. Because its action is to prevent infection of these new skin structures, griseofulvin must be administered for 2–6 weeks for skin and hair infections to allow the replacement of infected keratin by the resistant structures.

Nail infections may require therapy for months to allow regrowth of the new protected nail and is often followed by relapse.

(2) (2) Clinical usesClinical uses:: Oral long-term therapy for dermatophyteOral long-term therapy for dermatophyte,, hair and nail infections hair and nail infections(( 33 )) Adverse effectsAdverse effects

An allergic syndrome much like serum sickness( 血清病 ), hepatitis, drug interactions with warfarin and phenobarbital.

Page 14: Antifungal Agents & Antiviral drugs Huifang Tang tanghuifang@zju.edu.cn

Azoles (唑类) imidazoles (咪唑类) :

ketoconazole( 酮康唑酮康唑 ), Miconazole( 咪康唑咪康唑 ), clotrimazole ( 克霉唑克霉唑 )

Triazoles (三唑类) : Itraconazole( 伊曲康唑 ), Fluconazole( 氟康唑 ), Voriconazole(伏立康唑 ), Posaconazole( 泊沙康唑 ).

Azoles

Page 15: Antifungal Agents & Antiviral drugs Huifang Tang tanghuifang@zju.edu.cn

Mechanism of Action

The antifungal activity of azole drugs results from the reduction of ergosterol synthesis by inhibition of fungal cytochrome P450 enzymes.

The selective toxicity of azole drugs results from their greater affinity for fungal than for human cytochrome P450 enzymes.

Imidazoles exhibit a lesser degree of selectivity than the triazoles, accounting for their higher incidence of drug interactions and side effects.

Resistance to azoles occurs via multiple mechanisms.

Azoles

Page 16: Antifungal Agents & Antiviral drugs Huifang Tang tanghuifang@zju.edu.cn

Pharmacokinetics

Azoles

Page 17: Antifungal Agents & Antiviral drugs Huifang Tang tanghuifang@zju.edu.cn

Clinical Use

The spectrum of action of azole medications is broad, including many candida species( 念珠菌 ), C neoformans( 新型隐球菌 ), the endemic mycoses ( 地方性真菌病 )(blastomycosis( 芽生菌 ), coccidioidomycosis( 球孢子菌病 ), histoplasmosis( 组织胞浆菌病 )), the dermatophytes( 皮肤癣菌 ), and, in the case of itraconazole and voriconazole, even aspergillus infections( 曲霉菌感染 ).

They are also useful in the treatment of intrinsically amphotericin-resistant organisms such as P boydii.

Azoles

Page 18: Antifungal Agents & Antiviral drugs Huifang Tang tanghuifang@zju.edu.cn

Adverse Effects

the azoles are relatively nontoxic. The most common adverse reaction is relatively minor gastrointestinal upset.

All azoles have been reported to cause abnormalities in liver enzymes and, very rarely, clinical hepatitis.

All azole drugs affect the mammalian cytochrome P450 system of enzymes to some extent, and consequently they are prone to drug interactions.

Azoles

Page 19: Antifungal Agents & Antiviral drugs Huifang Tang tanghuifang@zju.edu.cn

Ketoconazole(酮康唑 ) Ketoconazole was the first oral azole introduced into c

linical use. greater propensity to inhibit mammalian cytochrome

P450 enzymes less selective for fungal P450 than newer azoles. Clinical Clinical UsesUses: : 1. C1. Cutaneous candidiasis(utaneous candidiasis( 皮肤念珠菌病皮肤念珠菌病 )): : vagivagi

nal nal 2. 2. Dermatophytosis(Dermatophytosis( 皮肤癣菌病 ))3. 3. histoplasmosis(histoplasmosis( 组织胞浆菌病组织胞浆菌病 ))

Azoles

Page 20: Antifungal Agents & Antiviral drugs Huifang Tang tanghuifang@zju.edu.cn

Itraconazole(伊曲康唑 ) Itraconazole is available in oral and intravenous formulations.

Drug absorption is increased by food and by low gastric pH. Like other lipid-soluble azoles, it interacts with hepatic microsomal enzymes, though to a lesser degree than ketoconazole.

Like ketoconazole, it penetrates poorly into the cerebrospinal fluid. Itraconazole is the azole of choice for treatment of disease due to the dimorphic fungi histoplasma( 组织胞浆菌 ), Blastomyces( 芽生菌 ), and sporothrix( 孢子丝菌 ).

Itraconazole has activity against Aspergillus sp, but it has been replaced by voriconazole as the azole of choice for aspergillosis( 曲霉菌病 ).

Itraconazole is used extensively in the treatment of dermatophytoses( 皮肤癣菌 )and onychomycosis( 甲癣 ).

Azoles

Page 21: Antifungal Agents & Antiviral drugs Huifang Tang tanghuifang@zju.edu.cn

Fluconazole(氟康唑 ) Fluconazole displays a high degree of water solubility and go

od cerebrospinal fluid penetration, its oral bioavailability is high.

The drug is available in oral and intravenous formulations. Drug interactions are also less common because fluconazole

has the least effect of all the azoles on hepatic microsomal enzymes. Because of fewer hepatic enzyme interactions and better gastrointestinal tolerance, fluconazole has the widest therapeutic index of the azoles, permitting more aggressive dosing in a variety of fungal infections.

Fluconazole displays no activity against aspergillus( 曲霉菌 ) or other filamentous fungi( 丝状真菌 ).

Clinical use cryptococcal meningitis( 隐球菌性脑膜炎 ). Mucocutaneous candidiasis( 皮肤粘膜念珠菌病 ). Coccidioidal disease( 球孢子菌病 )

Azoles

Page 22: Antifungal Agents & Antiviral drugs Huifang Tang tanghuifang@zju.edu.cn

Voriconazole(伏立康唑 ) Voriconazole is available in intravenous and oral formulations. The dr

ug is well absorbed orally, with a bioavailability exceeding 90%, and it exhibits less protein binding than itraconazole.

Metabolism is predominantly hepatic. Voriconazole is a clinically relevant inhibitor of mammalian CYP3A4.

Adverse Effects Observed toxicities include rash and elevated hepatic enzymes. Visual disturbances are common, occurring in up to 30% of patients r

eceiving intravenous voriconazole, and include blurring and changes in color vision or brightness. These visual changes usually occur immediately after a dose of voriconazole and resolve within 30 minutes.

Photosensitivity dermatitis is commonly observed in patients receiving chronic oral therapy.

spectrum of action excellent activity against Candida sp (假丝菌) (including fluconazol

e-resistant species such as C krusei) and the dimorphic fungi (双相真菌)。

Azoles

Page 23: Antifungal Agents & Antiviral drugs Huifang Tang tanghuifang@zju.edu.cn

Posaconazole( 泊沙康唑 ) Posaconazole is the newest triazole to be licensed in the USA. I

t is available only in a liquid oral formulation. Posaconazole is rapidly distributed to the tissues, resulting in h

igh tissue levels but relatively low blood levels. Posaconazole is the broadest spectrum member of the azole fa

mily, with activity against most species of candida ( 念珠菌 )and aspergillus( 曲霉 ).

It is the only azole with significant activity against the agents of zygomycosis and mucormycosis( 毛霉菌病 ).

Clinical use Salvage therapy in invasive aspergillosis( 侵袭性曲霉病 ), prophylaxis of fungal infections during induction chemotherap

y for leukemia, allogeneic bone marrow transplant patients with graft-versus-host disease( 异基因骨髓移植患者的移植物抗宿主病 ).

Azoles

Page 24: Antifungal Agents & Antiviral drugs Huifang Tang tanghuifang@zju.edu.cn

Echinocandins (棘白菌素类) Echinocandins are the newest class of antifungal agents to b

e developed. They are large cyclic peptides linked to a long-chain fatty acid.

Caspofungin( 卡泊芬净 ) , micafungin( 米卡芬净 ), and anidulafungin (阿尼芬净) are the only licensed agents in this category of antifungals, although other drugs are under active investigation.

Echinocandins are available only in intravenous formulations.

These agents are active against candida and aspergillus, but not C neoformans or the agents of zygomycosis and mucormycosis.

Mechanism of Action Echinocandins act at the level of the fungal cell wall by inhib

iting the synthesis of (1–3)-glucan.

Echinocandins

Page 25: Antifungal Agents & Antiviral drugs Huifang Tang tanghuifang@zju.edu.cn

Pharmacokinetics

Caspofungin (卡泊芬净) is water-soluble and highly protein-bound. The half-life is 9–11 hours, and the metabolites are excreted by the kidneys and gastrointestinal tract. Dosage adjustments are required only in the presence of severe hepatic insufficiency.

Micafungin (米卡芬净) displays similar properties with a half-life of 11–15 hours for treatment of candida esophagitis, candidemia, and prophylaxis of fungal infections.

Anidulafungin (阿尼芬净) has a half-life of 24–48 hours. For esophageal candidiasis, it is administered intravenously at 100 mg on the first day and 50 mg/d thereafter for 14 days. For candidemia, a loading dose of 200 mg is recommended with 100 mg/d thereafter for at least 14 days after the last positive blood culture.

Echinocandins

Page 26: Antifungal Agents & Antiviral drugs Huifang Tang tanghuifang@zju.edu.cn

Adverse Effects

Echinocandin agents are extremely well tolerated, with minor gastrointestinal side effects and flushing reported infrequently.

Elevated liver enzymes have been noted in several patients receiving caspofungin in combination with cyclosporine, and this combination should be avoided.

Micafungin has been shown to increase levels of nifedipine, cyclosporine, and sirolimus. Anidulafungin does not seem to have significant drug interactions, but histamine release may occur during intravenous infusion.

Echinocandins

Page 27: Antifungal Agents & Antiviral drugs Huifang Tang tanghuifang@zju.edu.cn

Clinical Use

Caspofungin is currently licensed for disseminated and mucocutaneous candida infections (侵袭性和皮肤粘膜念珠菌病)

Note that caspofungin is licensed for use in invasive aspergillosis (侵袭性曲霉病) only as salvage therapy in patients who have failed to respond to amphotericin B, and not as primary therapy.

Micafungin is licensed for mucocutaneous candidiasis, candidemia, and prophylaxis of candida infections in bone marrow transplant patients.

Anidulafungin is approved for use in esophageal candidiasis and invasive candidiasis, including candidemia.

Echinocandins

Page 28: Antifungal Agents & Antiviral drugs Huifang Tang tanghuifang@zju.edu.cn

Mechanism of ActionMechanism of Action Flucytosine is taken up by fungal cells via the Flucytosine is taken up by fungal cells via the enzyenzy

me cytosine permeaseme cytosine permease. It is converted intracellula. It is converted intracellularly first to 5-FU and then to 5-rly first to 5-FU and then to 5-

fluorodeoxyuridine monophosphate (FdUMP) and flufluorodeoxyuridine monophosphate (FdUMP) and fluorouridine triphosphate (FUTP), which inhibit DNorouridine triphosphate (FUTP), which inhibit DNA and RNA synthesis, respectively.A and RNA synthesis, respectively.

Human cells are unable to convert the parent drug tHuman cells are unable to convert the parent drug to its active metabolites, resulting in selective toxio its active metabolites, resulting in selective toxicity.city.

Clinical usesClinical uses::

Rarely used as a single drug but often used in combinatioRarely used as a single drug but often used in combination with other antifungal agents n with other antifungal agents

FlucytosineFlucytosine ( ( 氟胞嘧啶氟胞嘧啶 ))

Page 29: Antifungal Agents & Antiviral drugs Huifang Tang tanghuifang@zju.edu.cn

Allylamine (丙胺类)Terbinafine (特比萘芬)

Terbinafine is a synthetic allylamine that is available in an oral formulation. I

t is used in the treatment of dermatophytoses, especially onychomycosis ( 灰指甲 ). it is fungicidal.

it interferes with ergosterol biosynthesis, but rather than interacting with the P450 system, terbinafine inhibits the fungal enzyme squalene epoxidase ( 角鲨烯环氧化酶 ). This leads to the accumulation of the sterol squalene (甾醇角鲨烯) ,which is toxic to the organism.

Adverse effects : rare primarily of gastrointestinal upset and headache. Terbinafine does not seem to affect the P450 system and

has demonstrated no significant drug interactions to date.

Page 30: Antifungal Agents & Antiviral drugs Huifang Tang tanghuifang@zju.edu.cn
Page 31: Antifungal Agents & Antiviral drugs Huifang Tang tanghuifang@zju.edu.cn

合成病毒核酸 \ 蛋白

病毒颗粒装配成熟(assembly)

合成核酸多聚酶

病毒脱壳 (uncoating)

病毒吸附侵入(attachment & penetration)

从细胞内释放 (release)

Part2 Antiviral drugsPart2 Antiviral drugs

Page 32: Antifungal Agents & Antiviral drugs Huifang Tang tanghuifang@zju.edu.cn

Antiviral therapy

肝炎病毒

艾滋病毒

疱疹病毒流感病毒 Influenza—RNA virus

herpesviruses (HSV)—DNA virus

human immunodeficiency virus (HIV)- RNA Reverse transcript virus

Page 33: Antifungal Agents & Antiviral drugs Huifang Tang tanghuifang@zju.edu.cn

Antiviral drugs Anti-influenza virus agents

Amantadine( 金刚烷胺 )--influenza A Target: viral protein, M2

Oseltamivir( 奥赛他米韦 ) ; zanamivir (扎那米韦) --influenza A &B Target: neuraminidase( 神经氨酸酶 ) inhibitors

Antiherpes agents idoxuridine( 碘苷 ) -- HSV, VZV Vidarabine(阿糖腺苷 )—HSV,VZV,HBV,CMV acyclovir (阿昔洛韦) ; ganciclovir( 更昔洛韦 ) ; valacyclovir( 伐昔洛

韦 ) foscarnet (磷甲酸盐) --HSV, influenza ,CMV, HIV cidofovir ( 西多福韦 )—HSV,VZV,CMV

Page 34: Antifungal Agents & Antiviral drugs Huifang Tang tanghuifang@zju.edu.cn

Anti-HIV agents Entry inhibitors( 入胞抑制药 ) Reverse transcriptase inhibitor( 逆转录酶抑制剂 )

nonnucleoside reverse transcriptase inhibitor( 非核苷逆转录酶抑制剂 , NNRTI);

nucleoside reverse transcriptase inhibitor( 核苷逆转录酶抑制剂 , NRTI);

Protease inhibitor( 蛋白酶抑制剂 ,PI) Integrase Inhibitors (整合酶抑制药)

Page 35: Antifungal Agents & Antiviral drugs Huifang Tang tanghuifang@zju.edu.cn

MechanismMechanism of of Antiviral drug actionAntiviral drug action

病毒吸附病毒侵入

病毒脱壳

合成病毒核酸 \ 蛋白质

病毒颗粒装配成熟

释放

Page 36: Antifungal Agents & Antiviral drugs Huifang Tang tanghuifang@zju.edu.cn

1 Anti-influenza virus agents

Amantadine( 金刚烷胺 ) The mechanism of Amantadine's antiviral activity involves interfer

ence with a viral protein, M2 (an ion channel), which is required for the viral particle to become "uncoated" once taken inside a cell by endocytosis.

The mechanism of its antiparkinsonian effect is poorly understood. The drug has many effects in the brain, including release of dopamine and norepinephrine from nerve endings. It appears to be a weak NMDA receptor antagonist as well as an anticholinergic.

Clinical useClinical use(1) Preventing influenza A infections during influenza season(1) Preventing influenza A infections during influenza season(2) Parkinson's disease(2) Parkinson's disease(3) Off-label uses(3) Off-label usesSide effects:Side effects:((1)CNS side effects include nervousness, anxiety, agitation, insomnia, difficulty in concentratin1)CNS side effects include nervousness, anxiety, agitation, insomnia, difficulty in concentratin

g, and exacerbations of pre-existing seizure disorders and psychiatric symptoms in patientg, and exacerbations of pre-existing seizure disorders and psychiatric symptoms in patients with schizophrenia or Parkinson's disease. s with schizophrenia or Parkinson's disease.

(2)Rare cases of severe skin rashes such as Stevens Johnson Syndrome(2)Rare cases of severe skin rashes such as Stevens Johnson Syndrome and suicidal ideation.and suicidal ideation.(3) (3) Livedo reticularis ( ( 网状青斑网状青斑 ) is a possible side effect of amantadine use for Parkinson's disea) is a possible side effect of amantadine use for Parkinson's disea

se.se.

Page 37: Antifungal Agents & Antiviral drugs Huifang Tang tanghuifang@zju.edu.cn

2. Antiherpes agents

Herpessimplexvirus (疱疹病毒, HSV )

Varicella-zoster virus ( 水痘 /带状疱疹病毒, VZV)

Cytomegalovirus( 巨细胞病毒 CMV)

碘苷 (idoxuridine) 阿昔洛韦( acyclovir ) 更昔洛韦 (ganciclovir) 伐昔洛韦 (valacyclovir) 磷甲酸盐( foscarnet) 西多福韦 (cidofovir) 屈氟尿苷 (trifluridine)

胸苷激酶

Page 38: Antifungal Agents & Antiviral drugs Huifang Tang tanghuifang@zju.edu.cn

IdoxuridineIdoxuridine (( 碘苷碘苷 )) Its main use is in treatment of herIts main use is in treatment of her

pes simplex and varicelly-zoster pes simplex and varicelly-zoster infections in eye. infections in eye.

Being too toxic for systemic use, it Being too toxic for systemic use, it is only used topically.is only used topically.

Page 39: Antifungal Agents & Antiviral drugs Huifang Tang tanghuifang@zju.edu.cn

Acyclovir(Acyclovir(阿昔洛韦阿昔洛韦 ,,无环鸟无环鸟苷苷 )) 1. M1. Mechanism echanism of actionof action It inhibits viral DNA-polymerase, terminating the DNA-

chain. . clinical activity --HSV-1, HSV-2, and VZV, but it is

approximately 10 times more potent against HSV-1 and HSV-2 than against VZV.

In vitro activity -- Epstein-Barr virus (EBV), cytomegalovirus (CMV), and human herpesvirus-6 (HHV-6) is present but weaker.

2. Clinical use:2. Clinical use:The bioavailability of oral acyclovir is low (15–20%) and is uThe bioavailability of oral acyclovir is low (15–20%) and is u

naffected by food. An intravenous formulation is availablnaffected by food. An intravenous formulation is available.e.

It is used to treat herps simplex viruses, varicella-zoster viruses.

First choice --Herpes simplex viruses infection.

ValganciclovirAntiviral drugs2

Page 40: Antifungal Agents & Antiviral drugs Huifang Tang tanghuifang@zju.edu.cn

Ganciclovir( 更昔洛韦 ) Initial phosphorylation is catalyzed by the virus-

specified protein kinase phosphotransferase UL97 in CMV-infected cells.

The activated compound competitively inhibits viral DNA polymerase and causes termination of viral DNA elongation.

Ganciclovir has in vitro activity against CMV, HSV, VZV, EBV, HHV-6, and HHV-8.

Its activity against CMV is up to 100 times greater than that of acyclovir.

ValganciclovirAntiviral drugs2

Page 41: Antifungal Agents & Antiviral drugs Huifang Tang tanghuifang@zju.edu.cn

Valganciclovir( 伐昔洛韦 ) Valganciclovir is an L-valyl ester prodrug of ganciclovir that exists as a mixtu

re of two diastereomers. After oral administration, both diastereomers are rapidly hydrolyzed to ganc

iclovir by intestinal and hepatic esterases. Valganciclovir is well absorbed and rapidly metabolized in the intestinal wall

and liver to ganciclovir; The absolute bioavailability of oral valganciclovir is 60%. The AUC0–24h resu

lting from valganciclovir (900 mg once daily) is similar to that after 5 mg/kg once daily of intravenous ganciclovir and approximately 1.65 times that of oral ganciclovir.

The major route of elimination is renal, through glomerular filtration and active tubular secretion.

Clinical use Cytomegalovirus(CMV) retinitis in patients with AIDS prevention of CMV disease in high-risk kidney, heart, and kidney-pancreas tr

ansplant patients.

ValganciclovirAntiviral drugs2

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Ribavirin(利巴韦林)

(1) (1) Action: It is effective against a broad spectrum of RNA and DNA viruses.

(2) (2) Uses: It is used in treating infants and young children infected with severe respiratory syncytial virus ( 呼吸道合胞病毒 RSV)infections, actue hepatitis A virus, and influenza A and B infections.

Ribavirin

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Foscarnet(磷甲酸盐 )

It has in vitro activity against HSV, VZV, CMV, EBV, HHV-6( 人类疱疹病毒 ), HHV-8, and HIV-1. inhibits viral DNA polymerase, inhibits RNA polymerase, inhibits HIV reverse transcriptase

Foscarnet blocks the pyrophosphate binding site of these enzymes and inhibits cleavage of pyrophosphate from deoxynucleotide triphosphates.

Foscarnet is available in an intravenous formulation only;

Foscarnet

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Adverse effects Renal impairment, hypo- or

hypercalcemia, hypo- or hyperphosphatemia, hypokalemia, and hypomagnesemia.

Nausea, vomiting, anemia, elevation of liver enzymes, and fatigue

the risk of anemia may be additive in patients receiving concurrent zidovudine.

Central nervous system toxicities include headache, hallucinations, and seizures;

Foscarnet caused chromosomal damage in preclinical studies.

Foscarnet

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Anti-HIV agents summary

Entry inhibitors( 入胞抑制药 )

恩夫韦地( enfuvrtide )西夫韦肽( sifuvirtide )

马拉韦罗( maraviroc )

NNRTI:地拉韦定 (delavirdine)奈韦拉平 (nevirapine)依法韦恩茨 (efavirenz)

NRTI: 齐多夫定 (zidovudine , AZT)扎西他宾 (zalcitabine , ddC)司他夫定 (stavudine , d4T)拉米夫定 (lamivudine , 3TC)去羟肌苷 (didanosine , ddI)阿巴卡韦 (abacavir , ABC)

Protease inhibitor( 蛋白酶抑制剂 ,PI)

利托那韦 (ritonavir) 奈非那韦 (nelfinavir) 沙奎那韦 (saquinavir) 英地那韦 (indinavir) 安谱那韦 (amprenavir)

Integrase Inhibitors (整合酶抑制药) :雷特格韦( raltegravir )

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Zidovudine( 齐多夫定 ,zdv,azt) Zidovudine (azidothymidine; AZT) is a deoxythy

midine analog that is well absorbed (63%) and distributed to most body tissues and fluids, including thecerebrospinal fluid, where drug levels are 60–65% of those in serum.

the serum half-life averages 1.1 hours, the intracellular half-life of the phosphorylated compound is 3–4 hours, allowing twice-daily dosing.

Zidovudine is eliminated primarily by renal excretion following glucuronidation in the liver.

Zidovudine

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Zidovudine is often co-administered with lamivudine, and a combination formulation is available.

Zidovudine was the first antiretroviral agent to be approved and has been well studied. The drug has been shown to decrease the rate of clinical disease progression and prolong survival in HIV-infected individuals.

Efficacy has also been demonstrated in the treatment of HIV-associated dementia and thrombocytopenia. In pregnancy, a regimen of oral zidovudine beginning between 14 and 34 weeks of gestation, intravenous zidovudine during labor, and zidovudine syrup to the neonate from birth through 6 weeks of age has been shown to reduce the rate of vertical (mother-to-newborn) transmission of HIV by up to 23%.

Zidovudine

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Adverse effect myelosuppression, resulting in macrocytic anemia (1–4%) or neutropenia (2

–8%). Gastrointestinal intolerance, headaches, and insomnia may occur but tend to resolve during therapy.

Extremity fat loss may be more common with zidovudine than with other agents.

Less common toxicities include thrombocytopenia, hyperpigmentation of the nails, and myopathy. High doses can cause anxiety, confusion, and tremulousness.

Zidovudine causes vaginal neoplasms in mice; however, no human cases of genital neoplasms have been reported to date. Short-term safety has been demonstrated for both mother and infant.

Increased serum levels of zidovudine may occur with concomitant administration of probenecid, phenytoin, methadone, fluconazole, atovaquone, valproic acid, and lamivudine, either through inhibition of first-pass metabolism or through decreased clearance.

Zidovudine may decrease phenytoin levels. Hematologic toxicity may be increased during co-administration of other myelosuppressive drugs such as ganciclovir, ribavirin, and cytotoxic agents. Combination regimens containing zidovudine and stavudine should be avoided due to in vitro antagonism

Zidovudine

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