The purpose of this trial is to study the effect of Memantine (uncompetitive, moderate affinity, NMDA receptor antagonist that binds to the NMDA receptor channel, and regulates the calcium influx into the neurons), a drug used to treat Alzheimer´s disease, on the progression of Amyotrophic Lateral Sclerosis (ALS). Memantine is added to riluzole (the single drug approved to treat ALS).

Phase 2/3 trial in ALS patients Double-blinded, parallel, randomized (2 blocs, bulbar/spinal onset)

Memantine + riluzole x Placebo + Memantine

Inclusion criteria:

• < 75 years at disease onset
• < 3 years of disease progression
• ALS-FRS > 24
• FVC > 60
• Probable or definite disease (revised El Escorial criteria)
• No other medical condition
• Normal blood tests
• Regular medication on riluzole > 1 month
• Nerve conduction studies ruling out conduction block
• EMG with widespread loss of motor units (revised El Escorial criteria)
• At least one hand with ADM strength > 2 on MRC scale

Duration - 2 years

Evaluation - every 3 months

Primary outcome - ALS-FRS Secondary -SF36, Hamilton depression scale, motor unit number estimation, neurophysiological index, strength (clinical evaluation); side-effects

Intention to treat analysis

60 patients

number estimated for 50% change in decline rate of ALS-FRS

Inclusion Criteria:

• Definite or probable disease - revise El Escorial criteria
• Normal blood tests
• Riluzole treatment during 1 month or more
• EMG in accordance with El Escorial criteria

Exclusion Criteria:

• Other diseases (such as PNP)
• Both ADM muscles < 3 on MRC scale
• Conduction block on nerve conduction tests
• Disease duration > 3 years
• ALS-FRS < 25
• Forced vital capacity - <60%