Around 163 essential medicines are now unavailable from pharmacies in Greece, sector leaders have said, ahead of the nation's pharmacists' planned one-day strike on May 23.

The debt borne by pharmacies resulting from the failure of health insurers to reimburse them regularly for prescription drugs covered by the national organisation for healthcare provision, the EOPYY, is set to reach 1 billion euros by the end of this month. Of this total, 250 million euros relates to medicines supplied last year, while the debt for drugs supplied in March, April and May this year accounts for 750 million euros, according to pharmacy leaders quoted by IHS Global Insight.

As a result of these levels of debt, some pharmacies are refusing to supply reimbursed medicines unless patients pay for them upfront, and this is worsening the problem, say the reports, although they also note that patients who do pay for their drugs in this way are then being reimbursed by the EOPYY.

Further exacerbating the shortage problems are the very low drug prices in Greece, which are leading to parallel exporting of some products and suppliers deciding that for others the prices they can charge do not make their presence on the Greek market financially viable.

Another massive problem is that Greece has failed to contain its public spending on medicines within the 2.88 billion euro annual level set recently by its "troika" of creditors - the European Union (EU), the European Central Bank and the European Monetary Fund.  The system is exceeding the monthly limits set for it by around 50 million euros a month, making a total forecast overspend for the year of 600 million euros.

The country’s new electronic prescription system, designed to reduce waste and oversupply of medicines, was expected to be a major factor in controlling national drug spending. However, the system has had to be taken offline several times this month because of technical problems, and in April it was blocked when hackers uploaded around 1.5 million fake prescriptions, reports the Kathimineri news service.

So far, around 38,000 doctors and 10,800 pharmacies have been using the e-prescription system, recording a daily average of 140,000 prescriptions for drugs worth approximately 6.6 million euros, Kathimineri adds.

Meantime, multinational drugmakers are "prepared to take a reasonable approach" to continuing to supply Greece with medicines if the country does leave the eurozone, according to Richard Bergstrom, director general of the European Federation of Pharmaceutical Industries and Associations (EFPIA).

"There is no concrete plan but there is an understanding that, if something happened, we would need to move swiftly," Dow Jones Newswires reports Mr Bergstrom as saying.

"There are historic precedents where the pharmaceuticals industry has behaved very rationally and responsibly together with governments," he added, pointing for example to Argentina's financial collapse in 2002, when a number of drugmakers continued supplying the nation with their products, without payment, for a while.