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Wednesday, 15 February 2012

New Drug Approvals 2012 - Pt. VI - Tafluprost (ZioptanTM)



ATC code S01EE05
Wikipedia Tafluprost

On Feb 13th, 2012 FDA approved Tafluprost (trade name Zioptan) for treatment of elevated intraocular pressure in patients with open-angle glaucoma or ocular hypertension.
Tafluprost had been already available under the trade name Taflotan in Germany and Denmark from 2008, and under the trade name Saflutan in the United Kingdom and Spain from 2009.

Glaucoma is an eye disease associated with increased fluid pressure in the eye, eventually causing permament damage to the optic nerve, impairing the field of vision and ultimately leading to blindness. Glaucomas can be sub-classified as open-angle glaucoma (OAG) and closed-angle glaucoma (CAG), with OAG being a slowly progressive disease responsible for ~90% of glaucoma cases in the US, and CAG being an acute disease with rapid progression. Alongside various surgical forms of treatment, management of OAG usually consists of medication to lower intraocular pressure.

Tafluprost is a prostaglandin analogue (more specifically, a fluorinated analogue of prostaglandin F, acting as a prostaglandin receptor agonist) acting by increasing outflow of aequous humor. Similar dugs in the same class include Latanoprost, Bimatoprost and Travoprost. Alternative drug classes used for glaucoma include beta blockers which decrease aequous humor production. Tafluprost is dosed topically, i.e. as eye drops, and, unlike other prostaglandin analogs, is preservative-free, i.e. it does not contain benzalkonium chloride which may be harmful to sensitive eyes.

The molecular target of Tafluprost is the Prostaglandin F2-alpha receptor (UniProt:P43088, PTGFR), which is a rhodopsin-like GPCR (Pfam:PF00001).


>PF2R_HUMAN Prostaglandin F2-alpha receptor
MSMNNSKQLVSPAAALLSNTTCQTENRLSVFFSVIFMTVGILSNSLAIAILMKAYQRFRQ
KSKASFLLLASGLVITDFFGHLINGAIAVFVYASDKEWIRFDQSNVLCSIFGICMVFSGL
CPLLLGSVMAIERCIGVTKPIFHSTKITSKHVKMMLSGVCLFAVFIALLPILGHRDYKIQ
ASRTWCFYNTEDIKDWEDRFYLLLFSFLGLLALGVSLLCNAITGITLLRVKFKSQQHRQG
RSHHLEMVIQLLAIMCVSCICWSPFLVTMANIGINGNHSLETCETTLFALRMATWNQILD
PWVYILLRKAVLKNLYKLASQCCGVHVISLHIWELSSIKNSLKVAAISESPVAEKSAST




Tafluprost (PubChem 6433101) is a prodrug and derived from the natural product prostaglandin scaffold. It is an ester prodrug, for which cornea permeation is facilitated; esterases in the eye convert it to the active form, an acid. It has a molecular weight of 452.5 Da and is practically insoluble in water (computed logP (alogP): 4.33).
Its systematic name is isopropyl (5Z)-7-{(1R,2R,3R,5S)-2-[(1E)-3,3-difluoro-4-phenoxybut-1-en-1-yl]-3,5-dihydroxycyclopentyl}hept-5-enoate.
InChI=1S/C25H34F2O5/c1-18(2)32-24(30)13-9-4-3-8-12-20-21(23(29)16-22(20) 28)14-15-25(26,27)17-31-19-10-6-5-7-11-19/h3,5-8,10-11,14-15,18,20-23, 28-29H,4,9,12-13,16-17H2,1-2H3/b8-3+,15-14+.
Canonical Smiles=CC(C)OC(=O)CCC\C=C/C[C@H]1[C@@H](O)C[C@@H](O)[C@@H]1\C=C\C(F)(F)COc2ccccc2.

Zioptan contains 0.015 mg/mL tafluprost and is provided in single-use containers of 0.3 mL for once per day use, containing ~10 μmol of active ingredient per dose per eye, about 1% of which is absorbed by the eye. Mean plasma Cmax is around 26-27 pg/mL, and mean plasma AUC is around 394-432 pg·min/mL.
Common side effects include hyperaemia (i.e. red eyes), eye irritation or pain, headache, changes of pigmentation of the iris, eyelids, and eyelashes, and changes of length, thickness, shapes, and number of eyelashes. This side effect has led to off-label use of drugs of this class for primarily cosmetic purposes (there is now an approved PGF2R agonist for cosmetic use - Latisse).

Zioptan is marketed by Merck.

The product website can be found here, and the full prescribing information, here.

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