The 38-year-old, who was married to the model for less than a year, was prescribed medication by his doctor after being injured in a fight.
Alex claims that he mistook took 11-year-old Harvey’s medication, which help him manage his Prader-Wills syndrome, for his own.
Explaining that his growth hormones were next to Harvey’s in the fridge, the father-of-one said:
‘It was an error on my part that I didn't check the label properly.
‘I never expected Kate to place Harvey's meds next to mine. On the face of it, they both looked identical.’
However a source told a UK magazine that this was the final strike for 35-year-old Katie in their already-dwindling marriage.
‘She told me, “this was the moment I lost all respect for him”,’ the friend revealed.
Human growth hormones are usually prescribed to help heal cartilage, muscle and bone, but are often used by body builders to build muscle.
A spokeswoman for mother-of-four Katie Price told a UK newspaper:
‘Katie and her family have been dealing with Harvey’s illnesses his whole life. They don’t allow a situation to exist where his medicine could be contaminated by or confused with any drugs belonging to any third party.’