Dr Claire Wiles made the emotional statement to the family of 86-year-old cancer survivor Eileen Cowles after the inquest heard Mrs Cowles had mistakenly been prescribed
two tablets a day instead of the correct dose of two tablets a month.
After giving evidence, a visibly upset Dr Wiles said: "I just want to say I'm sorry. I am sorry to the family."
Dr Wiles was newly qualified and had only been working as a GP at Park Row Medical Centre in Guiseley for just over a year when she made the mistake while transcribing a repeat prescription in November 2014.
The inquest heard Dr Wiles had also confirmed her prescription of 40,000 units per day of colecalciferol was correct after it was queried by both the care home where Mrs Cowles was being looked after and the pharmacy that dealt with the prescription.
The inquest heard the dosage given to Mrs Cowles would have instead been appropriate for a patient who had chronic liver disease.
The repeat prescription was issued by the Park Row Medical Centre in November 2014 and was repeated every month with the taken two capsules daily instruction up to and including February 2015.
The increased dose over a number of months led to Mrs Cowles suffering a condition called hypercalcimia, where there is too much Vitamin D in the blood.
She died after suffering intestinal bleeding caused by the high levels of calcium found in her blood as a consequence of the over prescription.
Mrs Cowles had been taking the drug improve bone strength after she fractured her left hip following a fall at home in September 2014.
Her family only discovered the fatal mistake after finding papers while clearing out her room at Primrose Court Ccare home in Guiseley after her death.
Dr Wiles said she had used The British National Formulary - a United Kingdom pharmaceutical reference book - to decide on the dosage applicable to the patient.
But Dr Wiles incorrectly prescribed 40,000 units a day of the tablet to Mrs Cowles - the appropriate dosage for a patient suffering from "chronic liver disease", the inquest heard.
She had not seen a hospital discharge advice note prior to signing the prescription and agreed that was an "error."
A repeat prescription enquiry was made on November 26, 2014, by Primrose Court care home home staff as they were confused by the lack of dosage given on the prescription from the GP, the inquest heard.
A note returned from the practice said ‘20,000 capsules take two’ - but no indication was given as to whether that was daily, weekly or monthly.
Her "high" dosage levels were then questioned by pharmacists at Boots at Colton - but they were again told by Dr Wiles to give Mrs Cowles two tablets per day instead of per month.
Several further repeat prescriptions were made and again care home staff were told to administer two 20,000 capsules daily.
Dr Wiles said when she looked at the BNF manual, she had "taken it to confirm" the dosage she had prescribed.
Dr Wiles agreed she had misread the page and prescribed the wrong dosage for someone who would have had "chronic liver disease".
The GP was also criticised in a report commissioned by West Yorkshire Police, which was read to the inquest
Expert witness Neil Lloyd-Jones wrote in the report: "Dr Wiles incorrectly stated the dosage to be daily rather than monthly.
"The fact Dr Wiles wrote out an incorrect prescription and failed to put in place a strategic management plan, in my opinion, the standard medical care would fall below the common acceptable medical ractice."
Mrs Cowles had a history of vascular dementia and had previously undergone extensive facial surgery to remove a tumour after suffering from cancer in 1996.
The inquest heard in 2014 Mrs Cowles suffered a fall at home, broke her hip and underwent surgery at Leeds General Infirmary.
She was prescribed two Vitamin D tablets per month before leaving hospital in a bid to strengthen her bones and prevent further fractures.
The inquest heard Mrs Cowles had to move into residential care and in October 2014 was being looked after at Primrose Court care home in Guiseley.
She also changed doctors and her new GP surgery was the Park Road Medical Centre at Guiseley..
GP Ibrahim Syed of Park Road Medical Centre at Guiseley previously told the inquest the dosage was a "mistake" and he would have scrutinised the repeat prescription in more detail if he wasn't pressed for time.
He said: "I think ultimately I had not spotted the fact the prescription was erroneous. Regretfully I had not picked up on the fact this was not a maintenance dose.
"I think it's human error, it's a case of having to scan a large number of prescriptions everyday compounded by trust I put in my colleagues.
"I think when you are less pressed for time it might be I would have been able to spot the erroneous dose. It was almost like a needle in a haystack.
"Regardless of whether you are busy or not, I put a lot of faith in my colleagues when they are setting up repeat prescriptions and it was further exacerbated by the workload at the time."
Former Home Office pathologist Dr Richard Shepherd said he had not encountered hypercalcimia as a cause of death in this way in is 35-year career.
Dr Shepherd said he could not rule out that the intestinal bleeding was spontaneous, but added: "I think it's much more likely than not that it was due to the hypercalcimia or a side effect."
Dr Shepherd said he coud not find any reason for a natural death.