Cis-Platin

Abstract

Cis-Platin (cis-diamminedichloroplatinum(II)) is a platinum based drug used in medcine to treat many different types of cancers, including sarcomas carcinomars and lymphomars. PtCl₂(NH₃)₂ has 2 isomers; cis-PtCl₂(NH₃)₂ and trans-PtCl₂(NH₃)₂. Both compounds have a square planer geometry, and have been found not to isomerize at room temperature.

Physical properties

Empirical formula: PtCl₂(NH₃)₂

Molecular weight: 300.05 g/mol

Melting point: 270^oC

Cis-platin is a radioactive substance. It has a very short half life of only about 23 minutes.

Synthesis

Cis-platin is synthesised completely from potassium tetracloroplatinate which is comercially available, the first NH₃ group can be added to any of the four equivalent Cl gruops, but then the next NH₃ can be added either cis or trans to the first one, leading to 2 possible isomers. The trans directing nature of the Cl group (stronger than that of the NH₃ group) means that the cis-platin is favoured and formed more readily. In order to ensure more complete formation of cis-platin over trans-platin the potassium tetracloroplatinate is often converted to a tetraiodo compound before addition of the NH₃ group. This is to take advantage of the fact that Trans directing power of the halogens increases down the group, meaning that the iodoplatinate ill direct the NH₃ group cis to the other one more powerfully than the Chloroplatinate

Pharmacology

mode of action

Cis-platin works by interfacing with DNA and crosslinking the DNA in a number of different ways. This makes it impossible for the DNA to successfuly replicate itself. The drug must be administered in saline solution in order to work. The trans isomer does not have the same effect on DNA and as a result has no use as an anti-cancer drug.

Side Effects

Cis-platin has many side effects, and as a result of this its use is limited. The side effects can include: Kidney damage, nerve damage, nausea and vomiting, hair loss and also sometimes the loss of hearing.