UPDATE 1-Merck KGaA's profit bolstered by lab supplies, drug milestone payments

* Life Science unit boosted by demand for lab supplies and gear

* Milestone payments from partners bolster Healthcare unit

* Q2 group adj EBITDA up 23.8% at 1.14 bln eur

* Confirms FY profit guidance (Adds details on Life Science, Healthcare unit)

By Ludwig Burger

FRANKFURT, Aug 8 (Reuters) - Germany's Merck KGaA posted a gain in quarterly earnings that was slightly higher than market expectations thanks to strong sales growth at its lab supplies unit and milestone payments from drug development partners.

Second-quarter earnings before interest, taxes, depreciation and amortisation (EBITDA), adjusted for special items, gained 23.8% to 1.14 billion euros ($1.28 billion), Merck said on Thursday, slightly above the analyst estimate of 1.11 billion euros in a Refinitiv poll.

Merck's Life Science unit, which makes supplies and gear for the biotech industry, saw adjusted EBITDA gain 18 percent to 533 million euros, driven by demand for gene editing technology and water purification, among other processing tools.

The unit is benefiting from a race in the drug industry to develop new treatments.

Adjusted EBITDA at Merck's own pharmaceuticals business jumped 39% to 528 million euros, helped by agreed payments from partners Pfizer for achievements in developing cancer drug Bavencio and GlaxoSmithKline for advancing novel cancer immunotherapy bintrafusp alfa.

Merck confirmed its guidance for an underlying increase of 10-13% in 2019 EBITDA and adjusted for one-off items but now sees a positive effect of 0% to +2% from currencies.

($1 = 0.8921 euros) (Reporting by Ludwig Burger Editing by Michelle Martin)