In March 2018, European Medicines Agency issued a warning on a possible risk of neuropsychiatric disorders (such as depression, anxiety and mood changes) following the use of oral retinoids, including isotretinoin, though the limitations of the available data did not allow them to clearly establish whether this risk was due to the use of retinoids.In 2012, a systematic review covering all articles in the literature related to isotretinoin, depression and suicide, as well as articles related to class effect, dose response, and biologic plausibility found that the literature reviewed was consistent with an association of isotretinoin administration and depression and with suicide in a subgroup of vulnerable individuals. Following this systematic review, in a 2014 review a group of Australian dermatologists and psychiatrists collaborated on a set of recommendations for safe prescribing of isotretinoin. However, whether isotretinoin use is causally associated with mental illness remains controversial.Evidence for depression being causally associated with isotretinoin use includes 41 reports of positive challenge/dechallenge/rechallenge with isotretinoin, involving administering isotretinoin, withdrawing the drug, and then re-administering it. The majority of these cases had no psychiatric history. There is also a temporal relationship between the development of depression and initiation of isotretinoin treatment, with most cases developing after 1–2 months of treatment. Further, higher doses of isotretinoin increase the risk of developing depression, with 25% of people showing depression on a dose of 3 mg/kg/day as compared with 3–4% at normal doses. Studies have uncovered several biological processes which may credibly explain the affective changes induced by isotretinoin.
A left posterior fascicular block (LPFB), also known as left posterior hemiblock (LPH), is a condition where the left posterior fascicle, which travels to the inferior and posterior portion of the left ventricle, does not conduct the electrical impulses from the atrioventricular node. The wave-front instead moves more quickly through the left anterior fascicle and right bundle branch, leading to a right axis deviation seen on the ECG. Definition
The American Heart Association has defined a LPFB as:
Frontal plane axis between 90° and 180° in adults
rS pattern in leads I and aVL
qR pattern in leads III and aVF
QRS duration less than 120 msThe broad nature of the posterior bundle as well as its dual blood supply makes isolated LPFB rare. See also
Left bundle branch block
Left anterior fascicular block

References
Further reading
Ma FS, Ma J, Tang K,  et al. (March 2006). "Left posterior fascicular block: a new endpoint of ablation for verapamil-sensitive idiopathic ventricular tachycardia". Chin. Med. J. 119 (5): 367–72. doi:10.1097/00029330-200603010-00003. PMID 16542578. == External links ==