Proteins, nucleic acids are best example of natural polymers. Similarly cellulose is also a natural polymer which acts as main structural component of plants. Usually natural polymers are composed by condensation polymerisation with the elimination of water molecule.
Drug-Laboratory Test Interactions. False-positive urine immunoassay screening tests for phencyclidine (PCP) and amphetamine have been reported in patients taking venlafaxine. This is due to lack of specificity of the screening tests. False positive test results may be expected for several days following discontinuation of venlafaxine therapy. Confirmatory tests, such as GC/MS will clear that misconception up asap...or if you are not using pcp and your dr is sceptical.
In brief: Not Likely. It is unlikely that Neurontin (Gabapentin) will trigger a false positive urine test for drugs. However, if you are taking other medications then these medication may alone or in combination with Neurontin trigger a positive urine screen. Also, poppy seeds and other foods, fermented or otherwise may result in positive screen.