Drugs for chronic pain

1. Nitrooxyderivatives or salts thereof of formula (I)

R—NR 1c (K) k0 —(B) b0 —(C) c0 —NO 2   (I)

wherein

c0 is 1;

b0 is 0;

k0 is 1;

R 1c is H;

K is the bivalent radical (1C) of the formula:

R t and R′ t , same or different, are H, C 1 -C 10 -alkyl, phenyl or benzyl, —COOR y , in which R y =H, C 1 -C 10 -alkyl, phenyl, or benzyl;

C=bivalent radical of formula -T c -Y

wherein

T c =(CO);

Y is an alkylenoxy group —R′O— in which R′ is straight or branched C 1 -C 20 or a cycloalkylene with from 5 to 7 carbon atoms;

wherein n3 is an integer from 0 to 5 and n3′ is an integer from 1 to 3;

R is the radical of an analgesic drug of formula (II):

wherein:

W is a carbon atom;

m is 1;

R 0 =—(CH 2 ) n —COOR y , wherein R y =H, C 1 -C 10 -alkyl, phenyl, or benzyl;

n is an integer of from 0 to 2;

R 1 =H;

R 2 is:

a radical of formula (IIA), wherein optionally an ethylenic unsaturation may be present between the carbon atoms in position 1 and 2:

wherein:

p, p 1 , p 2 are 0;

p 3 is 0;

R 4 is hydrogen;

R 5 is hydrogen or a straight or branched C 1 -C 6 -alkyl,

Q is straight or branched C 1 -C 6 -alkyl; or

in formula (II) R 2 and R 1 with W together form a C 4 -C 10 saturated or unsaturated ring.

2. Compounds according to claim 1 , wherein:

in formula (II):

n=1, R y =H;

R 1 and R 2 with W form a cyclohexane ring; the drug precursor of R having the formula R—NH 2 is known as gabapentin; or

in formula (II):

n=1, R y =H,

R 1 =H

R 2 is the radical of formula (IIA) in which R 5 =Q=CH 3 ; the drug precursor of R having the formula R—NH 2 is known as (S)-3-isobutilGABA.

3. Compounds according to claim 1 selected from:

1-{[4-(nitrooxymethyl)benzoyloxy]methoxycarbonylaminomethyl}-cyclohexaneacetic acid (XXA),

1-{[3-(nitrooxymethyl)benzoyloxy]methoxycarbonylaminomethyl}-cyclohexaneacetic acid (XXIA),

1-{[2-(nitrooxymethyl)benzoyloxy]methoxycarbonylaminomethyl}-cyclohexaneacetic acid (XXIIA),

3(S)-{[2-(nitrooxymethyl)benzoyloxy]methoxycarbonylaminomethyl}-5-methyl-hexanoic acid (XXXA),

3(S)-{[3-(nitrooxymethyl)benzoyloxy]methoxycarbonylaminormethyl}-5-methyl-hexanoic acid (XXXIA),

3(S)-[4-(nitrooxymethyl)benzoyloxy]methoxycarbonylaminomethyl}-5-methyl-hexanoic acid (XXXIIA), and

4. A composition comprising: a compound according to claim 1 , and a NO-donor compound comprising a radical of a drug selected from the group consisting of: aspirin, salicylic acid, ibuprofen, paracetamol, naproxen, diclofenac and flurbiprofen and at least a group that is an —ONO 2 group or an —ONO group.

5. Pharmaceutical compositions comprising compounds according to claim 1 as active ingredients.

6. A method of treatment of chronic pain comprising administering an effective amount of the compounds according to claim 1 .

7. The method according to claim 6 , wherein the chronic pain is neurophatic pain.