Tiotropium is a long–acting, antimuscarinic agent, which is often referred to as an anticholinergic. It has similar affinity to the subtypes of muscarinic receptors, M1 to M5. In the airways, it exhibits pharmacological effects through inhibition of M3–receptors at the smooth muscle leading to bronchodilation. The competitive and reversible nature of antagonism was shown with human and animal origin receptors and isolated organ preparations. In preclinical in vitro as well as in vivo studies prevention of methacholine–induced bronchoconstriction effects were dose–dependent and lasted longer than 24 hours. The bronchodilation following inhalation of tiotropium is predominantly a site–specific effect. Tiotropium is a muscarinic receptor antagonist, often referred to as an antimuscarinic or anticholinergic agent. Although it does not display selectivity for specific muscarinic receptors, on topical application it acts mainly on M3 muscarinic receptors located in the airways to produce smooth muscle relaxation, thus producing a bronchodilatory effect. Tiotropium is used in the management of chronic obstructive pulmonary disease (COPD).Tiotropium bromide capsules for inhalation are co-promoted by Boehringer-Ingelheim and Pfizer under the trade name Spiriva. It is also manufactured and marketed by Cipla under trade name Tiova.

Clofarabine is a anti-cancer drug which was approved by FDA for the treatment of pediatric patients with relapsed or refractory acute lymphoblastic leukemia. After crossing the cell membrane the drug is rapidly metabolized by deoxycytidine kinase to diphosphate and triphosphate metabolites and these metabolites reversibly inhibit hRNR by binding to alpha subunit. Also the triphosphate is incorporated to DNA where it acts as a chain terminator.

Atazanavir is the first once-daily protease inhibitor for the treatment of human immunodeficiency virus type 1 infection and should be used only in combination therapy, as part of a highly active antiretroviral therapy (HAART) regimen. In addition to being the most potent protease inhibitor in vitro, atazanavir has a distinct cross-resistance profile that does not confer resistance to other protease inhibitors. However, resistance to other protease inhibitors often confers clinically relevant resistance to atazanavir.

The potential antiviral effect of adefovir, an acyclic nucleoside phosphonate analog of 2′-deoxyadenosine monophosphate, was first studied by Holý and De Clercq in 1980s. Adefovir is an acyclic nucleotide analog of adenosine monophosphate which is phosphorylated to the active metabolite adefovir diphosphate by cellular kinases. Adefovir diphosphate inhibits HBV DNA polymerase (reverse transcriptase) by competing with the natural substrate deoxyadenosine triphosphate and by causing DNA chain termination after its incorporation into viral DNA. Oral adefovir dipivoxil is effective and generally well tolerated in HBeAg-positive and -negative patients chronically infected with wild-type or lamivudine-resistant HBV.

(R)-9-(2-Phosphonylmethoxypropyl)adenine (PMPA known as tenofovir) is an antiviral drug. Diphosphate of PMPA acts as a selective inhibitor of the HIV-1 reverse transcriptase. Tenofovir disoproxil was approved for clinical use for the treatment of HIV infection (AIDS) and chronic HBV infection.

(R)-9-(2-Phosphonylmethoxypropyl)adenine (PMPA known as tenofovir) is an antiviral drug. Diphosphate of PMPA acts as a selective inhibitor of the HIV-1 reverse transcriptase. Tenofovir disoproxil was approved for clinical use for the treatment of HIV infection (AIDS) and chronic HBV infection.

(R)-9-(2-Phosphonylmethoxypropyl)adenine (PMPA known as tenofovir) is an antiviral drug. Diphosphate of PMPA acts as a selective inhibitor of the HIV-1 reverse transcriptase. Tenofovir disoproxil was approved for clinical use for the treatment of HIV infection (AIDS) and chronic HBV infection.

(R)-9-(2-Phosphonylmethoxypropyl)adenine (PMPA known as tenofovir) is an antiviral drug. Diphosphate of PMPA acts as a selective inhibitor of the HIV-1 reverse transcriptase. Tenofovir disoproxil was approved for clinical use for the treatment of HIV infection (AIDS) and chronic HBV infection.

(R)-9-(2-Phosphonylmethoxypropyl)adenine (PMPA known as tenofovir) is an antiviral drug. Diphosphate of PMPA acts as a selective inhibitor of the HIV-1 reverse transcriptase. Tenofovir disoproxil was approved for clinical use for the treatment of HIV infection (AIDS) and chronic HBV infection.

(R)-9-(2-Phosphonylmethoxypropyl)adenine (PMPA known as tenofovir) is an antiviral drug. Diphosphate of PMPA acts as a selective inhibitor of the HIV-1 reverse transcriptase. Tenofovir disoproxil was approved for clinical use for the treatment of HIV infection (AIDS) and chronic HBV infection.