There are types of dysfluencies that are normal developmental processes and others that are more abnormal and atypical. Stuttering
Stuttering is the most common dysfluency disorder. it is an interruption in the flow of speaking characterized by repetitions, sound prolongations, and blocks that change the rhythm of sleep. A disturbance in the normal fluency and time patterning of speech that is inappropriate for the age of the person. Stuttering typically has its origins in childhood. Most who stutter will begin to do so around 2.5 years of age. Approximately 95% of children who stutter will start to do so before the age of 5. Stuttering symptoms may include dysfluencies such as hesitations, word fillers, nonword fillers, silent pauses, and interjections. All very similar to developmental dysfluency symptoms. Less typical stuttering will include sound/syllable repetitions, prolongations, and blocks. Stuttering can also occur with other speech and sound disorders, and intellectual language disabilities. Stuttering can greatly interfere with school, work or social interactions. Children who stutter may also experience fear or anxiety about social settings or public speaking. Speech patterns and behaviors that might signal that a child is potentially going to develop a stuttering disorder can include within-word or part0word repetitions prolonged sounds, avoiding speaking situations, looking frustrated or upset and tense appearance in neck muscles.If stuttering is familial there is likely a genetic mutation that causes the disorder. Unlike the aforementioned typical dysfluencies, stuttering can be a result of genetics.
Allopurinol was marketed at the time by Burroughs Wellcome. Allopurinol is a generic drug sold under a variety of brand names, including Allohexal, Allosig, Milurit, Alloril, Progout, Ürikoliz, Zyloprim, Zyloric, Zyrik, and Aluron. See also
Lesinurad/allopurinol, a fixed-dose combination drug
Hydroxychavicol, potent xanthine oxidase inhibitor

References
Further reading
Dean L (March 2016). "Allopurinol Therapy and HLA-B*58:01 Genotype". In Pratt VM, McLeod HL, Rubinstein WS,  et al. (eds.). Medical Genetics Summaries. National Center for Biotechnology Information (NCBI). PMID 28520356. External links
"Allopurinol". Drug Information Portal. U.S. National Library of Medicine. "PRODUCT INFORMATION Allopurinol Tablets USP". U.S. National Library of Medicine. Medication handout sheet (Revised: 07/2019 0603–2115)
Allopurinol pathway on PharmGKB