Friday 27 July 2018

Viagra blows the lungs out

With 20/20 hindsight you might think "That's the worst idea I ever heard in my life". But it's easy to be correct after the fact. I told you everything you need to know about Viagra last year: tl;dr any increased priapic tumescence in the Republic of Cork is entirely in the mind. The supposed mechanism by which Viagra works is through peripheral vasodilation: the blood vessels get fatter so the surrounding tissue gets chubby.

A few years ago someone in the Netherlands wondered if they could mobilise this mechanism to solve a pregnancy problem. In some cases, the development of the placenta - which is a co-operative effort by the mother and her foetus - is a bit wonky and the traffic across the placental barrier becomes insufficient as the demand for more food and more oxygen increases though the pregnancy. This results in premies and teenies both of which are starting life with significant handicaps. If we could increase the flow through the pipes that are in the insufficient placenta, then maybe that would compensate; resulting in retention of the foetus for a few more [every day extra has significant positive outcome] days or weeks and/or higher birth weight when arrival is finally triggered.

In 2015, they got ethical approval and started to recruit women who fit the desired demographic - pregnant with marginal placental development. There aren't that many in the normal course of events, so they scheduled the trial to run for 5 years until 2020. Well I'm sorry to report that the experiment has been abruptly shut down after a mid-term review:
Group
BadLung
GoodLung
RowTot
Viagra
17
76
93=18%
Placebo
3
87
90=3%
ColTot
20
163
183
The Chi.Sq. test on that contingency table gives χ2 = 10.5 p = 0.001. In that small sample, you're 6x more likely to have a baby with lung-damage if you had the Viagra pills than if you got the placebo.  Note also that of the 17 babies who were born with lung damage 11 died. Let the litigation begin!
Reports: BBC - ABC says similar trial in Australia has been paused - Gizmodo.

Given how little we know and how 1-dimensional that knowledge is and how complicated and interweaved natural system are, it is a wonder we have developed any drugs which are both safe and effective. 1-dimensional knowledge is a cornerstone of scientific research rather than an unfortunate deficit or side-effect. The double-blind randomised control trial is the gold-standard of objective science: we plod along checking a single variable at a time deliberately ignoring the interaction terms. In the case of Viagra, which inhibits an enzyme cGMP-specific phosphodiesterase type 5 PDE5, do we really have clue about the full range of functions that this enzyme has?

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