Tirofiban

Chemical properties

Tirofiban is an Off-White to Pale Yellow Solid. It is soluble in organic solvents such as ethanol, DMSO, and dimethyl formamide, which should be purged with an inert gas. The solubility of tirofiban in these solvents is approximately 30 mg/ml.

Originator

Aggrastat,Merck and Co., Inc.

The Uses of Tirofiban

Tirofiban (Aggrastatt, MK-0383; L-700,462) is a parenteral, highly specific, and potent GPIIb/IIIa antagonist that was approved for patient use in 1998 for the treatment of unstable angina and non-Q-wave myocardial infarction.
Tirofiban is a nonpeptide GP IIb/IIIa antagonist that binds reversibly to IIb/IIIa receptors. Tirofiban is a non-peptide reversible antagonist of the platelet integrin glycoprotein (GP) IIbIIIa receptor used as an antiplatelet drug.
Tirofiban is a small molecule inhibitor of the protein-protein interaction between fibrinogen and the platelet integrin receptor GP IIb/IIIa and is the first drug candidate whose origins can be traced to a pharmacophore-based virtual screening lead.

Background

Tirofiban prevents the blood from clotting during episodes of chest pain or a heart attack, or while the patient is undergoing a procedure to treat a blocked coronary artery. It is a non-peptide reversible antagonist of the platelet glycoprotein (GP) IIb/IIIa receptor, and inhibits platelet aggregation.

Indications

For treatment, in combination with heparin, of acute coronary syndrome, including patients who are to be managed medically and those undergoing PTCA or atherectomy.

Definition

ChEBI: Tirofiban is a member of the class of piperidines that is L-tyrosine in which a hydrogen attached to the amino group is replaced by a butylsulfonyl group and in which the hydrogen attached to the phenolic hydroxy group is replaced by a 4-(piperidin-4-yl)butyl group. It has a role as a fibrin modulating drug, a platelet glycoprotein-IIb/IIIa receptor antagonist and an anticoagulant. It is a member of piperidines, a sulfonamide and a L-tyrosine derivative.

Manufacturing Process

The synthesis of tirofiban starts by reaction of tyrosine with bis-trimethylsilyl trifluoraceramide to give a derivative in which both functions -OH and COOH_x0002_are protected. Treatment of this intermediate with butylsulfonyl chloride gives the corresponding sulfonamide derivative; the quite labile silyl groups are then removed under mildly acidic conditions to give N-butylsulfonyl-tyrosine. In a parallel scheme, 4-picoline is converted to its anion by means of butyl lithium; this gives 4-(4-chlorobutyl)-pyridine on alkylation with 1-bromo-3- chloropropane. The reaction of this compound with N-butylsulfonyl-tyrosine in presence of NaOH gives the ether 2-butylsulfonyaminol-3-[4-pyridin-4-ylbutoxy-phenyl]propionic acid. Hydrogenation over palladium on charcoal then reduce the pyridine ring to a piperidine to afford the fibrinogen receptor antagonist tirofiban.

Therapeutic Function

Fibrinogen receptor antagonist

General Description

Tirofiban is a nonpeptide that appears unrelatedchemically to eptifibatide, but actually has many similarities.The chemical architecture incorporates a systemthat is mimicking the RGD moiety that is present in eptifibatide.This can be seen in the distance between the nitrogenof the piperidine ring, which mimics the basic nitrogen ofarginine in the RGD sequence, and the carboxylic acid,which mimics the acid of aspartate in the RGD sequence.The basic nitrogen and the carboxylic acid of tirofiban areseparated by approximately 15 to 17? (16–18 atoms). Thisis the optimum distance seen in the RGD sequence of theplatelet receptor. Tirofiban is useful in treating non–Q wavemyocardial infarction and unstable angina.

Pharmacokinetics

Tirofiban prevents the blood from clotting during episodes of chest pain or a heart attack, or while the patient is undergoing a procedure to treat a blocked coronary artery. It is a non-peptide antagonist of the platelet glycoprotein (GP) IIb/IIIa receptor, and inhibits platelet aggregation. When administered intravenously, tirofiban inhibits ex vivo platelet aggregation in a dose- and concentration-dependent manner. When given according to the recommended regimen, >90% inhibition is attained by the end of the 30-minute infusion. Tirofiban has been recently shown in patients with unstable angina to reduce ischemic events at 48 hours following infusion when compared to standard heparin therapy.

Clinical Use

Tirofiban is a member of a new class of antithrombotic agents known as the “ fibans”. These compounds have a structural similarity to disintegrin, which was originally isolated from snake venoms. The location of the –COO- and NH3+ in the fibans is identical to the distance between the same functional groups of the RGD loop of disintegrin, and as a result, the fibans are able to effectively block the binding of fibrinogen to the GPIIb/IIIa receptor in an reversible manor.

Drug interactions

Potentially hazardous interactions with other drugs
Iloprost: increased risk of bleeding.
Heparin: increased risk of bleeding

Metabolism

Tirofiban is eliminated largely unchanged in the urine, with some biliary excretion in the faeces.

Metabolism

Metabolism appears to be limited.

Mode of action

Tirofiban is a reversible antagonist that inhibits platelet aggregation by reversibly binding to the receptor glycoprotein (GP) IIb/IIIa of human platelets, thus preventing the binding of fibrinogen. Inhibition of platelet aggregation occurs in a dose- and concentrationdependent manner.?