Reference
Where the six locks were made
None of these six arrived as a finished postcard. These are the labs that found them, the clinics that tested them, and the regulators that set the limits.
Pfizer, Sandwich (discovery site)
Ramsgate Road, Sandwich, Kent CT13 9NJ, United Kingdom
Sildenafil started life here as UK-92,480, a hopeful angina candidate. Its numbers for chest pain were unremarkable; a side effect volunteers kept mentioning was anything but, and the programme was redrawn around it. Viagra, and the whole PDE5 family that followed, traces back to this Kent laboratory.
ICOS Corporation with Eli Lilly
22021 20th Avenue SE, Bothell, WA 98021, USA
Tadalafil was identified at this Washington biotech and carried through late trials with Eli Lilly. Its defining feature was written into the pharmacokinetics rather than the chemistry: it leaves the body far more slowly than its rivals, which is why a genuinely long-acting tablet — and later a low daily dose — became possible at all.
Bayer, Wuppertal
Aprather Weg 18a, 42113 Wuppertal, Germany
The Wuppertal laboratories developed vardenafil, later sold as Levitra and the orodispersible Staxyn. Milligram for milligram it binds PDE5 more tightly than either sibling, which is exactly why its labelled doses read so much smaller than sildenafil's on the same page.
Parke-Davis / Warner-Lambert (historic)
2800 Plymouth Road, Ann Arbor, MI 48105, USA
Gabapentin was drawn up at Parke-Davis as a GABA look-alike meant to calm over-firing neurons. It never engaged the GABA receptor as designed; it quietened calcium channels instead, and found a durable second life in nerve pain and epilepsy. Warner-Lambert, and later Pfizer, brought Neurontin to market from this Michigan base.
Schering Corporation / Upjohn (Deltasone)
Kenilworth, New Jersey, USA
Prednisone was created in the mid-1950s by chemically tweaking cortisone so it fought inflammation harder while holding less salt and water. Schering's laboratories did the synthesis; the Deltasone brand was later marketed by Upjohn. Seventy years on it is still one of the most widely used oral steroids in medicine.
Laboratoires Aron / Jean Sterne, Paris
Suresnes, Île-de-France, France
Metformin's modern career began in 1950s Paris, where the physician Jean Sterne studied a compound drawn from goat's-rue and named the result Glucophage — 'glucose eater'. Long overlooked, it is now the first-line tablet for type 2 diabetes worldwide, and the trial data behind that status is among the strongest in the field.
U.S. Food and Drug Administration
10903 New Hampshire Avenue, Silver Spring, MD 20993, USA
The American regulator whose approved prescribing information fixes the doses, boxed warnings and interaction rules we quote. Where a page here and the current FDA label diverge, the label is the authority — the nitrate contraindication for the PDE5 tablets above all.
European Medicines Agency
Domenico Scarlattilaan 6, 1083 HS Amsterdam, Netherlands
The EU regulator whose scientific assessments and product information sit beside the FDA label in our reading. Its reviews are particularly useful on the reasoning behind each approved European indication and on class-wide safety updates.
Why the map still matters on a shelf
Sildenafil's start as a failed angina candidate is why a heart history still sits on every 25 mg note. Tadalafil's slow clearance out of Bothell is why a 10 mg weekend tablet and a 5 mg daily pack are different locks. Vardenafil's tightness at Wuppertal is why 20 mg is a ceiling, not a casual start. Gabapentin missed the GABA receptor and found calcium channels. Prednisone was a 1950s redesign of cortisone to fight inflammation with less salt hold. Metformin sat in a Paris drawer for years and is now the first tablet many type 2 patients meet. Each full note links back to the institution that shaped the molecule.