The service was the first of its kind in the UK. This evaluation provides evidence to inform the potential roll-out of further online strategies to enhance community HIV testing.

Ritonavir and cobicistat, used as pharmacokinetic enhancers in combination with some antiretrovirals (ARVs) for the treatment of HIV, are potent inhibitors of the CYP3A4 isoenzyme. Most glucocorticoids are metabolised via the CYP3A4 pathway and iatrogenic Cushing's syndrome (ICS), with possible secondary adrenal insufficiency (SAI), is a recognised complication following co-administration with ritonavir or cobicistat. A structured approach for identifying and managing potentially affected individuals has not been established. We systematically identified patients with ICS/SAI and found substantial heterogeneity in clinical practice across three large London HIV centres. While this significant drug interaction and its complications are now well-recognised, it is apparent that there is no standardised approach to management or guidance for the general physician. Here we describe the management of ICS/SAI in our current practice, review the available evidence and suggest practice recommendations. KEYWORDS : Adrenal insuffi ciency , cobicistat , Cushing's syndrome , HIV , ritonavir IntroductionRitonavir and cobicistat are pharmacokinetic enhancers used in the treatment of HIV infection. They are extremely potent inhibitors of cytochrome P450 3A4 (CYP3A4) activity. Ritonavir, originally developed as an antiretroviral, is used ABSTRACT Iatrogenic Cushing's syndrome due to drug interaction between glucocorticoids and the ritonavir or cobicistat containing HIV therapies at sub-therapeutic doses, in combination with HIV protease inhibitors (PIs), to significantly increase their concentrations and allow less frequent and lower dosing.1 Cobicistat was developed more recently and is similar in structure. It is used in combination with PIs or elvitegravir (an integrase inhibitor) 2 but has no antiretroviral activity itself. 3 The downside of this pharmacokinetic manipulation is the significant potential for interactions with CYP3A4 substrates, leading to side effects. CYP3A4 is the dominant isoenzyme of the hepatic cytochrome P450 system and is the primary metabolic step for the degradation of endogenous and most prescribed corticosteroids. The metabolism of these can therefore be decreased by inhibitors such as ritonavir/cobicistat. 4 Subsequent increases in exogenous corticosteroid plasma concentrations and half-life can lead to iatrogenic Cushing's syndrome (ICS) 5 and, at supraphysiological levels, to suppression of adrenocorticotropic hormone (ACTH) and endogenous corticosteroid secretion, potentially resulting in secondary adrenal insufficiency (SAI). There is abundant evidence highlighting this issue. 1,[6][7][8][9][10][11] However, a structured approach to identify and manage potentially affected individuals has not been established. We aim to summarise the current management of ICS/SAI in three large HIV patient cohorts, review the available literature and develop practice recommendations. Of note, cobicistat became available after the evaluation period covered; however, all advice for ritonavir is applicable to i...

DTG Cmax was significantly higher in older PLWH. Our data provides clinicians with key information on the safety of prescribing DTG in older PLWH.

All three InSTIs have impressive data on efficacy, tolerability and safety. The unique differences of each InSTI's pharmacokinetics and pharmacodynamics lend themselves to various clinical scenarios, enabling us as clinicians to provide better patient-centred care.

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Our data show marked differences in the elimination rates of dolutegravir and elvitegravir following treatment interruption, which is likely to impact the extent to which drug doses can be delayed or missed. They suggest that clinical differences may emerge in patients who have suboptimal adherence.

These data strongly support the use of formal screening and drug service referral pathways at the time of admission to hospital to engage HIV-positive drug users.

Objectives Dolutegravir has replaced efavirenz as first-line treatment in universal HIV guidelines. We sought to ascertain the contributory effect of SNPs in four key genes linked to dolutegravir disposition (UGT1A1, ABCG2, CYP3A and NR1I2) on plasma dolutegravir pharmacokinetics. Methods Paired pharmacogenetic/pharmacokinetic data from 93 subjects were analysed for association using multivariate linear regression. Results Co-occurring UGT1*28 and NR1I2 c.63396C>T homozygosity was associated with a 79% increase in AUC0–24 (P = 0.001; 27% if analysed individually), whilst combined ABCG2 c.421C>A and NR1I2 c.63396C>T variants were associated with a 43% increase in Cmax (P = 0.002) and a 39% increase in AUC0–24 (P = 0.002). When analysed individually, homozygosity for the NR1I2 c.63396C>T variant alleles was associated with a 28% increase in Cmax (P = 0.033) and homozygosity for the ABCG2 c.421C>A variant alleles was associated with a 28% increase in Cmax (P = 0.047). The UGT1A1*28 (rs8175347) poor metabolizer status (*28/*28; *28/*37; *37/*37) was individually associated with a 27% increase in AUC0–24 (P = 0.020). The combination of UGT1A1*28 poor metabolizer and UGT1A1*6 intermediate metabolizer statuses correlated with a 43% increase in AUC0–24 (P = 0.023). Conclusions This study showed a pharmacogenetic association between dolutegravir pharmacokinetics and variants in the ABCG2, UGT1A1 and NR1I2 genes, particularly when combined. Further research is warranted to confirm these associations in population-specific studies and to investigate their putative relationship with dolutegravir pharmacodynamics.