Rates, determinants and success of implementing deprescribing in people with type 2 diabetes: A scoping review

BACKGROUND

Individualizing goals for people with type 2 diabetes may result in deintensification of medication, but a comprehensive picture of deprescribing practices is lacking.

AIMS

To conduct a scoping review in order to assess the rates, determinants and success of implementing deprescribing of glucose-, blood pressure- or lipid-lowering medications in people with diabetes.

METHODS

A systematic search on MEDLINE and Embase between January 2007 and January 2019 was carried out for deprescribing studies among people with diabetes. Outcomes were rates of deprescribing related to participant characteristics, the determinants and success of deprescribing, and its implementation. Critical appraisal was conducted using predefined tools.

RESULTS

Fourteen studies were included; eight reported on rates, nine on determinants and six on success and implementation. Bias was high for studies on success of deprescribing. Deprescribing rates ranged from 14% to 27% in older people with low HbA_1c levels, and from 16% to 19% in older people with low systolic blood pressure. Rates were not much affected by age, gender, frailty or life expectancy. Rates were higher when a reminder system was used to identify people with hypoglycaemia, which led to less overtreatment and fewer hypoglycaemic events. Most healthcare professionals accepted the concept of deprescribing but differed on when to conduct it. Deprescribing glucose-lowering medications could be successfully conducted in 62% to 75% of participants with small rises in HbA_1c .

CONCLUSIONS

Deprescribing of glucose-lowering medications seems feasible and acceptable, but was not widely implemented in the covered period. Support systems may enhance deprescribing. More studies on deprescribing blood pressure- and lipid-lowering medications in people with diabetes are needed.

The prevalence of co-prescription of clinically relevant CYP enzyme inhibitor and substrate drugs in community-dwelling elderly Australians

WHAT IS KNOWN AND OBJECTIVE

The elderly are at increased risk of adverse effects resulting from drug interactions due to decreased drug clearance and polypharmacy. This study examines the prevalence of the co-administration of clinically relevant cytochrome P450 (CYP) enzyme inhibitors with drugs that are substrates for these enzymes, in the community-dwelling elderly in Australia.

METHODS

Participants aged 75 years or older (n = 1045) were recruited via their general practitioners at four Australian sites (Newcastle, Sydney, Melbourne and Adelaide). A research nurse visited the home of each patient to compile a list of all prescription medications (including doses) currently used by the patient, and to complete assessments for depression, quality of life and cognitive status. The medication data were searched for the co-prescription of clinically relevant CYP inhibitor and corresponding substrate drugs.

RESULTS AND DISCUSSION

Potentially inappropriate CYP inhibitor-substrate combinations were found in 6·2% (65/1045) of patients. These patients were on significantly more medications (6·1 ± 3·0 vs. 3·9 ± 2·5; P = 0·001) and had a significantly lower physical quality of life (P = 0·047) than those who were not on any CYP inhibitor-substrate combinations. The most commonly prescribed inhibitor-substrate combinations involved the CYP 3A4 inhibitors, diltiazem and verapamil, with the substrates simvastatin or atorvastatin. Only 1 of 41 patients on a CYP3A4 inhibitor and a statin was prescribed a non-CYP 3A4 metabolized statin. Metoprolol was another substrate commonly co-prescribed with a CYP2D6 inhibitor. In many cases, the risks and benefits of potential interactions may have been considered by the GP as the prescribed doses of both the inhibitor and substrate were relatively low. There were, however, some notable exceptions, also involving the substrates simvastatin, atorvastatin and metoprolol. There were no GP factors that were associated with co-prescription of CYP inhibitors and substrates.

WHAT IS NEW AND CONCLUSION

There is not a particular GP demographic that should be targeted for education regarding CYP interactions, but a focus on particular medications such as the statins may reduce the potential for clinically significant drug-drug interactions. As CYP drug-drug interactions are more common in patients on higher number of medications, particular vigilance is required at the time of prescribing and dispensing medications for elderly patients with multiple conditions.

Role of mitochondria in contraction and pacemaking in the mouse uterus

BACKGROUND AND PURPOSE

Uterine spontaneous contraction and pacemaking are poorly understood. This study investigates the role of the mitochondrial Ca(2+) store in uterine activity.

EXPERIMENTAL APPROACH

We investigated the effects of mitochondrial and sarco-endoplasmic reticulum (SER) inhibitors on contraction, membrane potential (Vm) and cytosolic Ca(2+) concentration ([Ca(2+) ](c) ) in longitudinal smooth muscle of the mouse uterus.

KEY RESULTS

The mitochondrial agents rotenone, carbonylcyanide-3-chlorophenylhydrazone (CCCP), 7-chloro-5-(2-chlorophenyl)-1,5-dihydro-4,1-benzothiazepin-2(3H)-one (CGP37157) and kaempferol decreased the force of contractions. The ATP synthase inhibitor oligomycin had no significant effect. The effects of these agents were compared with those of SER inhibitors cyclopiazonic acid (CPA), 2-amino ethoxyphenylborate (2-APB) and caffeine. All agents, except CPA and oligomycin, decreased contractile force. CPA and CCCP transiently increased contraction frequency, which returned to control levels, whereas rotenone, CGP37157, kaempferol and 2-APB decreased frequency and caffeine had no significant effect. Application of the mitochondrial agents when CPA functionally inhibited stores did not change contraction frequency but, with the exception of kaempferol, decreased force. CCCP caused depolarization and maintained increase in [Ca(2+) ](c) or depolarization/transient hyperpolarization and transient increase in [Ca(2+) ](c) for oestrus and di-oestrus tissues respectively. Rotenone caused hyperpolarization and maintained increase in [Ca(2+) ](c) . CGP37157 and kaempferol caused hyperpolarization but no measurable change in [Ca(2+) ](c) . Application of a range of K(+) channel blockers indicated a role of Ca(2+) -activated K(+) (K(Ca) ) channels in the CCCP- and CGP37157-induced actions.

CONCLUSIONS AND IMPLICATIONS

Mitochondria have a modulatory role on uterine contractions, with mitochondrial inhibition reducing contraction amplitude and pacemaker frequency by changes in Vm, [Ca(2+) ](c) and/or Ca(2+) influx.

Demonstration of 5-HT3 receptor function and expression in the mouse bladder

The aim of this study was to demonstrate the presence of 5-HT(3) receptors in the mouse bladder and to determine their location. Bladder strips from female mice were set up in gassed Krebs-Henseleit solution at 37 degrees C and contractions recorded in response to electrical field stimulation (8 Hz, 60 V, 0.5-ms pulse duration) applied for 2 s every 50 s. The potentiating effects of 5-hydroxytryptamine (5-HT) were recorded (in the presence of 1-microM methysergide and 1-microM GR125487 to isolate the 5-HT(3) receptor response), and contractions were expressed as a percentage of the response to 0.1-M KCl. Responses to (5-HT) were also obtained in the presence of the 5-HT(3) receptor antagonist, ondansetron. RT-PCR was used to detect the expression of the 5-HT(3A) and 5-HT(3B) subunit transcripts of the mouse 5-HT(3) receptor. 5-HT and 5-HT(3) receptor agonists caused concentration-dependent increases in the force of neurogenic contractions without affecting the baseline tone. The rank order of potency was: meta-chloro-phenylbiguanide (m-CPB) = 5-HT > 2-methyl-5-HT (2m5-HT) = 1-phenylbiguanide (1-PBG). The respective pEC(50) values were: 6.42 +/- 0.2 = 5.95 +/- 0.19 > 5.35 +/- 0.12 = 5.14 +/- 0.13. m-CPB acted as a full agonist (E (max) = 40.65 +/- 3.81% KCl), but both 2m5-HT and 1-PBG acted as lower potency partial agonists. Ondansetron (30, 100, 300 nM) caused concentration-related rightward displacements to the concentration-effect curve to 5-HT. Nonlinear regression analysis of the effect of the ondansetron concentrations on the pEC(50) values produced a pK(B) value of 8.29 +/- 0.22. Desensitization of sensory nerves to the contractile effect of capsaicin (10 microM for 60 min) did not alter the ability of 5-HT to potentiate neurogenic contractions. 5-HT (3 microM) inhibited contractions induced by direct muscle stimulation (lignocaine, 300 microM and 10-ms pulse width). m-CPB also caused the same effect with a pIC(50) of 6.62 +/- 0.10 and an E (max) of 48.03 +/- 2.25%. The concentration-response curve to m-CPB was shifted rightwards by ondansetron (1 microM) giving an apparent pK(B) value of 8.15 +/- 0.33. mRNA for both the 5-HT(3A) and 5-HT(3B) receptor subunits was detected in the detrusor as well as the mucosa with a greater relative expression of the 5-HT(3A) subunit in both layers. This study demonstrates that 5-HT mediates enhanced neurogenic contractions of the mouse bladder muscle by an action at 5-HT(3) receptors located prejunctionally on nonsensory nerve elements. Additionally, an inhibitory postjunctional population of the 5-HT(3) receptor was identified. The presence of the 5-HT(3) receptor was confirmed by the expression of both 5-HT(3A) and 5-HT(3B) receptor subunits of the 5-HT(3) receptor.

Tachykinin-induced contraction of the guinea-pig isolated oesophageal mucosa is mediated by NK(2) receptors

1. The tachykinin receptor present in the guinea-pig oesophageal mucosa that mediates contractile responses of the muscularis mucosae has been characterized, using functional in vitro experiments. 2. The NK(1) receptor-selective agonist, [Sar(9)(O(2))Met(11)]SP and the NK(3) receptor-selective agonists, [MePhe(7)]-NKB and senktide, produced no response at submicromolar concentrations. The NK(2) receptor-selective agonists, [Nle(10)]-NKA(4 - 10), and GR 64,349 produced concentration-dependent contractile effects with pD(2) values of 8.20+/-0.16 and 8.30+/-0.15, respectively. 3. The concentration-response curve to the non-selective agonist, NKA (pD(2)=8.13+/-0.04) was shifted significantly rightwards only by the NK(2) receptor-selective antagonist, GR 159,897 and was unaffected by the NK(1) receptor-selective antagonist, SR 140,333 and the NK(3) receptor-selective antagonist, SB 222,200. 4. The NK(2) receptor-selective antagonist, GR 159,897, exhibited an apparent competitive antagonism against the NK(2) receptor-selective agonist, GR 64,349 (apparent pK(B) value=9.29+/-0.16) and against the non-selective agonist, NKA (apparent pK(B) value=8.71+/-0.19). 5. The NK(2) receptor-selective antagonist, SR 48,968 exhibited a non-competitive antagonism against the NK(2) receptor-selective agonist, [Nle(10)]-NKA(4 - 10). The pK(B) value was 10.84+/-0.19.6. It is concluded that the guinea-pig isolated oesophageal mucosa is a useful preparation for studying the effects of NK(2) receptor-selective agonists and antagonists as the contractile responses to various tachykinins are mediated solely by NK(2) receptors.

Effects of tachykinin receptor agonists and antagonists on the guinea-pig isolated oesophagus

1. Vagal nerve stimulation of the guinea-pig isolated oesophagus produced a triphasic tetrodotoxin (TTX)-sensitive contractile response. The third phase, which was resistant to ganglion blocking drugs, was selectively abolished by capsaicin, suggesting the involvement of one or more neuropeptides released from afferent neurons. Receptors on cholinergic neurons were subsequently activated because the response was atropine sensitive. Contractile responses resulting from exogenous substance P were abolished by atropine and TTX and enhanced by physostigmine. These findings suggest that the third phase may be mediated by the action of a substance P-like neuropeptide released from sensory nerve endings that subsequently activated cholinergic neurons. 2. The tachykinin receptors in the body of the guinea-pig oesophagus were characterized by determining the relative agonist potencies of natural tachykinins as well as tachykinin receptor-selective analogues. Antagonist affinities were also determined. The results indicated the presence of both NK2 and NK3 receptors. In addition, the effects of a cocktail of peptidase inhibitors (captopril, thiorphan and amastatin) on responses to various tachykinins and synthetic analogues were determined. The results indicate that one or more peptidases are present in this preparation. 3. Experiments using various tachykinin receptor antagonists were performed to determine whether the activation of tachykinin receptors played a role in the mediation of the third phase of the response to vagal nerve stimulation. While this response was unaffected by NK1 and NK2 receptor-selective antagonists, it was only partially inhibited (23%) by the NK3 receptor antagonist SR 142801. Thus, in the guinea-pig oesophagus, it appears that NK3 receptors play only a minor role in mediating a contractile response when afferent neurons are excited by vagal nerve stimulation.

Tachykinins play a minor role in mediating the third phase of the contractile response to vagal nerve stimulation of the guinea-pig oesophagus

The aim of this study was to determine whether tachykinin receptors might be involved in the mediation of the atropine- and capsaicin-sensitive third phase of a triphasic contractile response to vagal nerve stimulation of the guinea-pig isolated oesophagus. The third phase was inhibited 23.3 +/- 1.7% (P< 0.001, n = 5) and 30. 8 +/- 9.0% (P< 0.05, n = 5) by the NK(3)receptor antagonist, SR 142 801 (0.1 and 1 microM respectively). SR 142 801 (0.1 and 1 microM) had no significant effect on the response to a submaximal concentration of acetylcholine (0.1 mM, n = 4). The third phase was not significantly affected by NK(1)or NK(2)receptor antagonists. Thus, in the guinea-pig oesophagus, it appears that while NK(1)and NK(2)receptors are not involved, NK(3)receptors play a minor role in mediating a contractile response when afferent neurones are excited by vagal nerve stimulation.

Tachykinin receptors in the guinea-pig isolated oesophagus: a complex system

1. The tachykinin receptors mediating contraction of isolated longitudinal strips of the guinea-pig oesophageal body were characterized with substance P (SP), neurokinin A (NKA) and neurokinin B (NKB) as well as the analogues, [Sar9,Met(O2)11]SP, [Nle10]NKA(4-10) and [MePhe7]NKB, selective for NK1, NK2 and NK3, receptors, respectively. Experiments were performed both in the absence and presence of a cocktail of peptidase inhibitors, captopril (1 microM), thiorphan (1 microM) and amastatin (20 microM), in order to determine whether membrane bound proteases are important in the metabolism of tachykinins in this preparation. 2. All agonists produced concentration-dependent contractile effects. The presence of the peptidase inhibitors shifted the concentration-response curves of SP, [Nle10]NKA(4-10) and [MePhe7]NKB significantly leftwards and the concentration-response curve of NKB was shifted significantly rightwards. However, the EC50 values were significantly different only for [Nle10]NKA(4-10) and NKB. 3. In the presence of the peptidase inhibitors, the EC50 values of the selective agonists, [MePhe7]NKB (0.6 nM) and [Nle10]NKA(4-10) (66 nM) indicated the presence of both tachykinin NK3 and NK2 receptors. [MePhe7]NKB produced less than 50% of the maximal response obtained with the other agonists. Since [Sar9,Met(O2)11]SP produced a small response in the nanomolar concentration range in about 30% of the preparations tested, it is possible that some NK1 receptors were also present. 4. Assuming competitive antagonism, the NK2-selective antagonist SR 48,968 (30 nM) gave apparent pKH values of 8.13 and 8.65 for [Nle10]NKA(4-10) in the absence and presence of peptidase inhibitors, respectively, supporting the presence of NK2 receptors. 5. The NK3-selective antagonist SR 142,801 (0.1 microM), suppressed responses to low (0.1-10 nM) concentrations of [MePhe7]NKB. These contractile responses to [MePhe7]NKB were also abolished by atropine (0.6 microM) suggesting that this response was mediated via cholinergic nerves. 6. It is concluded that the guinea-pig oesophagus is a complex system which has both NK2 and NK3 receptors and possibly some NK1 receptors as-well.

Simultaneous comparison of nicotinic receptor antagonists on three nicotinic acetylcholine receptors

The relative potencies of several nicotinic cholinoceptor antagonists in producing tetanic fade and reduction of striated muscle contraction were investigated in the isolated guinea-pig oesophagus as well as the guinea-pig and rat phrenic nerve-diaphragm preparations. Contractile smooth muscle responses to vagal stimulation, which involves ganglionic activation, were also measured simultaneously with striated muscle responses in the oesophagus. The relative potency for inhibiting the response of oesophageal smooth muscle to vagal stimulation (20 Hz) was trimetaphan > mecamylamine > hexamethonium > tubocurarine > pancuronium. For oesophageal striated muscle, production of tetanic fade at 100 Hz and reduction in peak tetanic tension at 20 or 100 Hz showed a similar relative potency; pancuronium > tubocurarine > mecamylamine > trimetaphan > hexamethonium and similar results were obtained in the guinea-pig diaphragm for the antagonists investigated (pancuronium, tubocurarine and mecamylamine). In the rat phrenic nerve-diaphragm preparation, production of tetanic fade at 50 Hz and reduction in twitch or tetanic tension all showed the relative potency; tubocurarine > pancuronium > mecamylamine > trimetaphan > hexamethonium. These findings indicate differences in the nicotinic cholinoceptor subtypes involved in vagal ganglionic responses and those in tetanic fade.

Vagal nerve stimulation of the guinea-pig oesophagus

Vagal nerve stimulation of the isolated guinea-pig oesophagus resulted in a triphasic contractile response which was abolished by tetrodotoxin. The mechanisms for each of the three responses were investigated. The first response was abolished by the neuromuscular blocking drug, tubocurarine, and was unaffected by atropine. The second response to vagal nerve stimulation was abolished by the ganglion blocking drug, hexamethonium, and by tubocurarine at a higher concentration than that required to block the first response. The second response was also abolished by atropine and was enhanced by physostigmine. It was concluded that this response was due to preganglionic stimulation of smooth muscle. omega-Conotoxin GVIA selectively inhibited the third response. This response was resistant to the neuromuscular and ganglion blocking drugs yet was abolished by atropine and was enhanced by physostigmine. This implicates the involvement of cholinergic neurones activated independently of nicotinic ganglionic receptors. The third response was also selectively abolished by capsaicin and enhanced by thiorphan. Contractile responses resulting from exogenous substance P were abolished by atropine and tetrodotoxin and enhanced by physostigmine. These findings suggest that the third response may be mediated by the action of a substance P-like neuropeptide released from sensory nerve endings which subsequently activate cholinergic neurones.

Effects of steroid hormones and immunosuppressant drugs on defences against uterine microbial contamination in the rat

This study used rats as a mammalian model to investigate the effects of steroid hormones and immunosuppressant drugs on uterine microflora. It was shown that prednisolone acetate predisposed to uterine contamination unlike oestradiol, ciclosporin and cyclophosphamide. It therefore appears that the leucocyte component of the immune system does not normally play a role in preventing bacterial colonization of the uterus and that prednisolone is producing its effect via some other mechanism, possibly an effect on cervical mucus.

Reduction of salbutamol-induced drinking by putative and proven antidepressants

Salbutamol-induced drinking was determined in rats after 4 days of twice daily treatment with the conventional and putative antidepressants desipramine, clenbuterol or salbutamol. Drinking was also determined 21 h after a single dose of the abovementioned drugs. Both chronic and acute administration of the drugs resulted in a significant reduction in the salbutamol-induced fluid intake. The results suggest that these drugs decrease beta 2-adrenoceptor activity, but that repeated administration is not a prerequisite for the effect.