The relationship of pain intensity and opioid craving with delayed methadone dose: A preliminary study of individuals with opioid use disorder

AIMS

Despite a strong theoretical link between opioid craving and pain, little is known about the temporal relationship between pain and craving and the acute experience of pain in the context of methadone treatment. Using a cross-over design, the current study evaluated the time course of pain and craving and objective experience of pain as a function of the last methadone dose.

METHODS

Participants (n = 20) presented for the study in the morning and either received methadone dose as scheduled or delayed dose until the afternoon. During the 4-h study visit, participants completed a series of tasks, including repeated assessment of pain and craving at 0, +40, +70, +130, +160 and +240 min and a cold pressor test (CPT) at +15 and +220 min.

RESULTS

Separate mixed model results demonstrated no effect of dosing condition on craving; however, there was a significant dosing condition by time interaction (F(5,209) = 3.38, P = .006) such that pain increased over time in the delayed methadone condition but decreased in time in the scheduled methadone condition. A mixed model predicting self-reported pain revealed a three-way interaction between dosing condition, craving and time (F(5,197) = 2.39, P = .039) explained by a positive association between craving and pain at each time point (except 240 min) in delayed condition (P-range = .004-.0001). A separate mixed model on CPT data indicated a significant condition by time interaction such that pain threshold decreased in the delayed, but not scheduled, condition (F(1,57) = 4.01, P = .050).

CONCLUSIONS

These preliminary findings highlight the potential for increased risks after even a short delay in receiving a methadone dose.

Germline mutations in an intermediate chain dynein cause primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is a genetically heterogeneous, autosomal recessive disorder caused by abnormal ciliary ultrastructure and function, characterized clinically by oto-sino-pulmonary disease. Mutations in an intermediate chain dynein (DNAI1; IC78) have recently been described in PCD patients, with outer dynein arm (ODA) defects. The aims of the current study were to test for novel DNAI1 mutations in 13 PCD patients with ODA defects (from 7 unrelated families) and to assess genotype/phenotype correlations in patients and family members. A previously reported mutation (219+3insT) was detected in three PCD patients from two families. The opposite allele had the novel missense mutation G1874C (W568S) in both affected individuals from one family, and a nonsense mutation G1875A (W568X) in an affected individual from another family. The tryptophan at position 568 is a highly conserved residue in the WD-repeat region, and a mutation is predicted to lead to abnormal folding of the protein and loss of function. None of these mutations were found in 32 other PCD patients with miscellaneous ciliary defects. Mutations in DNAI1 are causative for PCD with ODA defects, and are likely the genetic origin of clinical disease in some PCD patients with ultrastructural defects in the ODA.